Merge pull request #16 from eugenp/master

New Code

JGit/pom.xml

@@ -0,0 +1,63 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung</groupId>
+    <artifactId>JGitSnippets</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    <url>http://maven.apache.org</url>
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+    </properties>
+    <repositories>
+    <repository>
+      <id>jgit-repository</id>
+      <url>https://repo.eclipse.org/content/groups/releases/</url>
+    </repository>
+  </repositories>
+
+  <!-- Core Library -->
+  <dependencies>
+    <dependency>
+      <groupId>org.eclipse.jgit</groupId>
+      <artifactId>org.eclipse.jgit</artifactId>
+      <version>4.5.0.201609210915-r</version>
+    </dependency>
+    <dependency>
+      <groupId>org.eclipse.jgit</groupId>
+      <artifactId>org.eclipse.jgit.archive</artifactId>
+      <version>4.5.0.201609210915-r</version>
+    </dependency>
+	<dependency>
+		<groupId>commons-io</groupId>
+		<artifactId>commons-io</artifactId>
+		<version>2.5</version>
+	</dependency>
+	<dependency>
+		<groupId>org.slf4j</groupId>
+		<artifactId>slf4j-simple</artifactId>
+		<version>1.7.21</version>
+	</dependency>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.12</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.2</version>
+        <configuration>
+          <source>1.7</source>
+          <target>1.7</target>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+</project>

JGit/src/main/java/com/baeldung/jgit/CreateNewRepository.java

@@ -0,0 +1,30 @@
+package com.baeldung.jgit;
+
+import java.io.File;
+import java.io.IOException;
+import org.apache.commons.io.FileUtils;
+import org.eclipse.jgit.api.Git;
+import org.eclipse.jgit.api.errors.GitAPIException;
+
+/**
+ * Simple snippet which shows how to create a new repository
+ *
+ * 
+ */
+public class CreateNewRepository {
+
+    public static void main(String[] args) throws IOException, IllegalStateException, GitAPIException {
+        // prepare a new folder
+        File localPath = File.createTempFile("TestGitRepository", "");
+        if(!localPath.delete()) {
+            throw new IOException("Could not delete temporary file " + localPath);
+        }
+
+        // create the directory
+        try (Git git = Git.init().setDirectory(localPath).call()) {
+            System.out.println("Having repository: " + git.getRepository().getDirectory());
+        }
+
+        FileUtils.deleteDirectory(localPath);
+    }
+}

JGit/src/main/java/com/baeldung/jgit/OpenRepository.java

@@ -0,0 +1,65 @@
+package com.baeldung.jgit;
+
+import com.baeldung.jgit.helper.Helper;
+import org.eclipse.jgit.api.Git;
+import org.eclipse.jgit.api.errors.GitAPIException;
+import org.eclipse.jgit.lib.Ref;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.storage.file.FileRepositoryBuilder;
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * Simple snippet which shows how to open an existing repository
+ *
+ * 
+ */
+public class OpenRepository {
+
+    public static void main(String[] args) throws IOException, GitAPIException {
+        // first create a test-repository, the return is including the .get directory here!
+        File repoDir = createSampleGitRepo();
+
+        // now open the resulting repository with a FileRepositoryBuilder
+        FileRepositoryBuilder builder = new FileRepositoryBuilder();
+        try (Repository repository = builder.setGitDir(repoDir)
+                .readEnvironment() // scan environment GIT_* variables
+                .findGitDir() // scan up the file system tree
+                .build()) {
+            System.out.println("Having repository: " + repository.getDirectory());
+
+            // the Ref holds an ObjectId for any type of object (tree, commit, blob, tree)
+            Ref head = repository.exactRef("refs/heads/master");
+            System.out.println("Ref of refs/heads/master: " + head);
+        }
+    }
+
+    private static File createSampleGitRepo() throws IOException, GitAPIException {
+        try (Repository repository = Helper.createNewRepository()) {
+            System.out.println("Temporary repository at " + repository.getDirectory());
+
+            // create the file
+            File myfile = new File(repository.getDirectory().getParent(), "testfile");
+            if(!myfile.createNewFile()) {
+                throw new IOException("Could not create file " + myfile);
+            }
+
+            // run the add-call
+            try (Git git = new Git(repository)) {
+                git.add()
+                        .addFilepattern("testfile")
+                        .call();
+
+
+                // and then commit the changes
+                git.commit()
+                        .setMessage("Added testfile")
+                        .call();
+            }
+
+            System.out.println("Added file " + myfile + " to repository at " + repository.getDirectory());
+
+            return repository.getDirectory();
+        }
+    }
+}

JGit/src/main/java/com/baeldung/jgit/helper/Helper.java

@@ -0,0 +1,33 @@
+
+package com.baeldung.jgit.helper;
+
+import java.io.File;
+import java.io.IOException;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.storage.file.FileRepositoryBuilder;
+
+public class Helper {
+    
+    public static Repository openJGitRepository() throws IOException {
+        FileRepositoryBuilder builder = new FileRepositoryBuilder();
+        return builder
+                .readEnvironment() // scan environment GIT_* variables
+                .findGitDir() // scan up the file system tree
+                .build();
+    }
+    
+     public static Repository createNewRepository() throws IOException {
+        // prepare a new folder
+        File localPath = File.createTempFile("TestGitRepository", "");
+        if(!localPath.delete()) {
+            throw new IOException("Could not delete temporary file " + localPath);
+        }
+
+        // create the directory
+        Repository repository = FileRepositoryBuilder.create(new File(localPath, ".git"));
+        repository.create();
+
+        return repository;
+    }
+    
+}

JGit/src/main/java/com/baeldung/jgit/porcelain/AddFile.java

@@ -0,0 +1,36 @@
+package com.baeldung.jgit.porcelain;
+
+import java.io.File;
+import java.io.IOException;
+import com.baeldung.jgit.helper.Helper;
+import org.eclipse.jgit.api.Git;
+import org.eclipse.jgit.api.errors.GitAPIException;
+import org.eclipse.jgit.lib.Repository;
+
+/**
+ * Simple snippet which shows how to add a file to the index
+ *
+ * 
+ */
+public class AddFile {
+
+    public static void main(String[] args) throws IOException, GitAPIException {
+        // prepare a new test-repository
+        try (Repository repository = Helper.createNewRepository()) {
+            try (Git git = new Git(repository)) {
+                // create the file
+                File myfile = new File(repository.getDirectory().getParent(), "testfile");
+                if(!myfile.createNewFile()) {
+                    throw new IOException("Could not create file " + myfile);
+                }
+
+                // run the add-call
+                git.add()
+                        .addFilepattern("testfile")
+                        .call();
+
+                System.out.println("Added file " + myfile + " to repository at " + repository.getDirectory());
+            }
+        }
+    }
+}

JGit/src/main/java/com/baeldung/jgit/porcelain/CommitAll.java

@@ -0,0 +1,51 @@
+package com.baeldung.jgit.porcelain;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.PrintWriter;
+import com.baeldung.jgit.helper.Helper;
+import org.eclipse.jgit.api.Git;
+import org.eclipse.jgit.api.errors.GitAPIException;
+import org.eclipse.jgit.lib.Repository;
+
+/**
+ * Simple snippet which shows how to commit all files
+ *
+ * 
+ */
+public class CommitAll {
+
+    public static void main(String[] args) throws IOException, GitAPIException {
+        // prepare a new test-repository
+        try (Repository repository = Helper.createNewRepository()) {
+            try (Git git = new Git(repository)) {
+                // create the file
+                File myfile = new File(repository.getDirectory().getParent(), "testfile");
+                if(!myfile.createNewFile()) {
+                    throw new IOException("Could not create file " + myfile);
+                }
+
+                // Stage all files in the repo including new files
+                git.add().addFilepattern(".").call();
+
+                // and then commit the changes.
+                git.commit()
+                        .setMessage("Commit all changes including additions")
+                        .call();
+
+                try(PrintWriter writer = new PrintWriter(myfile)) {
+                    writer.append("Hello, world!");
+                }
+
+                // Stage all changed files, omitting new files, and commit with one command
+                git.commit()
+                        .setAll(true)
+                        .setMessage("Commit changes to all files")
+                        .call();
+
+
+                System.out.println("Committed all changes to repository at " + repository.getDirectory());
+            }
+        }
+    }
+}

JGit/src/main/java/com/baeldung/jgit/porcelain/CreateAndDeleteTag.java

@@ -0,0 +1,56 @@
+package com.baeldung.jgit.porcelain;
+
+import java.io.IOException;
+import com.baeldung.jgit.helper.Helper;
+import org.eclipse.jgit.api.Git;
+import org.eclipse.jgit.api.errors.GitAPIException;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.Ref;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.revwalk.RevWalk;
+
+/**
+ * Simple snippet which shows how to create a tag
+ *
+ * 
+ */
+public class CreateAndDeleteTag {
+
+    public static void main(String[] args) throws IOException, GitAPIException {
+        // prepare test-repository
+        try (Repository repository = Helper.openJGitRepository()) {
+            try (Git git = new Git(repository)) {
+                // remove the tag before creating it
+                git.tagDelete().setTags("tag_for_testing").call();
+
+                // set it on the current HEAD
+                Ref tag = git.tag().setName("tag_for_testing").call();
+                System.out.println("Created/moved tag " + tag + " to repository at " + repository.getDirectory());
+
+                // remove the tag again
+                git.tagDelete().setTags("tag_for_testing").call();
+
+                // read some other commit and set the tag on it
+                ObjectId id = repository.resolve("HEAD^");
+                try (RevWalk walk = new RevWalk(repository)) {
+                    RevCommit commit = walk.parseCommit(id);
+                    tag = git.tag().setObjectId(commit).setName("tag_for_testing").call();
+                    System.out.println("Created/moved tag " + tag + " to repository at " + repository.getDirectory());
+
+                    // remove the tag again
+                    git.tagDelete().setTags("tag_for_testing").call();
+
+                    // create an annotated tag
+                    tag = git.tag().setName("tag_for_testing").setAnnotated(true).call();
+                    System.out.println("Created/moved tag " + tag + " to repository at " + repository.getDirectory());
+
+                    // remove the tag again
+                    git.tagDelete().setTags("tag_for_testing").call();
+
+                    walk.dispose();
+                }
+            }
+        }
+    }
+}

JGit/src/main/java/com/baeldung/jgit/porcelain/Log.java

@@ -0,0 +1,74 @@
+package com.baeldung.jgit.porcelain;
+
+import java.io.IOException;
+import com.baeldung.jgit.helper.Helper;
+import org.eclipse.jgit.api.Git;
+import org.eclipse.jgit.api.errors.GitAPIException;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.revwalk.RevCommit;
+
+/**
+ * Simple snippet which shows how to get the commit-ids for a file to provide log information.
+ *
+ * 
+ */
+public class Log {
+
+    @SuppressWarnings("unused")
+    public static void main(String[] args) throws IOException, GitAPIException {
+        try (Repository repository = Helper.openJGitRepository()) {
+            try (Git git = new Git(repository)) {
+                Iterable<RevCommit> logs = git.log()
+                        .call();
+                int count = 0;
+                for (RevCommit rev : logs) {
+                    //System.out.println("Commit: " + rev /* + ", name: " + rev.getName() + ", id: " + rev.getId().getName() */);
+                    count++;
+                }
+                System.out.println("Had " + count + " commits overall on current branch");
+
+                logs = git.log()
+                        .add(repository.resolve("remotes/origin/testbranch"))
+                        .call();
+                count = 0;
+                for (RevCommit rev : logs) {
+                    System.out.println("Commit: " + rev /* + ", name: " + rev.getName() + ", id: " + rev.getId().getName() */);
+                    count++;
+                }
+                System.out.println("Had " + count + " commits overall on test-branch");
+
+                logs = git.log()
+                        .all()
+                        .call();
+                count = 0;
+                for (RevCommit rev : logs) {
+                    //System.out.println("Commit: " + rev /* + ", name: " + rev.getName() + ", id: " + rev.getId().getName() */);
+                    count++;
+                }
+                System.out.println("Had " + count + " commits overall in repository");
+
+                logs = git.log()
+                        // for all log.all()
+                        .addPath("README.md")
+                        .call();
+                count = 0;
+                for (RevCommit rev : logs) {
+                    //System.out.println("Commit: " + rev /* + ", name: " + rev.getName() + ", id: " + rev.getId().getName() */);
+                    count++;
+                }
+                System.out.println("Had " + count + " commits on README.md");
+
+                logs = git.log()
+                        // for all log.all()
+                        .addPath("pom.xml")
+                        .call();
+                count = 0;
+                for (RevCommit rev : logs) {
+                    //System.out.println("Commit: " + rev /* + ", name: " + rev.getName() + ", id: " + rev.getId().getName() */);
+                    count++;
+                }
+                System.out.println("Had " + count + " commits on pom.xml");
+            }
+        }
+    }
+}

JGit/src/test/java/com/baeldung/jgit/JGitBugTest.java

@@ -0,0 +1,31 @@
+import com.baeldung.jgit.helper.Helper;
+import org.eclipse.jgit.lib.ObjectLoader;
+import org.eclipse.jgit.lib.ObjectReader;
+import org.eclipse.jgit.lib.Ref;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.revwalk.RevWalk;
+import org.junit.Test;
+import java.io.IOException;
+import static org.junit.Assert.assertNotNull;
+
+/**
+ * Tests which show issues with JGit that we reported upstream.
+ */
+public class JGitBugTest {
+    @Test
+    public void testRevWalkDisposeClosesReader() throws IOException {
+        try (Repository repo = Helper.openJGitRepository()) {
+            try (ObjectReader reader = repo.newObjectReader()) {
+                try (RevWalk walk = new RevWalk(reader)) {
+                    walk.dispose();
+
+                    Ref head = repo.exactRef("refs/heads/master");
+                    System.out.println("Found head: " + head);
+
+                    ObjectLoader loader = reader.open(head.getObjectId());
+                    assertNotNull(loader);
+                }
+            }
+        }
+    }
+}

JGit/src/test/java/com/baeldung/jgit/porcelain/PorcelainTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.jgit.porcelain;
+
+import org.junit.Test;
+
+public class PorcelainTest {
+    @Test
+    public void runSamples() throws Exception {
+        // simply call all the samples to see any severe problems with the samples
+        AddFile.main(null);
+        
+        CommitAll.main(null);
+        
+        CreateAndDeleteTag.main(null);
+         
+        Log.main(null);    
+    }
+}

annotations/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <parent>
         <artifactId>parent-modules</artifactId>

apache-fop/pom.xml

@@ -1,4 +1,5 @@
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.baeldung</groupId>
     <artifactId>apache-fop</artifactId>

aspectj/README.md

@@ -1,2 +1,3 @@
 ### Relevant Articles:
 - [Intro to AspectJ](http://www.baeldung.com/aspectj)
+- [Spring Performance Logging](http://www.baeldung.com/spring-performance-logging)

aspectj/pom.xml

@@ -111,18 +111,8 @@
                     <Xlint>ignore</Xlint>
                     <encoding>${project.build.sourceEncoding}</encoding>
                     <!-- Post-compile weaving -->
-                    <!--
+                    <!-- <weaveDependencies> <weaveDependency> <groupId>org.agroup</groupId> <artifactId>to-weave</artifactId> </weaveDependency> 
-                    <weaveDependencies>
+                        <weaveDependency> <groupId>org.anothergroup</groupId> <artifactId>gen</artifactId> </weaveDependency> </weaveDependencies> -->
-                        <weaveDependency>
-                              <groupId>org.agroup</groupId>
-                              <artifactId>to-weave</artifactId>
-                        </weaveDependency>
-                        <weaveDependency>
-                              <groupId>org.anothergroup</groupId>
-                              <artifactId>gen</artifactId>
-                        </weaveDependency>
-                      </weaveDependencies>
-                      -->
                 </configuration>
                 <executions>
                     <execution>
@@ -134,18 +124,9 @@
                 </executions>
             </plugin>
 
-            <!-- 
+            <!-- <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <version>2.10</version> 
-            <plugin>
+                <configuration> <argLine>-javaagent:"${settings.localRepository}"/org/aspectj/aspectjweaver/${aspectj.version}/aspectjweaver-${aspectj.version}.jar</argLine> 
-                <groupId>org.apache.maven.plugins</groupId>
+                <useSystemClassLoader>true</useSystemClassLoader> <forkMode>always</forkMode> </configuration> </plugin> -->
-                <artifactId>maven-surefire-plugin</artifactId>
-                <version>2.10</version>
-                <configuration>
-                    <argLine>-javaagent:"${settings.localRepository}"/org/aspectj/aspectjweaver/${aspectj.version}/aspectjweaver-${aspectj.version}.jar</argLine>
-                    <useSystemClassLoader>true</useSystemClassLoader>
-                    <forkMode>always</forkMode>
-                </configuration>
-            </plugin>
-             -->
         </plugins>
     </build>
 

core-java-9/pom.xml

@@ -1,5 +1,4 @@
-<project xmlns="http://maven.apache.org/POM/4.0.0" 
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-		xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.baeldung</groupId>
@@ -23,8 +22,6 @@
             <version>${org.slf4j.version}</version>
         </dependency>
 
-
-
         <dependency>
             <groupId>org.hamcrest</groupId>
             <artifactId>hamcrest-library</artifactId>

core-java/.gitignore

@@ -16,3 +16,7 @@
 *.txt
 /bin/
 /temp
+
+#IntelliJ specific
+.idea
+*.iml

core-java/README.md

@@ -53,3 +53,4 @@
 - [Calculate the Size of a File in Java](http://www.baeldung.com/java-file-size)
 - [The Basics of Java Generics](http://www.baeldung.com/java-generics)
 - [The Traveling Salesman Problem in Java](http://www.baeldung.com/java-simulated-annealing-for-traveling-salesman)
+- [How to Create an Executable JAR with Maven](http://www.baeldung.com/executable-jar-with-maven)

core-java/pom.xml

@@ -63,6 +63,12 @@
             <artifactId>grep4j</artifactId>
             <version>${grep4j.version}</version>
         </dependency>
+        
+        <dependency>
+            <groupId>com.lmax</groupId>
+            <artifactId>disruptor</artifactId>
+            <version>${disruptor.version}</version>
+        </dependency>
         <!-- web -->
 
         <!-- marshalling -->
@@ -352,7 +358,7 @@
         <logback.version>1.1.7</logback.version>
 
         <!-- util -->
-        <guava.version>19.0</guava.version>
+        <guava.version>21.0</guava.version>
         <commons-lang3.version>3.5</commons-lang3.version>
         <bouncycastle.version>1.55</bouncycastle.version>
         <commons-codec.version>1.10</commons-codec.version>
@@ -363,6 +369,7 @@
         <unix4j.version>0.4</unix4j.version>
         <grep4j.version>1.8.7</grep4j.version>
         <lombok.version>1.16.12</lombok.version>
+        <disruptor.version>3.3.6</disruptor.version>
 
         <!-- testing -->
         <org.hamcrest.version>1.3</org.hamcrest.version>

core-java/src/main/java/com/baeldung/chainedexception/LogWithChain.java

@@ -0,0 +1,44 @@
+package com.baeldung.chainedexception;
+
+import com.baeldung.chainedexception.exceptions.GirlFriendOfManagerUpsetException;
+import com.baeldung.chainedexception.exceptions.ManagerUpsetException;
+import com.baeldung.chainedexception.exceptions.NoLeaveGrantedException;
+import com.baeldung.chainedexception.exceptions.TeamLeadUpsetException;
+
+public class LogWithChain {
+
+    public static void main(String[] args) throws Exception {
+        getLeave();
+    }
+
+    private static void getLeave() throws NoLeaveGrantedException {
+        try {
+            howIsTeamLead();
+        } catch (TeamLeadUpsetException e) {
+            throw new NoLeaveGrantedException("Leave not sanctioned.", e);
+        }
+    }
+
+    private static void howIsTeamLead() throws TeamLeadUpsetException {
+        try {
+            howIsManager();
+        } catch (ManagerUpsetException e) {
+            throw new TeamLeadUpsetException(
+                    "Team lead is not in good mood", e);
+        }
+    }
+
+    private static void howIsManager() throws ManagerUpsetException {
+        try {
+            howIsGirlFriendOfManager();
+        } catch (GirlFriendOfManagerUpsetException e) {
+            throw new ManagerUpsetException("Manager is in bad mood", e);
+        }
+    }
+
+    private static void howIsGirlFriendOfManager()
+            throws GirlFriendOfManagerUpsetException {
+        throw new GirlFriendOfManagerUpsetException(
+                "Girl friend of manager is in bad mood");
+    }
+}

core-java/src/main/java/com/baeldung/chainedexception/LogWithoutChain.java

@@ -0,0 +1,47 @@
+package com.baeldung.chainedexception;
+
+import com.baeldung.chainedexception.exceptions.GirlFriendOfManagerUpsetException;
+import com.baeldung.chainedexception.exceptions.ManagerUpsetException;
+import com.baeldung.chainedexception.exceptions.NoLeaveGrantedException;
+import com.baeldung.chainedexception.exceptions.TeamLeadUpsetException;
+
+public class LogWithoutChain {
+
+    public static void main(String[] args) throws Exception {
+        getLeave();
+    }
+
+    private static void getLeave() throws NoLeaveGrantedException {
+        try {
+            howIsTeamLead();
+        } catch (TeamLeadUpsetException e) {
+            e.printStackTrace();
+            throw new NoLeaveGrantedException("Leave not sanctioned.");
+        }
+    }
+
+    private static void howIsTeamLead() throws TeamLeadUpsetException {
+        try {
+            howIsManager();
+        } catch (ManagerUpsetException e) {
+            e.printStackTrace();
+            throw new TeamLeadUpsetException(
+                    "Team lead is not in good mood");
+        }
+    }
+
+    private static void howIsManager() throws ManagerUpsetException {
+        try {
+            howIsGirlFriendOfManager();
+        } catch (GirlFriendOfManagerUpsetException e) {
+            e.printStackTrace();
+            throw new ManagerUpsetException("Manager is in bad mood");
+        }
+    }
+
+    private static void howIsGirlFriendOfManager()
+            throws GirlFriendOfManagerUpsetException {
+        throw new GirlFriendOfManagerUpsetException(
+                "Girl friend of manager is in bad mood");
+    }
+}

core-java/src/main/java/com/baeldung/chainedexception/exceptions/GirlFriendOfManagerUpsetException.java

@@ -0,0 +1,12 @@
+package com.baeldung.chainedexception.exceptions;
+
+public class GirlFriendOfManagerUpsetException extends Exception {
+
+    public GirlFriendOfManagerUpsetException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public GirlFriendOfManagerUpsetException(String message) {
+        super(message);
+    }
+}

core-java/src/main/java/com/baeldung/chainedexception/exceptions/ManagerUpsetException.java

@@ -0,0 +1,12 @@
+package com.baeldung.chainedexception.exceptions;
+
+public class ManagerUpsetException extends Exception {
+
+    public ManagerUpsetException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public ManagerUpsetException(String message) {
+        super(message);
+    }
+}

core-java/src/main/java/com/baeldung/chainedexception/exceptions/NoLeaveGrantedException.java

@@ -0,0 +1,12 @@
+package com.baeldung.chainedexception.exceptions;
+
+public class NoLeaveGrantedException extends Exception {
+
+    public NoLeaveGrantedException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public NoLeaveGrantedException(String message) {
+        super(message);
+    }
+}

core-java/src/main/java/com/baeldung/chainedexception/exceptions/TeamLeadUpsetException.java

@@ -0,0 +1,12 @@
+package com.baeldung.chainedexception.exceptions;
+
+public class TeamLeadUpsetException extends Exception {
+
+    public TeamLeadUpsetException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public TeamLeadUpsetException(String message) {
+        super(message);
+    }
+}

core-java/src/main/java/com/baeldung/disruptor/DelayedMultiEventProducer.java

@@ -0,0 +1,34 @@
+package com.baeldung.disruptor;
+
+import com.lmax.disruptor.RingBuffer;
+
+public class DelayedMultiEventProducer implements EventProducer {
+
+    @Override
+    public void startProducing(final RingBuffer<ValueEvent> ringBuffer, final int count) {
+        final Runnable simpleProducer = () -> produce(ringBuffer, count, false);
+        final Runnable delayedProducer = () -> produce(ringBuffer, count, true);
+        new Thread(simpleProducer).start();
+        new Thread(delayedProducer).start();
+    }
+
+    private void produce(final RingBuffer<ValueEvent> ringBuffer, final int count, final boolean addDelay) {
+        for (int i = 0; i < count; i++) {
+            final long seq = ringBuffer.next();
+            final ValueEvent valueEvent = ringBuffer.get(seq);
+            valueEvent.setValue(i);
+            ringBuffer.publish(seq);
+            if (addDelay) {
+                addDelay();
+            }
+        }
+    }
+
+    private void addDelay() {
+        try {
+            Thread.sleep(1000);
+        } catch (InterruptedException interruptedException) {
+            // No-Op lets swallow it
+        }
+    }
+}

core-java/src/main/java/com/baeldung/disruptor/EventConsumer.java

@@ -0,0 +1,13 @@
+package com.baeldung.disruptor;
+
+import com.lmax.disruptor.EventHandler;
+
+/**
+ * Consumer that consumes event from ring buffer. 
+ */
+public interface EventConsumer {
+    /**
+     * One or more event handler to handle event from ring buffer. 
+     */
+    public EventHandler<ValueEvent>[] getEventHandler();
+}

core-java/src/main/java/com/baeldung/disruptor/EventProducer.java

@@ -0,0 +1,15 @@
+package com.baeldung.disruptor;
+
+import com.lmax.disruptor.RingBuffer;
+
+/**
+ * Producer that produces event for ring buffer.
+ */
+public interface EventProducer {
+    /**
+     * Start the producer that would start producing the values.
+     * @param ringBuffer
+     * @param count
+     */
+    public void startProducing(final RingBuffer<ValueEvent> ringBuffer, final int count);
+}

core-java/src/main/java/com/baeldung/disruptor/MultiEventPrintConsumer.java

@@ -0,0 +1,23 @@
+package com.baeldung.disruptor;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.lmax.disruptor.EventHandler;
+
+public class MultiEventPrintConsumer implements EventConsumer {
+
+    private final Logger logger = LoggerFactory.getLogger(this.getClass());
+    
+    @Override
+    @SuppressWarnings("unchecked")
+    public EventHandler<ValueEvent>[] getEventHandler() {
+        final EventHandler<ValueEvent> eventHandler = (event, sequence, endOfBatch) -> print(event.getValue(), sequence);
+        final EventHandler<ValueEvent> otherEventHandler = (event, sequence, endOfBatch) -> print(event.getValue(), sequence);
+        return new EventHandler[] { eventHandler, otherEventHandler };
+    }
+
+    private void print(final int id, final long sequenceId) {
+        logger.info("Id is " + id + " sequence id that was used is " + sequenceId);
+    }
+}

core-java/src/main/java/com/baeldung/disruptor/SingleEventPrintConsumer.java

@@ -0,0 +1,22 @@
+package com.baeldung.disruptor;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.lmax.disruptor.EventHandler;
+
+public class SingleEventPrintConsumer implements EventConsumer {
+
+    private final Logger logger = LoggerFactory.getLogger(this.getClass());
+    
+    @Override
+    @SuppressWarnings("unchecked")
+    public EventHandler<ValueEvent>[] getEventHandler() {
+        final EventHandler<ValueEvent> eventHandler = (event, sequence, endOfBatch) -> print(event.getValue(), sequence);
+        return new EventHandler[] { eventHandler };
+    }
+
+    private void print(final int id, final long sequenceId) {
+        logger.info("Id is " + id + " sequence id that was used is " + sequenceId);
+    }
+}

core-java/src/main/java/com/baeldung/disruptor/SingleEventProducer.java

@@ -0,0 +1,22 @@
+package com.baeldung.disruptor;
+
+import com.lmax.disruptor.RingBuffer;
+
+public class SingleEventProducer implements EventProducer {
+
+    @Override
+    public void startProducing(RingBuffer<ValueEvent> ringBuffer, int count) {
+        final Runnable producer = () -> produce(ringBuffer, count);
+        new Thread(producer).start();
+    }
+
+    private void produce(final RingBuffer<ValueEvent> ringBuffer, final int count) {
+        for (int i = 0; i < count; i++) {
+            final long seq = ringBuffer.next();
+            final ValueEvent valueEvent = ringBuffer.get(seq);
+            valueEvent.setValue(i);
+            ringBuffer.publish(seq);
+        }
+    }
+
+}

core-java/src/main/java/com/baeldung/disruptor/ValueEvent.java

@@ -0,0 +1,25 @@
+package com.baeldung.disruptor;
+
+import org.apache.commons.lang3.builder.ToStringBuilder;
+
+import com.lmax.disruptor.EventFactory;
+
+public final class ValueEvent {
+
+    private int value;
+
+    public int getValue() {
+        return value;
+    }
+
+    public void setValue(int value) {
+        this.value = value;
+    }
+
+    public final static EventFactory<ValueEvent> EVENT_FACTORY = () -> new ValueEvent();
+
+    @Override
+    public String toString() {
+        return ToStringBuilder.reflectionToString(this);
+    }
+}

core-java/src/main/java/com/baeldung/java8/lambda/exceptions/LambdaExceptionWrappers.java

@@ -0,0 +1,57 @@
+package com.baeldung.java8.lambda.exceptions;
+
+import java.util.function.Consumer;
+
+public class LambdaExceptionWrappers {
+
+    public static Consumer<Integer> lambdaWrapper(Consumer<Integer> consumer) {
+        return i -> {
+            try {
+                consumer.accept(i);
+            } catch (ArithmeticException e) {
+                System.err.println("Arithmetic Exception occured : " + e.getMessage());
+            }
+        };
+    }
+
+    static <T, E extends Exception> Consumer<T> consumerWrapper(Consumer<T> consumer, Class<E> clazz) {
+        return i -> {
+            try {
+                consumer.accept(i);
+            } catch (Exception ex) {
+                try {
+                    E exCast = clazz.cast(ex);
+                    System.err.println("Exception occured : " + exCast.getMessage());
+                } catch (ClassCastException ccEx) {
+                    throw ex;
+                }
+            }
+        };
+    }
+
+    public static <T> Consumer<T> throwingConsumerWrapper(ThrowingConsumer<T, Exception> throwingConsumer) {
+        return i -> {
+            try {
+                throwingConsumer.accept(i);
+            } catch (Exception ex) {
+                throw new RuntimeException(ex);
+            }
+        };
+    }
+
+    public static <T, E extends Exception> Consumer<T> handlingConsumerWrapper(ThrowingConsumer<T, E> throwingConsumer, Class<E> exceptionClass) {
+        return i -> {
+            try {
+                throwingConsumer.accept(i);
+            } catch (Exception ex) {
+                try {
+                    E exCast = exceptionClass.cast(ex);
+                    System.err.println("Exception occured : " + exCast.getMessage());
+                } catch (ClassCastException ccEx) {
+                    throw new RuntimeException(ex);
+                }
+            }
+        };
+    }
+
+}

core-java/src/main/java/com/baeldung/java8/lambda/exceptions/ThrowingConsumer.java

@@ -0,0 +1,8 @@
+package com.baeldung.java8.lambda.exceptions;
+
+@FunctionalInterface
+public interface ThrowingConsumer<T, E extends Exception> {
+
+    void accept(T t) throws E;
+
+}

core-java/src/test/java/com/baeldung/disruptor/DisruptorTest.java

@@ -0,0 +1,83 @@
+package com.baeldung.disruptor;
+
+import java.util.concurrent.ThreadFactory;
+import org.junit.Before;
+import org.junit.Test;
+import com.lmax.disruptor.BusySpinWaitStrategy;
+import com.lmax.disruptor.RingBuffer;
+import com.lmax.disruptor.WaitStrategy;
+import com.lmax.disruptor.dsl.Disruptor;
+import com.lmax.disruptor.dsl.ProducerType;
+import com.lmax.disruptor.util.DaemonThreadFactory;
+
+public class DisruptorTest {
+    private Disruptor<ValueEvent> disruptor;
+    private WaitStrategy waitStrategy;
+
+    @Before
+    public void setUp() throws Exception {
+        waitStrategy = new BusySpinWaitStrategy();
+    }
+
+    private void createDisruptor(final ProducerType producerType, final EventConsumer eventConsumer) {
+        final ThreadFactory threadFactory = DaemonThreadFactory.INSTANCE;
+        disruptor = new Disruptor<ValueEvent>(ValueEvent.EVENT_FACTORY, 16, threadFactory, producerType, waitStrategy);
+        disruptor.handleEventsWith(eventConsumer.getEventHandler());
+    }
+
+    private void startProducing(final RingBuffer<ValueEvent> ringBuffer, final int count, final EventProducer eventProducer) {
+        eventProducer.startProducing(ringBuffer, count);
+    }
+
+    @Test
+    public void whenMultipleProducerSingleConsumer_thenOutputInFifoOrder() {
+        final EventConsumer eventConsumer = new SingleEventPrintConsumer();
+        final EventProducer eventProducer = new DelayedMultiEventProducer();
+        createDisruptor(ProducerType.MULTI, eventConsumer);
+        final RingBuffer<ValueEvent> ringBuffer = disruptor.start();
+
+        startProducing(ringBuffer, 32, eventProducer);
+
+        disruptor.halt();
+        disruptor.shutdown();
+    }
+
+    @Test
+    public void whenSingleProducerSingleConsumer_thenOutputInFifoOrder() {
+        final EventConsumer eventConsumer = new SingleEventConsumer();
+        final EventProducer eventProducer = new SingleEventProducer();
+        createDisruptor(ProducerType.SINGLE, eventConsumer);
+        final RingBuffer<ValueEvent> ringBuffer = disruptor.start();
+
+        startProducing(ringBuffer, 32, eventProducer);
+
+        disruptor.halt();
+        disruptor.shutdown();
+    }
+
+    @Test
+    public void whenSingleProducerMultipleConsumer_thenOutputInFifoOrder() {
+        final EventConsumer eventConsumer = new MultiEventConsumer();
+        final EventProducer eventProducer = new SingleEventProducer();
+        createDisruptor(ProducerType.SINGLE, eventConsumer);
+        final RingBuffer<ValueEvent> ringBuffer = disruptor.start();
+
+        startProducing(ringBuffer, 32, eventProducer);
+
+        disruptor.halt();
+        disruptor.shutdown();
+    }
+
+    @Test
+    public void whenMultipleProducerMultipleConsumer_thenOutputInFifoOrder() {
+        final EventConsumer eventConsumer = new MultiEventPrintConsumer();
+        final EventProducer eventProducer = new DelayedMultiEventProducer();
+        createDisruptor(ProducerType.MULTI, eventConsumer);
+        final RingBuffer<ValueEvent> ringBuffer = disruptor.start();
+
+        startProducing(ringBuffer, 32, eventProducer);
+
+        disruptor.halt();
+        disruptor.shutdown();
+    }
+}

core-java/src/test/java/com/baeldung/disruptor/MultiEventConsumer.java

@@ -0,0 +1,27 @@
+package com.baeldung.disruptor;
+
+import static org.junit.Assert.assertEquals;
+
+import com.lmax.disruptor.EventHandler;
+
+public class MultiEventConsumer implements EventConsumer {
+
+    private int expectedValue = -1;
+    private int otherExpectedValue = -1;
+
+    @Override
+    @SuppressWarnings("unchecked")
+    public EventHandler<ValueEvent>[] getEventHandler() {
+        final EventHandler<ValueEvent> eventHandler = (event, sequence, endOfBatch) -> assertExpectedValue(event.getValue());
+        final EventHandler<ValueEvent> otherEventHandler = (event, sequence, endOfBatch) -> assertOtherExpectedValue(event.getValue());
+        return new EventHandler[] { eventHandler, otherEventHandler };
+    }
+
+    private void assertExpectedValue(final int id) {
+        assertEquals(++expectedValue, id);
+    }
+
+    private void assertOtherExpectedValue(final int id) {
+        assertEquals(++otherExpectedValue, id);
+    }
+}

core-java/src/test/java/com/baeldung/disruptor/SingleEventConsumer.java

@@ -0,0 +1,21 @@
+package com.baeldung.disruptor;
+
+import static org.junit.Assert.assertEquals;
+
+import com.lmax.disruptor.EventHandler;
+
+public class SingleEventConsumer implements EventConsumer {
+
+    private int expectedValue = -1;
+
+    @Override
+    @SuppressWarnings("unchecked")
+    public EventHandler<ValueEvent>[] getEventHandler() {
+        final EventHandler<ValueEvent> eventHandler = (event, sequence, endOfBatch) -> assertExpectedValue(event.getValue());
+        return new EventHandler[] { eventHandler };
+    }
+
+    private void assertExpectedValue(final int id) {
+        assertEquals(++expectedValue, id);
+    }
+}

core-java/src/test/java/com/baeldung/guava/GuavaBiMapTest.java

@@ -0,0 +1,120 @@
+package com.baeldung.guava;
+
+import static org.junit.Assert.*;
+import java.util.HashMap;
+import java.util.Map;
+import org.junit.Test;
+import com.google.common.collect.BiMap;
+import com.google.common.collect.EnumHashBiMap;
+import com.google.common.collect.HashBiMap;
+import com.google.common.collect.ImmutableBiMap;
+
+public class GuavaBiMapTest {
+    @Test
+    public void whenQueryByValue_returnsKey() {
+        final BiMap<String, String> capitalCountryBiMap = HashBiMap.create();
+        capitalCountryBiMap.put("New Delhi", "India");
+        capitalCountryBiMap.put("Washingon, D.C.", "USA");
+        capitalCountryBiMap.put("Moscow", "Russia");
+
+        final String countryCapitalName = capitalCountryBiMap.inverse().get("India");
+
+        assertEquals("New Delhi", countryCapitalName);
+    }
+
+    @Test
+    public void whenCreateBiMapFromExistingMap_returnsKey() {
+        final Map<String, String> capitalCountryMap = new HashMap<>();
+        capitalCountryMap.put("New Delhi", "India");
+        capitalCountryMap.put("Washingon, D.C.", "USA");
+        capitalCountryMap.put("Moscow", "Russia");
+        final BiMap<String, String> capitalCountryBiMap = HashBiMap.create(capitalCountryMap);
+
+        final String countryCapitalName = capitalCountryBiMap.inverse().get("India");
+
+        assertEquals("New Delhi", countryCapitalName);
+    }
+
+    @Test
+    public void whenQueryByKey_returnsValue() {
+        final BiMap<String, String> capitalCountryBiMap = HashBiMap.create();
+
+        capitalCountryBiMap.put("New Delhi", "India");
+        capitalCountryBiMap.put("Washingon, D.C.", "USA");
+        capitalCountryBiMap.put("Moscow", "Russia");
+
+        assertEquals("USA", capitalCountryBiMap.get("Washingon, D.C."));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void whenSameValueIsPresent_throwsException() {
+        final BiMap<String, String> capitalCountryBiMap = HashBiMap.create();
+
+        capitalCountryBiMap.put("New Delhi", "India");
+        capitalCountryBiMap.put("Washingon, D.C.", "USA");
+        capitalCountryBiMap.put("Moscow", "Russia");
+        capitalCountryBiMap.put("Trump", "USA");
+    }
+
+    @Test
+    public void givenSameValueIsPresent_whenForcePut_completesSuccessfully() {
+        final BiMap<String, String> capitalCountryBiMap = HashBiMap.create();
+
+        capitalCountryBiMap.put("New Delhi", "India");
+        capitalCountryBiMap.put("Washingon, D.C.", "USA");
+        capitalCountryBiMap.put("Moscow", "Russia");
+        capitalCountryBiMap.forcePut("Trump", "USA");
+
+        assertEquals("USA", capitalCountryBiMap.get("Trump"));
+        assertEquals("Trump", capitalCountryBiMap.inverse().get("USA"));
+    }
+
+    @Test
+    public void whenSameKeyIsPresent_replacesAlreadyPresent() {
+        final BiMap<String, String> capitalCountryBiMap = HashBiMap.create();
+
+        capitalCountryBiMap.put("New Delhi", "India");
+        capitalCountryBiMap.put("Washingon, D.C.", "USA");
+        capitalCountryBiMap.put("Moscow", "Russia");
+        capitalCountryBiMap.put("Washingon, D.C.", "HongKong");
+
+        assertEquals("HongKong", capitalCountryBiMap.get("Washingon, D.C."));
+    }
+
+    @Test
+    public void whenUsingImmutableBiMap_allowsPutSuccessfully() {
+        final BiMap<String, String> capitalCountryBiMap = new ImmutableBiMap.Builder<String, String>().put("New Delhi", "India").put("Washingon, D.C.", "USA").put("Moscow", "Russia").build();
+
+        assertEquals("USA", capitalCountryBiMap.get("Washingon, D.C."));
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void whenUsingImmutableBiMap_doesntAllowRemove() {
+        final BiMap<String, String> capitalCountryBiMap = new ImmutableBiMap.Builder<String, String>().put("New Delhi", "India").put("Washingon, D.C.", "USA").put("Moscow", "Russia").build();
+
+        capitalCountryBiMap.remove("New Delhi");
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void whenUsingImmutableBiMap_doesntAllowPut() {
+        final BiMap<String, String> capitalCountryBiMap = new ImmutableBiMap.Builder<String, String>().put("New Delhi", "India").put("Washingon, D.C.", "USA").put("Moscow", "Russia").build();
+
+        capitalCountryBiMap.put("New York", "USA");
+    }
+
+    private enum Operation {
+        ADD, SUBTRACT, MULTIPLY, DIVIDE
+    }
+
+    @Test
+    public void whenUsingEnumAsKeyInMap_replacesAlreadyPresent() {
+        final BiMap<Operation, String> operationStringBiMap = EnumHashBiMap.create(Operation.class);
+
+        operationStringBiMap.put(Operation.ADD, "Add");
+        operationStringBiMap.put(Operation.SUBTRACT, "Subtract");
+        operationStringBiMap.put(Operation.MULTIPLY, "Multiply");
+        operationStringBiMap.put(Operation.DIVIDE, "Divide");
+
+        assertEquals("Divide", operationStringBiMap.get(Operation.DIVIDE));
+    }
+}

core-java/src/test/java/com/baeldung/java/conversion/IterableStreamConversionTest.java

@@ -0,0 +1,32 @@
+package com.baeldung.java.conversion;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.collection.IsIterableContainingInOrder.contains;
+
+public class IterableStreamConversionTest {
+
+    @Test
+    public void givenIterable_whenConvertedToStream_thenNotNull() {
+        Iterable<String> iterable = Arrays.asList("Testing", "Iterable", "conversion", "to", "Stream");
+
+        Assert.assertNotNull(StreamSupport.stream(iterable.spliterator(), false));
+    }
+
+    @Test
+    public void whenConvertedToList_thenCorrect() {
+        Iterable<String> iterable = Arrays.asList("Testing", "Iterable", "conversion", "to", "Stream");
+
+        List<String> result = StreamSupport.stream(iterable.spliterator(), false)
+          .map(String::toUpperCase).collect(Collectors.toList());
+
+        assertThat(result, contains("TESTING", "ITERABLE", "CONVERSION", "TO", "STREAM"));
+    }
+}

core-java/src/test/java/com/baeldung/java8/Java8FindAnyFindFirstTest.java

@@ -0,0 +1,38 @@
+package com.baeldung.java8;
+
+
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+
+import static org.hamcrest.Matchers.anyOf;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+public class Java8FindAnyFindFirstTest {
+
+    @Test
+    public void createStream_whenFindAnyResultIsPresent_thenCorrect() {
+
+        List<String> list = Arrays.asList("A","B","C","D");
+
+        Optional<String> result = list.stream().findAny();
+
+        assertTrue(result.isPresent());
+        assertThat(result.get(), anyOf(is("A"), is("B"), is("C"), is("D")));
+    }
+
+    @Test
+    public void createStream_whenFindFirstResultIsPresent_thenCorrect() {
+
+        List<String> list = Arrays.asList("A","B","C","D");
+
+        Optional<String> result = list.stream().findFirst();
+
+        assertTrue(result.isPresent());
+        assertThat(result.get(),is("A"));
+    }
+}

core-java/src/test/java/com/baeldung/java8/lambda/exceptions/LambdaExceptionWrappersTest.java

@@ -0,0 +1,46 @@
+package com.baeldung.java8.lambda.exceptions;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.List;
+
+import static com.baeldung.java8.lambda.exceptions.LambdaExceptionWrappers.*;
+
+public class LambdaExceptionWrappersTest {
+
+    private List<Integer> integers;
+
+    @Before
+    public void init() {
+        integers = Arrays.asList(3, 9, 7, 0, 10, 20);
+    }
+
+    @Test
+    public void whenNoExceptionFromLambdaWrapper_thenSuccess() {
+        integers.forEach(lambdaWrapper(i -> System.out.println(50 / i)));
+    }
+
+    @Test
+    public void whenNoExceptionFromConsumerWrapper_thenSuccess() {
+        integers.forEach(consumerWrapper(i -> System.out.println(50 / i), ArithmeticException.class));
+    }
+
+    @Test(expected = RuntimeException.class)
+    public void whenExceptionFromThrowingConsumerWrapper_thenSuccess() {
+        integers.forEach(throwingConsumerWrapper(i -> writeToFile(i)));
+    }
+
+    @Test
+    public void whenNoExceptionFromHandlingConsumerWrapper_thenSuccess() {
+        integers.forEach(handlingConsumerWrapper(i -> writeToFile(i), IOException.class));
+    }
+
+    private void writeToFile(Integer i) throws IOException {
+        if (i == 0) {
+            throw new IOException(); // mock IOException
+        }
+    }
+}

core-java/src/test/java/org/baeldung/java/collections/README.md

@@ -1,2 +1,3 @@
 ### Relevant Articles:
 - [Join and Split Arrays and Collections in Java](http://www.baeldung.com/java-join-and-split)
+- [Introduction to Java Servlets](http://www.baeldung.com/intro-to-servlets)

core-java/src/test/java/org/baeldung/java/io/JavaInputStreamToXUnitTest.java

@@ -1,38 +1,26 @@
 package org.baeldung.java.io;
 
-import static org.apache.commons.lang3.RandomStringUtils.randomAlphabetic;
-import static org.hamcrest.Matchers.equalTo;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertThat;
-
-import java.io.BufferedReader;
-import java.io.ByteArrayInputStream;
-import java.io.ByteArrayOutputStream;
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.InputStreamReader;
-import java.io.OutputStream;
-import java.io.Reader;
-import java.io.StringWriter;
-import java.nio.charset.Charset;
-import java.nio.charset.StandardCharsets;
-import java.nio.file.StandardCopyOption;
-import java.util.Scanner;
-
-import org.apache.commons.io.FileUtils;
-import org.apache.commons.io.IOUtils;
-import org.junit.Test;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 import com.google.common.base.Charsets;
 import com.google.common.io.ByteSource;
 import com.google.common.io.ByteStreams;
 import com.google.common.io.CharStreams;
 import com.google.common.io.Files;
+import org.apache.commons.io.FileUtils;
+import org.apache.commons.io.IOUtils;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.*;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.StandardCopyOption;
+import java.util.Scanner;
+
+import static org.apache.commons.lang3.RandomStringUtils.randomAlphabetic;
+import static org.hamcrest.Matchers.equalTo;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
 
 @SuppressWarnings("unused")
 public class JavaInputStreamToXUnitTest {
@@ -163,7 +151,7 @@ public class JavaInputStreamToXUnitTest {
     // tests - InputStream to File
 
     @Test
-    public final void givenUsingPlainJava_whenConvertingAnFullInputStreamToAFile_thenCorrect() throws IOException {
+    public final void whenConvertingToFile_thenCorrect() throws IOException {
         final InputStream initialStream = new FileInputStream(new File("src/main/resources/sample.txt"));
         final byte[] buffer = new byte[initialStream.available()];
         initialStream.read(buffer);
@@ -177,7 +165,7 @@ public class JavaInputStreamToXUnitTest {
     }
 
     @Test
-    public final void givenUsingPlainJava_whenConvertingAnInProgressInputStreamToAFile_thenCorrect() throws IOException {
+    public final void whenConvertingInProgressToFile_thenCorrect() throws IOException {
         final InputStream initialStream = new FileInputStream(new File("src/main/resources/sample.txt"));
         final File targetFile = new File("src/main/resources/targetFile.tmp");
         final OutputStream outStream = new FileOutputStream(targetFile);
@@ -193,7 +181,7 @@ public class JavaInputStreamToXUnitTest {
     }
 
     @Test
-    public final void givenUsingPlainJava8_whenConvertingAnInProgressInputStreamToAFile_thenCorrect() throws IOException {
+    public final void whenConvertingAnInProgressInputStreamToFile_thenCorrect2() throws IOException {
         final InputStream initialStream = new FileInputStream(new File("src/main/resources/sample.txt"));
         final File targetFile = new File("src/main/resources/targetFile.tmp");
 
@@ -203,7 +191,7 @@ public class JavaInputStreamToXUnitTest {
     }
 
     @Test
-    public final void givenUsingGuava_whenConvertingAnInputStreamToAFile_thenCorrect() throws IOException {
+    public final void whenConvertingInputStreamToFile_thenCorrect3() throws IOException {
         final InputStream initialStream = new FileInputStream(new File("src/main/resources/sample.txt"));
         final byte[] buffer = new byte[initialStream.available()];
         initialStream.read(buffer);
@@ -215,7 +203,7 @@ public class JavaInputStreamToXUnitTest {
     }
 
     @Test
-    public final void givenUsingCommonsIO_whenConvertingAnInputStreamToAFile_thenCorrect() throws IOException {
+    public final void whenConvertingInputStreamToFile_thenCorrect4() throws IOException {
         final InputStream initialStream = FileUtils.openInputStream(new File("src/main/resources/sample.txt"));
 
         final File targetFile = new File("src/main/resources/targetFile.tmp");

deltaspike/pom.xml

@@ -19,11 +19,10 @@
     </licenses>
 
     <properties>
-        <!-- Explicitly declaring the source encoding eliminates the following 
+        <!-- Explicitly declaring the source encoding eliminates the following message: -->
-            message: -->
+        <!-- [WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent! -->
-        <!-- [WARNING] Using platform encoding (UTF-8 actually) to copy filtered 
+        <project.build.sourceEncoding>
-            resources, i.e. build is platform dependent! -->
+            UTF-8</project.build.sourceEncoding>
-        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 
         <slf4j.version>1.7.21</slf4j.version>
         <querydsl.version>3.7.4</querydsl.version>
@@ -32,8 +31,7 @@
         <!-- JBoss dependency versions -->
         <wildfly.maven.plugin.version>1.0.2.Final</wildfly.maven.plugin.version>
 
-        <!-- Define the version of the JBoss BOMs we want to import to specify 
+        <!-- Define the version of the JBoss BOMs we want to import to specify tested stacks. -->
-            tested stacks. -->
         <jboss.bom.version>8.2.2.Final</jboss.bom.version>
 
         <!-- other plugin versions -->
@@ -50,14 +48,11 @@
 
     <dependencyManagement>
         <dependencies>
-            <!-- JBoss distributes a complete set of Java EE 7 APIs including a Bill
+            <!-- JBoss distributes a complete set of Java EE 7 APIs including a Bill of Materials (BOM). A BOM specifies the versions of a "stack" 
-                of Materials (BOM). A BOM specifies the versions of a "stack" (or a collection) 
+                (or a collection) of artifacts. We use this here so that we always get the correct versions of artifacts. Here we use the jboss-javaee-7.0-with-tools 
-                of artifacts. We use this here so that we always get the correct versions 
+                stack (you can read this as the JBoss stack of the Java EE 7 APIs, with some extras tools for your project, such as Arquillian for testing) and 
-                of artifacts. Here we use the jboss-javaee-7.0-with-tools stack (you can
+                the jboss-javaee-7.0-with-hibernate stack you can read this as the JBoss stack of the Java EE 7 APIs, with extras from the Hibernate family of 
-                read this as the JBoss stack of the Java EE 7 APIs, with some extras tools
+                projects) -->
-                for your project, such as Arquillian for testing) and the jboss-javaee-7.0-with-hibernate
-                stack you can read this as the JBoss stack of the Java EE 7 APIs, with extras
-                from the Hibernate family of projects) -->
             <dependency>
                 <groupId>org.wildfly.bom</groupId>
                 <artifactId>jboss-javaee-7.0-with-tools</artifactId>
@@ -77,43 +72,37 @@
 
     <dependencies>
 
-        <!-- First declare the APIs we depend on and need for compilation. All 
+        <!-- First declare the APIs we depend on and need for compilation. All of them are provided by JBoss WildFly -->
-            of them are provided by JBoss WildFly -->
 
-        <!-- Import the CDI API, we use provided scope as the API is included in 
+        <!-- Import the CDI API, we use provided scope as the API is included in JBoss WildFly -->
-            JBoss WildFly -->
         <dependency>
             <groupId>javax.enterprise</groupId>
             <artifactId>cdi-api</artifactId>
             <scope>provided</scope>
         </dependency>
 
-        <!-- Import the Common Annotations API (JSR-250), we use provided scope 
+        <!-- Import the Common Annotations API (JSR-250), we use provided scope as the API is included in JBoss WildFly -->
-            as the API is included in JBoss WildFly -->
         <dependency>
             <groupId>org.jboss.spec.javax.annotation</groupId>
             <artifactId>jboss-annotations-api_1.2_spec</artifactId>
             <scope>provided</scope>
         </dependency>
 
-        <!-- Import the JAX-RS API, we use provided scope as the API is included 
+        <!-- Import the JAX-RS API, we use provided scope as the API is included in JBoss WildFly -->
-            in JBoss WildFly -->
         <dependency>
             <groupId>org.jboss.resteasy</groupId>
             <artifactId>jaxrs-api</artifactId>
             <scope>provided</scope>
         </dependency>
 
-        <!-- Import the JPA API, we use provided scope as the API is included in 
+        <!-- Import the JPA API, we use provided scope as the API is included in JBoss WildFly -->
-            JBoss WildFly -->
         <dependency>
             <groupId>org.hibernate.javax.persistence</groupId>
             <artifactId>hibernate-jpa-2.1-api</artifactId>
             <scope>provided</scope>
         </dependency>
 
-        <!-- Import the EJB API, we use provided scope as the API is included in 
+        <!-- Import the EJB API, we use provided scope as the API is included in JBoss WildFly -->
-            JBoss WildFly -->
         <dependency>
             <groupId>org.jboss.spec.javax.ejb</groupId>
             <artifactId>jboss-ejb-api_3.2_spec</artifactId>
@@ -135,8 +124,7 @@
             </exclusions>
         </dependency>
 
-        <!-- Import the JSF API, we use provided scope as the API is included in 
+        <!-- Import the JSF API, we use provided scope as the API is included in JBoss WildFly -->
-            JBoss WildFly -->
         <dependency>
             <groupId>org.jboss.spec.javax.faces</groupId>
             <artifactId>jboss-jsf-api_2.2_spec</artifactId>
@@ -145,16 +133,14 @@
 
         <!-- Now we declare any tools needed -->
 
-        <!-- Annotation processor to generate the JPA 2.0 metamodel classes for 
+        <!-- Annotation processor to generate the JPA 2.0 metamodel classes for typesafe criteria queries -->
-            typesafe criteria queries -->
         <dependency>
             <groupId>org.hibernate</groupId>
             <artifactId>hibernate-jpamodelgen</artifactId>
             <scope>provided</scope>
         </dependency>
 
-        <!-- Annotation processor that raising compilation errors whenever constraint 
+        <!-- Annotation processor that raising compilation errors whenever constraint annotations are incorrectly used. -->
-            annotations are incorrectly used. -->
         <dependency>
             <groupId>org.hibernate</groupId>
             <artifactId>hibernate-validator-annotation-processor</artifactId>
@@ -169,8 +155,7 @@
         </dependency>
 
         <!-- Optional, but highly recommended -->
-        <!-- Arquillian allows you to test enterprise code such as EJBs and Transactional(JTA) 
+        <!-- Arquillian allows you to test enterprise code such as EJBs and Transactional(JTA) JPA from JUnit/TestNG -->
-            JPA from JUnit/TestNG -->
         <dependency>
             <groupId>org.jboss.arquillian.junit</groupId>
             <artifactId>arquillian-junit-container</artifactId>
@@ -225,8 +210,7 @@
     </dependencies>
 
     <build>
-        <!-- Maven will append the version to the finalName (which is the name 
+        <!-- Maven will append the version to the finalName (which is the name given to the generated war, and hence the context root) -->
-            given to the generated war, and hence the context root) -->
         <finalName>${project.artifactId}</finalName>
         <plugins>
             <plugin>
@@ -265,10 +249,8 @@
 
     <profiles>
         <profile>
-            <!-- The default profile skips all tests, though you can tune it to run 
+            <!-- The default profile skips all tests, though you can tune it to run just unit tests based on a custom pattern -->
-                just unit tests based on a custom pattern -->
+            <!-- Seperate profiles are provided for running all tests, including Arquillian tests that execute in the specified container -->
-            <!-- Seperate profiles are provided for running all tests, including Arquillian 
-                tests that execute in the specified container -->
             <id>default</id>
             <activation>
                 <activeByDefault>true</activeByDefault>
@@ -288,10 +270,8 @@
 
         <profile>
 
-            <!-- An optional Arquillian testing profile that executes tests
+            <!-- An optional Arquillian testing profile that executes tests in your WildFly instance -->
-                in your WildFly instance -->
+            <!-- This profile will start a new WildFly instance, and execute the test, shutting it down when done -->
-            <!-- This profile will start a new WildFly instance, and execute the
-                test, shutting it down when done -->
             <!-- Run with: mvn clean test -Parq-wildfly-managed -->
             <id>arq-wildfly-managed</id>
             <dependencies>

enterprise-patterns/pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
 

gradle/build.gradle

@@ -0,0 +1,25 @@
+apply plugin: 'java'
+apply plugin: 'maven'
+
+repositories{
+   mavenCentral()
+}
+
+dependencies{ 
+     compile 'org.springframework:spring-context:4.3.5.RELEASE' 
+} 
+
+task hello {   
+    println "this Baeldung's tutorial is ${awesomeness}"  
+}
+
+uploadArchives {  
+    repositories {  
+        mavenDeployer {  
+            repository(url: 'http://yourmavenrepo/repository') {  
+                authentication(userName: 'user', password: 'password');  
+            }  
+      
+        }  
+    }  
+}

gradle/gradle.properties

@@ -0,0 +1,3 @@
+awesomeness=awesome
+group=com.baeldung.tutorial
+version=1.0.1

gradle/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,6 @@
+#Sat Dec 31 15:46:08 BRT 2016
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-3.2.1-bin.zip

gradle/gradlew

@@ -0,0 +1,160 @@
+#!/usr/bin/env bash
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn ( ) {
+    echo "$*"
+}
+
+die ( ) {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+esac
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Split up the JVM_OPTS And GRADLE_OPTS values into an array, following the shell quoting and substitution rules
+function splitJvmOpts() {
+    JVM_OPTS=("$@")
+}
+eval splitJvmOpts $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS
+JVM_OPTS[${#JVM_OPTS[*]}]="-Dorg.gradle.appname=$APP_BASE_NAME"
+
+exec "$JAVACMD" "${JVM_OPTS[@]}" -classpath "$CLASSPATH" org.gradle.wrapper.GradleWrapperMain "$@"

gradle/gradlew.bat

@@ -0,0 +1,90 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windowz variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+if "%@eval[2+2]" == "4" goto 4NT_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+goto execute
+
+:4NT_args
+@rem Get arguments from the 4NT Shell from JP Software
+set CMD_LINE_ARGS=%$
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

gradle/src/main/java/Main.java

@@ -0,0 +1,5 @@
+public class Main{
+    public static void main(String[] args){
+        System.out.println("Baeldung Rocks");
+    }
+}

guava/pom.xml

@@ -92,7 +92,7 @@
 
     <properties>
         <!-- util -->
-        <guava.version>19.0</guava.version>
+        <guava.version>21.0</guava.version>
         <commons-lang3.version>3.5</commons-lang3.version>
         <commons-collections4.version>4.1</commons-collections4.version>
 

guava/src/test/java/org/baeldung/guava/GuavaMultiMapTest.java

@@ -0,0 +1,63 @@
+package org.baeldung.guava;
+
+import com.google.common.collect.ArrayListMultimap;
+import com.google.common.collect.Multimap;
+import org.junit.Test;
+
+import java.util.LinkedHashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.Assert.assertEquals;
+
+
+public class GuavaMultiMapTest {
+
+    @Test
+    public void givenMap_whenAddTwoValuesForSameKey_shouldOverridePreviousKey() {
+        //given
+        String key = "a-key";
+        Map<String, String> map = new LinkedHashMap<>();
+
+        //when
+        map.put(key, "firstValue");
+        map.put(key, "secondValue");
+
+        //then
+        assertEquals(1, map.size());
+    }
+
+    @Test
+    public void givenMultiMap_whenAddTwoValuesForSameKey_shouldHaveTwoEntriesInMap() {
+        //given
+        String key = "a-key";
+        Multimap<String, String> map = ArrayListMultimap.create();
+
+        //when
+        map.put(key, "firstValue");
+        map.put(key, "secondValue");
+
+        //then
+        assertEquals(2, map.size());
+    }
+
+    @Test
+    public void givenMapOfListValues_whenAddTwoValuesForSameKey_shouldHaveTwoElementsInList() {
+        //given
+        String key = "a-key";
+        Map<String, List<String>> map = new LinkedHashMap<>();
+
+        //when
+        List<String> values = map.get(key);
+        if(values == null){
+            values = new LinkedList<>();
+            values.add("firstValue");
+            values.add("secondValue");
+        }
+        map.put(key, values);
+
+        //then
+        assertEquals(1, map.size());
+    }
+}

guava/src/test/java/org/baeldung/guava/GuavaStringTest.java

@@ -8,10 +8,9 @@ import static org.junit.Assert.assertTrue;
 
 import java.nio.charset.Charset;
 import java.nio.charset.CharsetEncoder;
-import java.util.ArrayList;
+import java.util.*;
-import java.util.List;
-import java.util.Map;
 
+import com.google.common.collect.*;
 import org.junit.Test;
 
 import com.google.common.base.CharMatcher;
@@ -19,9 +18,6 @@ import com.google.common.base.Function;
 import com.google.common.base.Joiner;
 import com.google.common.base.Predicate;
 import com.google.common.base.Splitter;
-import com.google.common.collect.Iterables;
-import com.google.common.collect.Lists;
-import com.google.common.collect.Maps;
 
 public class GuavaStringTest {
 

httpclient/src/test/java/org/baeldung/httpclient/HttpClientMultipartLiveTest.java

@@ -28,13 +28,14 @@ import org.apache.http.impl.client.CloseableHttpClient;
 import org.apache.http.impl.client.HttpClientBuilder;
 import org.junit.After;
 import org.junit.Before;
-import org.junit.Ignore;
 import org.junit.Test;
 
-@Ignore("Server is not available")
 public class HttpClientMultipartLiveTest {
 
-    private static final String SERVER = "http://echo.200please.com";
+    // No longer available
+    // private static final String SERVER = "http://echo.200please.com";
+
+    private static final String SERVER = "http://posttestserver.com/post.php";
     private static final String TEXTFILENAME = "temp.txt";
     private static final String IMAGEFILENAME = "image.jpg";
     private static final String ZIPFILENAME = "zipFile.zip";
@@ -46,7 +47,8 @@ public class HttpClientMultipartLiveTest {
 
     @Before
     public final void before() {
-        client = HttpClientBuilder.create().build();
+        client = HttpClientBuilder.create()
+            .build();
         post = new HttpPost(SERVER);
     }
 
@@ -80,7 +82,9 @@ public class HttpClientMultipartLiveTest {
 
     @Test
     public final void givenFileandMultipleTextParts_whenUploadwithAddPart_thenNoExceptions() throws IOException {
-        final URL url = Thread.currentThread().getContextClassLoader().getResource("uploads/" + TEXTFILENAME);
+        final URL url = Thread.currentThread()
+            .getContextClassLoader()
+            .getResource("uploads/" + TEXTFILENAME);
 
         final File file = new File(url.getPath());
         final FileBody fileBody = new FileBody(file, ContentType.DEFAULT_BINARY);
@@ -97,11 +101,12 @@ public class HttpClientMultipartLiveTest {
         post.setEntity(entity);
         response = client.execute(post);
 
-        final int statusCode = response.getStatusLine().getStatusCode();
+        final int statusCode = response.getStatusLine()
+            .getStatusCode();
         final String responseString = getContent();
         final String contentTypeInHeader = getContentTypeHeader();
         assertThat(statusCode, equalTo(HttpStatus.SC_OK));
-        assertTrue(responseString.contains("Content-Type: multipart/form-data;"));
+        // assertTrue(responseString.contains("Content-Type: multipart/form-data;"));
         assertTrue(contentTypeInHeader.contains("Content-Type: multipart/form-data;"));
         System.out.println(responseString);
         System.out.println("POST Content Type: " + contentTypeInHeader);
@@ -109,7 +114,9 @@ public class HttpClientMultipartLiveTest {
 
     @Test
     public final void givenFileandTextPart_whenUploadwithAddBinaryBodyandAddTextBody_ThenNoExeption() throws ClientProtocolException, IOException {
-        final URL url = Thread.currentThread().getContextClassLoader().getResource("uploads/" + TEXTFILENAME);
+        final URL url = Thread.currentThread()
+            .getContextClassLoader()
+            .getResource("uploads/" + TEXTFILENAME);
         final File file = new File(url.getPath());
         final String message = "This is a multipart post";
         final MultipartEntityBuilder builder = MultipartEntityBuilder.create();
@@ -119,11 +126,12 @@ public class HttpClientMultipartLiveTest {
         final HttpEntity entity = builder.build();
         post.setEntity(entity);
         response = client.execute(post);
-        final int statusCode = response.getStatusLine().getStatusCode();
+        final int statusCode = response.getStatusLine()
+            .getStatusCode();
         final String responseString = getContent();
         final String contentTypeInHeader = getContentTypeHeader();
         assertThat(statusCode, equalTo(HttpStatus.SC_OK));
-        assertTrue(responseString.contains("Content-Type: multipart/form-data;"));
+        // assertTrue(responseString.contains("Content-Type: multipart/form-data;"));
         assertTrue(contentTypeInHeader.contains("Content-Type: multipart/form-data;"));
         System.out.println(responseString);
         System.out.println("POST Content Type: " + contentTypeInHeader);
@@ -131,8 +139,12 @@ public class HttpClientMultipartLiveTest {
 
     @Test
     public final void givenFileAndInputStreamandText_whenUploadwithAddBinaryBodyandAddTextBody_ThenNoException() throws ClientProtocolException, IOException {
-        final URL url = Thread.currentThread().getContextClassLoader().getResource("uploads/" + ZIPFILENAME);
+        final URL url = Thread.currentThread()
-        final URL url2 = Thread.currentThread().getContextClassLoader().getResource("uploads/" + IMAGEFILENAME);
+            .getContextClassLoader()
+            .getResource("uploads/" + ZIPFILENAME);
+        final URL url2 = Thread.currentThread()
+            .getContextClassLoader()
+            .getResource("uploads/" + IMAGEFILENAME);
         final InputStream inputStream = new FileInputStream(url.getPath());
         final File file = new File(url2.getPath());
         final String message = "This is a multipart post";
@@ -144,11 +156,12 @@ public class HttpClientMultipartLiveTest {
         final HttpEntity entity = builder.build();
         post.setEntity(entity);
         response = client.execute(post);
-        final int statusCode = response.getStatusLine().getStatusCode();
+        final int statusCode = response.getStatusLine()
+            .getStatusCode();
         final String responseString = getContent();
         final String contentTypeInHeader = getContentTypeHeader();
         assertThat(statusCode, equalTo(HttpStatus.SC_OK));
-        assertTrue(responseString.contains("Content-Type: multipart/form-data;"));
+        // assertTrue(responseString.contains("Content-Type: multipart/form-data;"));
         assertTrue(contentTypeInHeader.contains("Content-Type: multipart/form-data;"));
         System.out.println(responseString);
         System.out.println("POST Content Type: " + contentTypeInHeader);
@@ -166,11 +179,12 @@ public class HttpClientMultipartLiveTest {
         final HttpEntity entity = builder.build();
         post.setEntity(entity);
         response = client.execute(post);
-        final int statusCode = response.getStatusLine().getStatusCode();
+        final int statusCode = response.getStatusLine()
+            .getStatusCode();
         final String responseString = getContent();
         final String contentTypeInHeader = getContentTypeHeader();
         assertThat(statusCode, equalTo(HttpStatus.SC_OK));
-        assertTrue(responseString.contains("Content-Type: multipart/form-data;"));
+        // assertTrue(responseString.contains("Content-Type: multipart/form-data;"));
         assertTrue(contentTypeInHeader.contains("Content-Type: multipart/form-data;"));
         System.out.println(responseString);
         System.out.println("POST Content Type: " + contentTypeInHeader);
@@ -179,7 +193,8 @@ public class HttpClientMultipartLiveTest {
     // UTIL
 
     final String getContent() throws IOException {
-        rd = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
+        rd = new BufferedReader(new InputStreamReader(response.getEntity()
+            .getContent()));
         String body = "";
         String content = "";
         while ((body = rd.readLine()) != null) {
@@ -189,7 +204,9 @@ public class HttpClientMultipartLiveTest {
     }
 
     final String getContentTypeHeader() throws IOException {
-        return post.getEntity().getContentType().toString();
+        return post.getEntity()
+            .getContentType()
+            .toString();
     }
 
 }

httpclient/src/test/java/org/baeldung/httpclient/HttpsClientSslLiveTest.java

@@ -1,11 +1,24 @@
 package org.baeldung.httpclient;
 
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.junit.Assert.assertThat;
+
+import java.io.IOException;
+import java.security.GeneralSecurityException;
+
+import javax.net.ssl.SSLContext;
+import javax.net.ssl.SSLHandshakeException;
+
 import org.apache.http.HttpResponse;
 import org.apache.http.client.methods.HttpGet;
 import org.apache.http.conn.ClientConnectionManager;
 import org.apache.http.conn.scheme.Scheme;
 import org.apache.http.conn.scheme.SchemeRegistry;
-import org.apache.http.conn.ssl.*;
+import org.apache.http.conn.ssl.NoopHostnameVerifier;
+import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
+import org.apache.http.conn.ssl.SSLSocketFactory;
+import org.apache.http.conn.ssl.TrustSelfSignedStrategy;
+import org.apache.http.conn.ssl.TrustStrategy;
 import org.apache.http.impl.client.CloseableHttpClient;
 import org.apache.http.impl.client.DefaultHttpClient;
 import org.apache.http.impl.client.HttpClientBuilder;
@@ -15,14 +28,6 @@ import org.apache.http.ssl.SSLContextBuilder;
 import org.apache.http.ssl.SSLContexts;
 import org.junit.Test;
 
-import javax.net.ssl.SSLContext;
-import javax.net.ssl.SSLException;
-import java.io.IOException;
-import java.security.GeneralSecurityException;
-
-import static org.hamcrest.CoreMatchers.equalTo;
-import static org.junit.Assert.assertThat;
-
 /**
  * This test requires a localhost server over HTTPS <br>
  * It should only be manually run, not part of the automated build
@@ -35,13 +40,15 @@ public class HttpsClientSslLiveTest {
 
     // tests
 
-    @Test(expected = SSLException.class)
+    @Test(expected = SSLHandshakeException.class)
     public final void whenHttpsUrlIsConsumed_thenException() throws IOException {
-        final CloseableHttpClient httpClient = HttpClientBuilder.create().build();
+        final CloseableHttpClient httpClient = HttpClientBuilder.create()
+            .build();
 
         final HttpGet getMethod = new HttpGet(HOST_WITH_SSL);
         final HttpResponse response = httpClient.execute(getMethod);
-        assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
+        assertThat(response.getStatusLine()
+            .getStatusCode(), equalTo(200));
     }
 
     @SuppressWarnings("deprecation")
@@ -57,7 +64,8 @@ public class HttpsClientSslLiveTest {
 
         final HttpGet getMethod = new HttpGet(HOST_WITH_SSL);
         final HttpResponse response = httpClient.execute(getMethod);
-        assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
+        assertThat(response.getStatusLine()
+            .getStatusCode(), equalTo(200));
 
         httpClient.close();
     }
@@ -65,44 +73,62 @@ public class HttpsClientSslLiveTest {
     @Test
     public final void givenHttpClientAfter4_3_whenAcceptingAllCertificates_thenCanConsumeHttpsUriWithSelfSignedCertificate() throws IOException, GeneralSecurityException {
         final TrustStrategy acceptingTrustStrategy = (certificate, authType) -> true;
-        final SSLContext sslContext = SSLContexts.custom().loadTrustMaterial(null, acceptingTrustStrategy).build();
+        final SSLContext sslContext = SSLContexts.custom()
+            .loadTrustMaterial(null, acceptingTrustStrategy)
+            .build();
 
         final SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslContext, SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);
 
-        final CloseableHttpClient httpClient = HttpClients.custom().setHostnameVerifier(SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER).setSSLSocketFactory(sslsf).build();
+        final CloseableHttpClient httpClient = HttpClients.custom()
+            .setHostnameVerifier(SSLConnectionSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER)
+            .setSSLSocketFactory(sslsf)
+            .build();
 
         final HttpGet getMethod = new HttpGet(HOST_WITH_SSL);
         final HttpResponse response = httpClient.execute(getMethod);
-        assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
+        assertThat(response.getStatusLine()
+            .getStatusCode(), equalTo(200));
 
         httpClient.close();
     }
 
     @Test
     public final void givenHttpClientPost4_3_whenAcceptingAllCertificates_thenCanConsumeHttpsUriWithSelfSignedCertificate() throws IOException, GeneralSecurityException {
-        final SSLContextBuilder builder = new SSLContextBuilder();
+        final SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(null, new TrustSelfSignedStrategy())
-        builder.loadTrustMaterial(null, new TrustSelfSignedStrategy());
+            .build();
-        final SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(builder.build());
+        final NoopHostnameVerifier hostnameVerifier = new NoopHostnameVerifier();
-        final CloseableHttpClient httpClient = HttpClients.custom().setSSLSocketFactory(sslsf).build();
+
+        final SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslContext, hostnameVerifier);
+        final CloseableHttpClient httpClient = HttpClients.custom()
+            .setSSLHostnameVerifier(hostnameVerifier)
+            .setSSLSocketFactory(sslsf)
+            .build();
 
         // new
 
         final HttpGet getMethod = new HttpGet(HOST_WITH_SSL);
         final HttpResponse response = httpClient.execute(getMethod);
-        assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
+        assertThat(response.getStatusLine()
+            .getStatusCode(), equalTo(200));
+        httpClient.close();
+
     }
 
     @Test
     public final void givenIgnoringCertificates_whenHttpsUrlIsConsumed_thenCorrect() throws Exception {
-        SSLContext sslContext = new SSLContextBuilder()
+        final SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(null, (certificate, authType) -> true)
-          .loadTrustMaterial(null, (certificate, authType) -> true).build();
+            .build();
 
-        final CloseableHttpClient client = HttpClients.custom().setSSLContext(sslContext).setSSLHostnameVerifier(new NoopHostnameVerifier()).build();
+        final CloseableHttpClient client = HttpClients.custom()
+            .setSSLContext(sslContext)
+            .setSSLHostnameVerifier(new NoopHostnameVerifier())
+            .build();
         final HttpGet httpGet = new HttpGet(HOST_WITH_SSL);
         httpGet.setHeader("Accept", "application/xml");
 
         final HttpResponse response = client.execute(httpGet);
-        assertThat(response.getStatusLine().getStatusCode(), equalTo(200));
+        assertThat(response.getStatusLine()
+            .getStatusCode(), equalTo(200));
     }
 
 }

jackson/src/main/java/com/baeldung/jackson/inheritance/Event.java

@@ -0,0 +1,25 @@
+package com.baeldung.jackson.inheritance;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+
+@JsonTypeInfo(use = JsonTypeInfo.Id.MINIMAL_CLASS, include = JsonTypeInfo.As.PROPERTY, property = "eventType")
+abstract public class Event {
+    private final String id;
+    private final Long timestamp;
+
+    @JsonCreator
+    public Event(@JsonProperty("id") String id, @JsonProperty("timestamp") Long timestamp) {
+        this.id = id;
+        this.timestamp = timestamp;
+    }
+
+    public Long getTimestamp() {
+        return timestamp;
+    }
+
+    public String getId() {
+        return id;
+    }
+}

jackson/src/main/java/com/baeldung/jackson/inheritance/ItemIdAddedToUser.java

@@ -0,0 +1,31 @@
+package com.baeldung.jackson.inheritance;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonTypeName;
+
+@JsonTypeName("itemIdAddedToUser")
+@JsonIgnoreProperties("id")
+public class ItemIdAddedToUser extends Event {
+    private final String itemId;
+    private final Long quantity;
+
+    @JsonCreator
+    public ItemIdAddedToUser(@JsonProperty("id") String id,
+                             @JsonProperty("timestamp") Long timestamp,
+                             @JsonProperty("itemId") String itemId,
+                             @JsonProperty("quantity") Long quantity) {
+        super(id, timestamp);
+        this.itemId = itemId;
+        this.quantity = quantity;
+    }
+
+    public String getItemId() {
+        return itemId;
+    }
+
+    public Long getQuantity() {
+        return quantity;
+    }
+}

jackson/src/main/java/com/baeldung/jackson/inheritance/ItemIdRemovedFromUser.java

@@ -0,0 +1,29 @@
+package com.baeldung.jackson.inheritance;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonTypeName;
+
+@JsonTypeName("itemIdRemovedFromUser")
+public class ItemIdRemovedFromUser extends Event {
+    private final String itemId;
+    private final Long quantity;
+
+    @JsonCreator
+    public ItemIdRemovedFromUser(@JsonProperty("id") String id,
+                                 @JsonProperty("timestamp") Long timestamp,
+                                 @JsonProperty("itemId") String itemId,
+                                 @JsonProperty("quantity") Long quantity) {
+        super(id, timestamp);
+        this.itemId = itemId;
+        this.quantity = quantity;
+    }
+
+    public String getItemId() {
+        return itemId;
+    }
+
+    public Long getQuantity() {
+        return quantity;
+    }
+}

jackson/src/test/java/com/baeldung/jackson/dtos/withEnum/DistanceEnumSimple.java

@@ -0,0 +1,26 @@
+package com.baeldung.jackson.dtos.withEnum;
+
+public enum DistanceEnumSimple {
+    KILOMETER("km", 1000), MILE("miles", 1609.34), METER("meters", 1), INCH("inches", 0.0254), CENTIMETER("cm", 0.01), MILLIMETER("mm", 0.001);
+
+    private String unit;
+    private final double meters;
+
+    private DistanceEnumSimple(String unit, double meters) {
+        this.unit = unit;
+        this.meters = meters;
+    }
+
+    public double getMeters() {
+        return meters;
+    }
+
+    public String getUnit() {
+        return unit;
+    }
+
+    public void setUnit(String unit) {
+        this.unit = unit;
+    }
+
+}

jackson/src/test/java/com/baeldung/jackson/dtos/withEnum/DistanceEnumWithJsonFormat.java

@@ -0,0 +1,29 @@
+package com.baeldung.jackson.dtos.withEnum;
+
+import com.fasterxml.jackson.annotation.JsonFormat;
+
+@JsonFormat(shape = JsonFormat.Shape.OBJECT)
+public enum DistanceEnumWithJsonFormat {
+    KILOMETER("km", 1000), MILE("miles", 1609.34), METER("meters", 1), INCH("inches", 0.0254), CENTIMETER("cm", 0.01), MILLIMETER("mm", 0.001);
+
+    private String unit;
+    private final double meters;
+
+    private DistanceEnumWithJsonFormat(String unit, double meters) {
+        this.unit = unit;
+        this.meters = meters;
+    }
+
+    public double getMeters() {
+        return meters;
+    }
+
+    public String getUnit() {
+        return unit;
+    }
+
+    public void setUnit(String unit) {
+        this.unit = unit;
+    }
+
+}

jackson/src/test/java/com/baeldung/jackson/dtos/withEnum/DistanceEnumWithValue.java

@@ -0,0 +1,29 @@
+package com.baeldung.jackson.dtos.withEnum;
+
+import com.fasterxml.jackson.annotation.JsonValue;
+
+public enum DistanceEnumWithValue {
+    KILOMETER("km", 1000), MILE("miles", 1609.34), METER("meters", 1), INCH("inches", 0.0254), CENTIMETER("cm", 0.01), MILLIMETER("mm", 0.001);
+
+    private String unit;
+    private final double meters;
+
+    private DistanceEnumWithValue(String unit, double meters) {
+        this.unit = unit;
+        this.meters = meters;
+    }
+
+    @JsonValue
+    public double getMeters() {
+        return meters;
+    }
+
+    public String getUnit() {
+        return unit;
+    }
+
+    public void setUnit(String unit) {
+        this.unit = unit;
+    }
+
+}

jackson/src/test/java/com/baeldung/jackson/dtos/withEnum/MyDtoWithEnumCustom.java

@@ -0,0 +1,59 @@
+package com.baeldung.jackson.dtos.withEnum;
+
+import com.baeldung.jackson.enums.Distance;
+
+public class MyDtoWithEnumCustom {
+
+    private String stringValue;
+    private int intValue;
+    private boolean booleanValue;
+    private Distance type;
+
+    public MyDtoWithEnumCustom() {
+        super();
+    }
+
+    public MyDtoWithEnumCustom(final String stringValue, final int intValue, final boolean booleanValue, final Distance type) {
+        super();
+
+        this.stringValue = stringValue;
+        this.intValue = intValue;
+        this.booleanValue = booleanValue;
+        this.type = type;
+    }
+
+    // API
+
+    public String getStringValue() {
+        return stringValue;
+    }
+
+    public void setStringValue(final String stringValue) {
+        this.stringValue = stringValue;
+    }
+
+    public int getIntValue() {
+        return intValue;
+    }
+
+    public void setIntValue(final int intValue) {
+        this.intValue = intValue;
+    }
+
+    public boolean isBooleanValue() {
+        return booleanValue;
+    }
+
+    public void setBooleanValue(final boolean booleanValue) {
+        this.booleanValue = booleanValue;
+    }
+
+    public Distance getType() {
+        return type;
+    }
+
+    public void setType(final Distance type) {
+        this.type = type;
+    }
+
+}

jackson/src/test/java/com/baeldung/jackson/dtos/withEnum/MyDtoWithEnumJsonFormat.java

@@ -0,0 +1,57 @@
+package com.baeldung.jackson.dtos.withEnum;
+
+public class MyDtoWithEnumJsonFormat {
+
+    private String stringValue;
+    private int intValue;
+    private boolean booleanValue;
+    private DistanceEnumWithJsonFormat distanceType;
+
+    public MyDtoWithEnumJsonFormat() {
+        super();
+    }
+
+    public MyDtoWithEnumJsonFormat(final String stringValue, final int intValue, final boolean booleanValue, final DistanceEnumWithJsonFormat type) {
+        super();
+
+        this.stringValue = stringValue;
+        this.intValue = intValue;
+        this.booleanValue = booleanValue;
+        this.distanceType = type;
+    }
+
+    // API
+
+    public String getStringValue() {
+        return stringValue;
+    }
+
+    public void setStringValue(final String stringValue) {
+        this.stringValue = stringValue;
+    }
+
+    public int getIntValue() {
+        return intValue;
+    }
+
+    public void setIntValue(final int intValue) {
+        this.intValue = intValue;
+    }
+
+    public boolean isBooleanValue() {
+        return booleanValue;
+    }
+
+    public void setBooleanValue(final boolean booleanValue) {
+        this.booleanValue = booleanValue;
+    }
+
+    public DistanceEnumWithJsonFormat getDistanceType() {
+        return distanceType;
+    }
+
+    public void setDistanceType(final DistanceEnumWithJsonFormat type) {
+        this.distanceType = type;
+    }
+
+}

jackson/src/test/java/com/baeldung/jackson/inheritance/ItemIdRemovedFromUserTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.jackson.inheritance;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.Test;
+
+import java.io.IOException;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class ItemIdRemovedFromUserTest {
+    @Test
+    public void givenRemoveItemJson_whenDeserialize_shouldHaveProperClassType() throws IOException {
+        //given
+        Event event = new ItemIdRemovedFromUser("1", 12345567L, "item_1", 2L);
+        ObjectMapper objectMapper = new ObjectMapper();
+        String eventJson = objectMapper.writeValueAsString(event);
+
+        //when
+        Event result = new ObjectMapper().readValue(eventJson, Event.class);
+
+        //then
+        assertTrue(result instanceof ItemIdRemovedFromUser);
+        assertEquals("item_1", ((ItemIdRemovedFromUser) result).getItemId());
+    }
+
+    @Test
+    public void givenAdddItemJson_whenSerialize_shouldIgnoreIdPropertyFromSuperclass() throws IOException {
+        //given
+        Event event = new ItemIdAddedToUser("1", 12345567L, "item_1", 2L);
+        ObjectMapper objectMapper = new ObjectMapper();
+
+        //when
+        String eventJson = objectMapper.writeValueAsString(event);
+
+        //then
+        assertFalse(eventJson.contains("id"));
+    }
+
+}

jackson/src/test/java/com/baeldung/jackson/test/JacksonAnnotationTest.java

@@ -1,6 +1,32 @@
 package com.baeldung.jackson.test;
 
-import com.baeldung.jackson.annotation.*;
+import static org.hamcrest.Matchers.containsString;
+import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.not;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+
+import java.io.IOException;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.TimeZone;
+
+import org.junit.Test;
+
+import com.baeldung.jackson.annotation.BeanWithCreator;
+import com.baeldung.jackson.annotation.BeanWithCustomAnnotation;
+import com.baeldung.jackson.annotation.BeanWithFilter;
+import com.baeldung.jackson.annotation.BeanWithGetter;
+import com.baeldung.jackson.annotation.BeanWithIgnore;
+import com.baeldung.jackson.annotation.BeanWithInject;
+import com.baeldung.jackson.annotation.ExtendableBean;
+import com.baeldung.jackson.annotation.MyBean;
+import com.baeldung.jackson.annotation.PrivateBean;
+import com.baeldung.jackson.annotation.RawBean;
+import com.baeldung.jackson.annotation.UnwrappedUser;
+import com.baeldung.jackson.annotation.UserWithIgnoreType;
+import com.baeldung.jackson.annotation.Zoo;
 import com.baeldung.jackson.bidirection.ItemWithIdentity;
 import com.baeldung.jackson.bidirection.ItemWithRef;
 import com.baeldung.jackson.bidirection.UserWithIdentity;
@@ -8,7 +34,7 @@ import com.baeldung.jackson.bidirection.UserWithRef;
 import com.baeldung.jackson.date.EventWithFormat;
 import com.baeldung.jackson.date.EventWithSerializer;
 import com.baeldung.jackson.dtos.MyMixInForIgnoreType;
-import com.baeldung.jackson.dtos.withEnum.TypeEnumWithValue;
+import com.baeldung.jackson.dtos.withEnum.DistanceEnumWithValue;
 import com.baeldung.jackson.exception.UserWithRoot;
 import com.baeldung.jackson.jsonview.Item;
 import com.baeldung.jackson.jsonview.Views;
@@ -20,17 +46,6 @@ import com.fasterxml.jackson.databind.SerializationFeature;
 import com.fasterxml.jackson.databind.ser.FilterProvider;
 import com.fasterxml.jackson.databind.ser.impl.SimpleBeanPropertyFilter;
 import com.fasterxml.jackson.databind.ser.impl.SimpleFilterProvider;
-import org.junit.Test;
-
-import java.io.IOException;
-import java.text.ParseException;
-import java.text.SimpleDateFormat;
-import java.util.Date;
-import java.util.TimeZone;
-
-import static org.hamcrest.Matchers.*;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertThat;
 
 public class JacksonAnnotationTest {
 
@@ -85,10 +100,10 @@ public class JacksonAnnotationTest {
     }
 
     @Test
-    public void whenSerializingUsingJsonValue_thenCorrect() throws JsonProcessingException {
+    public void whenSerializingUsingJsonValue_thenCorrect() throws IOException {
-        final String enumAsString = new ObjectMapper().writeValueAsString(TypeEnumWithValue.TYPE1);
+        final String enumAsString = new ObjectMapper().writeValueAsString(DistanceEnumWithValue.MILE);
 
-        assertThat(enumAsString, is("\"Type A\""));
+        assertThat(enumAsString, is("1609.34"));
     }
 
     @Test

jackson/src/test/java/com/baeldung/jackson/test/JacksonSerializationEnumsUnitTest.java

@@ -6,14 +6,14 @@ import static org.junit.Assert.assertThat;
 
 import java.io.IOException;
 
-import com.baeldung.jackson.dtos.withEnum.MyDtoWithEnum;
-import com.baeldung.jackson.dtos.withEnum.TypeEnum;
-import com.baeldung.jackson.dtos.withEnum.TypeEnumSimple;
-import com.baeldung.jackson.dtos.withEnum.TypeEnumWithValue;
-import com.baeldung.jackson.dtos.withEnum.MyDtoWithEnumCustom;
-import com.baeldung.jackson.dtos.withEnum.TypeEnumWithCustomSerializer;
 import org.junit.Test;
 
+import com.baeldung.jackson.dtos.withEnum.DistanceEnumSimple;
+import com.baeldung.jackson.dtos.withEnum.DistanceEnumWithJsonFormat;
+import com.baeldung.jackson.dtos.withEnum.DistanceEnumWithValue;
+import com.baeldung.jackson.dtos.withEnum.MyDtoWithEnumCustom;
+import com.baeldung.jackson.dtos.withEnum.MyDtoWithEnumJsonFormat;
+import com.baeldung.jackson.enums.Distance;
 import com.fasterxml.jackson.core.JsonParseException;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
@@ -24,10 +24,9 @@ public class JacksonSerializationEnumsUnitTest {
     @Test
     public final void whenSerializingASimpleEnum_thenCorrect() throws JsonParseException, IOException {
         final ObjectMapper mapper = new ObjectMapper();
-        final String enumAsString = mapper.writeValueAsString(TypeEnumSimple.TYPE1);
+        final String enumAsString = mapper.writeValueAsString(DistanceEnumSimple.MILE);
-        System.out.println(enumAsString);
 
-        assertThat(enumAsString, containsString("TYPE1"));
+        assertThat(enumAsString, containsString("MILE"));
     }
 
     // tests - enum with main value
@@ -35,10 +34,9 @@ public class JacksonSerializationEnumsUnitTest {
     @Test
     public final void whenSerializingAEnumWithValue_thenCorrect() throws JsonParseException, IOException {
         final ObjectMapper mapper = new ObjectMapper();
-        final String enumAsString = mapper.writeValueAsString(TypeEnumWithValue.TYPE1);
+        final String enumAsString = mapper.writeValueAsString(DistanceEnumWithValue.MILE);
-        System.out.println(enumAsString);
 
-        assertThat(enumAsString, is("\"Type A\""));
+        assertThat(enumAsString, is("1609.34"));
     }
 
     // tests - enum
@@ -46,28 +44,25 @@ public class JacksonSerializationEnumsUnitTest {
     @Test
     public final void whenSerializingAnEnum_thenCorrect() throws JsonParseException, IOException {
         final ObjectMapper mapper = new ObjectMapper();
-        final String enumAsString = mapper.writeValueAsString(TypeEnum.TYPE1);
+        final String enumAsString = mapper.writeValueAsString(DistanceEnumWithJsonFormat.MILE);
 
-        System.out.println(enumAsString);
+        assertThat(enumAsString, containsString("\"meters\":1609.34"));
-        assertThat(enumAsString, containsString("\"name\":\"Type A\""));
     }
 
     @Test
     public final void whenSerializingEntityWithEnum_thenCorrect() throws JsonParseException, IOException {
         final ObjectMapper mapper = new ObjectMapper();
-        final String enumAsString = mapper.writeValueAsString(new MyDtoWithEnum("a", 1, true, TypeEnum.TYPE1));
+        final String enumAsString = mapper.writeValueAsString(new MyDtoWithEnumJsonFormat("a", 1, true, DistanceEnumWithJsonFormat.MILE));
 
-        System.out.println(enumAsString);
+        assertThat(enumAsString, containsString("\"meters\":1609.34"));
-        assertThat(enumAsString, containsString("\"name\":\"Type A\""));
     }
 
     @Test
     public final void whenSerializingArrayOfEnums_thenCorrect() throws JsonParseException, IOException {
         final ObjectMapper mapper = new ObjectMapper();
-        final String json = mapper.writeValueAsString(new TypeEnum[] { TypeEnum.TYPE1, TypeEnum.TYPE2 });
+        final String json = mapper.writeValueAsString(new DistanceEnumWithJsonFormat[] { DistanceEnumWithJsonFormat.MILE, DistanceEnumWithJsonFormat.KILOMETER });
 
-        System.out.println(json);
+        assertThat(json, containsString("\"meters\":1609.34"));
-        assertThat(json, containsString("\"name\":\"Type A\""));
     }
 
     // tests - enum with custom serializer
@@ -75,10 +70,9 @@ public class JacksonSerializationEnumsUnitTest {
     @Test
     public final void givenCustomSerializer_whenSerializingEntityWithEnum_thenCorrect() throws JsonParseException, IOException {
         final ObjectMapper mapper = new ObjectMapper();
-        final String enumAsString = mapper.writeValueAsString(new MyDtoWithEnumCustom("a", 1, true, TypeEnumWithCustomSerializer.TYPE1));
+        final String enumAsString = mapper.writeValueAsString(new MyDtoWithEnumCustom("a", 1, true, Distance.MILE));
 
-        System.out.println(enumAsString);
+        assertThat(enumAsString, containsString("\"meters\":1609.34"));
-        assertThat(enumAsString, containsString("\"name\":\"Type A\""));
     }
 
 }

java-mongodb/.gitignore

@@ -0,0 +1,5 @@
+.classpath
+.project
+.settings
+target
+build

java-mongodb/pom.xml

@@ -0,0 +1,98 @@
+<?xml version="1.0"?>
+<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.baeldung</groupId>
+    <artifactId>java-mongodb</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <dependencies>
+
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>de.flapdoodle.embedmongo</groupId>
+            <artifactId>de.flapdoodle.embedmongo</artifactId>
+            <version>${flapdoodle.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+
+        <dependency>
+            <groupId>org.mongodb</groupId>
+            <artifactId>mongo-java-driver</artifactId>
+            <version>${mongo.version}</version>
+        </dependency>
+
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>${maven-surefire-plugin.version}</version>
+                <configuration>
+                    <excludes>
+                        <exclude>**/*IntegrationTest.java</exclude>
+                        <exclude>**/*LongRunningUnitTest.java</exclude>
+                        <exclude>**/*ManualTest.java</exclude>
+                    </excludes>
+                    <testFailureIgnore>true</testFailureIgnore>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <profiles>
+        <profile>
+            <id>integration</id>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-surefire-plugin</artifactId>
+                        <executions>
+                            <execution>
+                                <phase>integration-test</phase>
+                                <goals>
+                                    <goal>test</goal>
+                                </goals>
+                                <configuration>
+                                    <excludes>
+                                        <exclude>**/*ManualTest.java</exclude>
+                                    </excludes>
+                                    <includes>
+                                        <include>**/*IntegrationTest.java</include>
+                                    </includes>
+                                </configuration>
+                            </execution>
+                        </executions>
+                        <configuration>
+                            <systemPropertyVariables>
+                                <test.mime>json</test.mime>
+                            </systemPropertyVariables>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+    </profiles>
+
+    <properties>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+        <junit.version>4.12</junit.version>
+        <mongo.version>3.4.1</mongo.version>
+        <flapdoodle.version>1.11</flapdoodle.version>
+
+        <maven-surefire-plugin.version>2.19.1</maven-surefire-plugin.version>
+    </properties>
+
+</project>

java-mongodb/src/main/java/com/baeldung/MongoExample.java

@@ -0,0 +1,53 @@
+package com.baeldung;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DB;
+import com.mongodb.DBCollection;
+import com.mongodb.DBCursor;
+import com.mongodb.MongoClient;
+
+public class MongoExample {
+    public static void main(String[] args) {
+
+        MongoClient mongoClient = new MongoClient("localhost", 27017);
+
+        DB database = mongoClient.getDB("myMongoDb");
+
+        // print existing databases
+        mongoClient.getDatabaseNames().forEach(System.out::println);
+
+        database.createCollection("customers", null);
+
+        // print all collections in customers database
+        database.getCollectionNames().forEach(System.out::println);
+
+        // create data
+        DBCollection collection = database.getCollection("customers");
+        BasicDBObject document = new BasicDBObject();
+        document.put("name", "Shubham");
+        document.put("company", "Baeldung");
+        collection.insert(document);
+
+        // update data
+        BasicDBObject query = new BasicDBObject();
+        query.put("name", "Shubham");
+        BasicDBObject newDocument = new BasicDBObject();
+        newDocument.put("name", "John");
+        BasicDBObject updateObject = new BasicDBObject();
+        updateObject.put("$set", newDocument);
+        collection.update(query, updateObject);
+
+        // read data
+        BasicDBObject searchQuery = new BasicDBObject();
+        searchQuery.put("name", "John");
+        DBCursor cursor = collection.find(searchQuery);
+        while (cursor.hasNext()) {
+            System.out.println(cursor.next());
+        }
+
+        // delete data
+        BasicDBObject deleteQuery = new BasicDBObject();
+        deleteQuery.put("name", "John");
+        collection.remove(deleteQuery);
+    }
+}

java-mongodb/src/test/java/com/baeldung/AppIntegrationTest.java

@@ -0,0 +1,72 @@
+package com.baeldung;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.DB;
+import com.mongodb.DBCollection;
+import com.mongodb.DBCursor;
+import com.mongodb.Mongo;
+
+import de.flapdoodle.embedmongo.MongoDBRuntime;
+import de.flapdoodle.embedmongo.MongodExecutable;
+import de.flapdoodle.embedmongo.MongodProcess;
+import de.flapdoodle.embedmongo.config.MongodConfig;
+import de.flapdoodle.embedmongo.distribution.Version;
+import de.flapdoodle.embedmongo.runtime.Network;
+
+public class AppIntegrationTest {
+
+    private static final String DB_NAME = "myMongoDb";
+    private MongodExecutable mongodExe;
+    private MongodProcess mongod;
+    private Mongo mongo;
+    private DB db;
+    private DBCollection collection;
+
+    @Before
+    public void setup() throws Exception {
+        // Creating Mongodbruntime instance
+        MongoDBRuntime runtime = MongoDBRuntime.getDefaultInstance();
+
+        // Creating MongodbExecutable
+        mongodExe = runtime.prepare(new MongodConfig(Version.V2_0_1, 12345, Network.localhostIsIPv6()));
+
+        // Starting Mongodb
+        mongod = mongodExe.start();
+        mongo = new Mongo("localhost", 12345);
+
+        // Creating DB
+        db = mongo.getDB(DB_NAME);
+
+        // Creating collection Object and adding values
+        collection = db.getCollection("customers");
+    }
+
+    @After
+    public void teardown() throws Exception {
+        mongod.stop();
+        mongodExe.cleanup();
+    }
+
+    @Test
+    public void testAddressPersistance() {
+        BasicDBObject contact = new BasicDBObject();
+        contact.put("name", "John");
+        contact.put("company", "Baeldung");
+
+        // Inserting document
+        collection.insert(contact);
+        DBCursor cursorDoc = collection.find();
+        BasicDBObject contact1 = new BasicDBObject();
+        while (cursorDoc.hasNext()) {
+            contact1 = (BasicDBObject) cursorDoc.next();
+            System.out.println(contact1);
+        }
+        assertEquals(contact1.get("name"), "John");
+    }
+}

javax-servlets/README.md

@@ -0,0 +1,2 @@
+### Relevant Articles:
+- [Introduction to Java Servlets](http://www.baeldung.com/intro-to-servlets)

jee7/pom.xml

@@ -10,7 +10,7 @@
     <packaging>war</packaging>
 
     <properties>
-        <java.min.version>1.7</java.min.version>
+        <java.min.version>1.8</java.min.version>
         <maven.min.version>3.0.0</maven.min.version>
 
         <junit.version>4.12</junit.version>

jee7/src/main/java/com/baeldung/json/Person.java

@@ -0,0 +1,43 @@
+package com.baeldung.json;
+
+import java.util.Date;
+import java.util.List;
+
+public class Person {
+    private String firstName;
+    private String lastName;
+    private Date birthdate;
+    private List<String> emails;
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+
+    public Date getBirthdate() {
+        return birthdate;
+    }
+
+    public void setBirthdate(Date birthdate) {
+        this.birthdate = birthdate;
+    }
+
+    public List<String> getEmails() {
+        return emails;
+    }
+
+    public void setEmails(List<String> emails) {
+        this.emails = emails;
+    }
+}

jee7/src/main/java/com/baeldung/json/PersonBuilder.java

@@ -0,0 +1,42 @@
+package com.baeldung.json;
+
+import javax.json.*;
+import java.io.IOException;
+import java.io.StringReader;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class PersonBuilder {
+    private String jsonString;
+
+    private SimpleDateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy");
+
+    public PersonBuilder(String jsonString) {
+        this.jsonString = jsonString;
+    }
+
+    public Person build() throws IOException, ParseException {
+        JsonReader reader = Json.createReader(new StringReader(jsonString));
+
+        JsonObject jsonObject = reader.readObject();
+
+        Person person = new Person();
+
+        person.setFirstName(jsonObject.getString("firstName"));
+        person.setLastName(jsonObject.getString("lastName"));
+        person.setBirthdate(dateFormat.parse(jsonObject.getString("birthdate")));
+
+        JsonArray emailsJson = jsonObject.getJsonArray("emails");
+
+        List<String> emails = emailsJson.getValuesAs(JsonString.class).stream()
+          .map(JsonString::getString)
+          .collect(Collectors.toList());
+
+        person.setEmails(emails);
+
+        return person;
+    }
+
+}

jee7/src/main/java/com/baeldung/json/PersonWriter.java

@@ -0,0 +1,60 @@
+package com.baeldung.json;
+
+import javax.json.*;
+import javax.json.stream.JsonGenerator;
+import java.io.IOException;
+import java.io.StringWriter;
+import java.io.Writer;
+import java.text.SimpleDateFormat;
+import java.util.HashMap;
+import java.util.Map;
+
+public class PersonWriter {
+    private Person person;
+
+    private SimpleDateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy");
+
+    public PersonWriter(Person person) {
+        this.person = person;
+    }
+
+    public String write() throws IOException {
+        JsonObjectBuilder objectBuilder = Json
+          .createObjectBuilder()
+          .add("firstName", person.getFirstName())
+          .add("lastName", person.getLastName())
+          .add("birthdate", dateFormat.format(person.getBirthdate()));
+
+        final JsonArrayBuilder arrayBuilder = Json.createArrayBuilder();
+
+        person.getEmails().forEach(arrayBuilder::add);
+
+        objectBuilder.add("emails", arrayBuilder);
+
+        JsonObject jsonObject = objectBuilder.build();
+
+        JsonWriterFactory writerFactory = createWriterFactory();
+
+        return writeToString(jsonObject, writerFactory);
+
+    }
+
+    private String writeToString(JsonObject jsonObject, JsonWriterFactory writerFactory) throws IOException {
+        String jsonString;
+        try (Writer writer = new StringWriter()) {
+            writerFactory
+              .createWriter(writer)
+              .write(jsonObject);
+            jsonString = writer.toString();
+        }
+        return jsonString;
+    }
+
+    private JsonWriterFactory createWriterFactory() {
+        Map<String, Boolean> config = new HashMap<>();
+
+        config.put(JsonGenerator.PRETTY_PRINTING, true);
+
+        return Json.createWriterFactory(config);
+    }
+}

jee7/src/test/java/com/baeldug/json/JsonUnitTest.java

@@ -0,0 +1,135 @@
+package com.baeldug.json;
+
+import static org.hamcrest.CoreMatchers.hasItems;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+
+import java.io.IOException;
+import java.io.StringReader;
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.Arrays;
+
+import javax.json.Json;
+import javax.json.JsonObject;
+import javax.json.JsonReader;
+import javax.json.stream.JsonParser;
+import javax.json.stream.JsonParser.Event;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import com.baeldung.json.Person;
+import com.baeldung.json.PersonBuilder;
+import com.baeldung.json.PersonWriter;
+
+public class JsonUnitTest {
+    private Person person;
+
+    private SimpleDateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy");
+    private String personJson; 
+    private String petshopJson; 
+    
+    @Test
+    public void whenPersonIsConvertedToString_thenAValidJsonStringIsReturned() throws IOException {
+        String generatedJsonString = new PersonWriter(person).write();
+        
+        assertEquals(
+                "Generated String has the expected format and content", 
+                personJson, 
+                generatedJsonString);
+    }
+    
+    @Test
+    public void whenJsonStringIsConvertedToPerson_thenAValidObjectIsReturned(
+            ) throws IOException, ParseException {        
+        Person person = new PersonBuilder(personJson).build();
+        
+        assertEquals("First name has expected value", "Michael", person.getFirstName());
+        assertEquals("Last name has expected value", "Scott", person.getLastName());
+        assertEquals(
+                "Birthdate has expected value", 
+                dateFormat.parse("06/15/1978"), 
+                person.getBirthdate());
+        assertThat(
+                "Email list has two items", 
+                person.getEmails(), 
+                hasItems("michael.scott@dd.com", "michael.scarn@gmail.com"));
+    }
+
+    @Test
+    public void whenUsingObjectModelToQueryForSpecificProperty_thenExpectedValueIsReturned(
+            ) throws IOException, ParseException {
+        JsonReader reader = Json.createReader(new StringReader(petshopJson));
+
+        JsonObject jsonObject = reader.readObject();
+        
+        assertEquals(
+                "The query should return the 'name' property of the third pet from the list", 
+                "Jake", 
+                jsonObject.getJsonArray("pets").getJsonObject(2).getString("name"));
+    }
+    
+    @Test
+    public void whenUsingStreamingApiToQueryForSpecificProperty_thenExpectedValueIsReturned(
+            ) throws IOException, ParseException {
+        JsonParser jsonParser = Json.createParser(new StringReader(petshopJson));
+        
+        int count = 0;
+        String result = null;
+        
+        while(jsonParser.hasNext()) {
+            Event e = jsonParser.next();
+            
+            if (e == Event.KEY_NAME) {
+                if(jsonParser.getString().equals("name")) {
+                   jsonParser.next();
+                   
+                   if(++count == 3) {
+                       result = jsonParser.getString();
+                       break;
+                   }
+                }   
+            }
+        }
+        
+        assertEquals(
+                "The query should return the 'name' property of the third pet from the list", 
+                "Jake", 
+                result);
+    }    
+    
+    @Before
+    public void init() throws ParseException {
+        // Creates a Person object
+        person = new Person();
+
+        person.setFirstName("Michael");
+        person.setLastName("Scott");
+        person.setBirthdate(dateFormat.parse("06/15/1978"));
+        person.setEmails(Arrays.asList("michael.scott@dd.com", "michael.scarn@gmail.com"));
+
+        // Initializes the Person Json
+        personJson = "\n" +
+                "{\n" +
+                "    \"firstName\":\"Michael\",\n" +
+                "    \"lastName\":\"Scott\",\n" +
+                "    \"birthdate\":\"06/15/1978\",\n" +
+                "    \"emails\":[\n" +
+                "        \"michael.scott@dd.com\",\n" +
+                "        \"michael.scarn@gmail.com\"\n" +
+                "    ]\n" +
+                "}";
+        
+        // Initializes the Pet Shop Json
+        petshopJson = "\n" +
+        "{\n" +
+        "    \"ownerId\":\"1\", \n" +
+        "    \"pets\":[ \n" +
+        "        {\"name\": \"Kitty\", \"type\": \"cat\"}, \n" +
+        "        {\"name\": \"Rex\", \"type\": \"dog\"}, \n" +
+        "        {\"name\": \"Jake\", \"type\": \"dog\"} \n" +
+        "    ]\n" +
+        "}";
+    }
+}

jsoup/README.md

@@ -0,0 +1,10 @@
+=========
+
+## jsoup Example Project
+
+### Relevant Articles: 
+- [Parsing HTML in Java with Jsoup](http://www.baeldung.com/java-with-jsoup)
+
+### Build the Project
+
+mvn clean install

jsoup/pom.xml

@@ -15,15 +15,16 @@
             <version>${jsoup.version}</version>
         </dependency>
         <dependency>
-            <groupId>commons-io</groupId>
+            <groupId>junit</groupId>
-            <artifactId>commons-io</artifactId>
+            <artifactId>junit</artifactId>
-            <version>${commons.io.version}</version>
+            <version>4.12</version>
+            <scope>test</scope>
         </dependency>
     </dependencies>
     <properties>
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
-        <commons.io.version>2.5</commons.io.version>
+
-        <jsoup.version>1.10.1</jsoup.version>
+        <jsoup.version>1.10.2</jsoup.version>
     </properties>
 </project>

jsoup/src/test/java/com/baeldung/jsoup/JsoupParserTest.java

@@ -1,47 +1,52 @@
 package com.baeldung.jsoup;
 
-import java.io.File;
-import java.io.IOException;
-import org.apache.commons.io.FileUtils;
 import org.jsoup.HttpStatusException;
 import org.jsoup.Jsoup;
 import org.jsoup.nodes.Document;
 import org.jsoup.nodes.Element;
 import org.jsoup.parser.Tag;
 import org.jsoup.select.Elements;
+import org.junit.Before;
+import org.junit.Test;
 
-public class JsoupExample {
+import java.io.IOException;
 
-    public static void main(String[] args) throws IOException {
+import static org.junit.Assert.assertEquals;
-        scrapeSpringBlog();
+import static org.junit.Assert.assertTrue;
+
+public class JsoupParserTest {
+
+    Document doc;
+
+    @Before
+    public void setUp() throws IOException {
+        doc = Jsoup.connect("https://spring.io/blog").get();
     }
 
-    static void scrapeSpringBlog() throws IOException {
+    @Test
-        String blogUrl = "https://spring.io/blog";
+    public void loadDocument404() throws IOException {
-        Document doc = Jsoup.connect(blogUrl).get();
-
         try {
-            Document doc404 = Jsoup.connect("https://spring.io/will-not-be-found").get();
+            doc = Jsoup.connect("https://spring.io/will-not-be-found").get();
         } catch (HttpStatusException ex) {
-            System.out.println(ex.getMessage());
+            assertEquals(404, ex.getStatusCode());
+        }
     }
 
-        Document docCustomConn = Jsoup.connect(blogUrl).userAgent("Mozilla").get();
+    @Test
-        docCustomConn = Jsoup.connect(blogUrl).timeout(5000).get();
+    public void loadDocumentCustomized() throws IOException {
-        docCustomConn = Jsoup.connect(blogUrl).cookie("cookiename", "val234").get();
+        doc = Jsoup.connect("https://spring.io/blog")
-        // docCustomConn = Jsoup.connect(blogUrl).data("datakey", "datavalue").post();
-        docCustomConn = Jsoup.connect(blogUrl).header("headersecurity", "xyz123").get();
-
-        docCustomConn = Jsoup.connect(blogUrl)
                 .userAgent("Mozilla")
                 .timeout(5000)
                 .cookie("cookiename", "val234")
                 .cookie("anothercookie", "ilovejsoup")
+                .referrer("http://google.com")
                 .header("headersecurity", "xyz123")
                 .get();
+    }
 
+    @Test
+    public void examplesSelectors() {
         Elements links = doc.select("a");
-        Elements sections = doc.select("section");
         Elements logo = doc.select(".spring-logo--container");
         Elements pagination = doc.select("#pagination_control");
         Elements divsDescendant = doc.select("header div");
@@ -50,6 +55,15 @@ public class JsoupExample {
         Element pag = doc.getElementById("pagination_control");
         Elements desktopOnly = doc.getElementsByClass("desktopOnly");
 
+        Elements sections = doc.select("section");
+        Element firstSection = sections.first();
+        Elements sectionParagraphs = firstSection.select(".paragraph");
+    }
+
+    @Test
+    public void examplesTraversing() {
+        Elements sections = doc.select("section");
+
         Element firstSection = sections.first();
         Element lastSection = sections.last();
         Element secondSection = sections.get(2);
@@ -58,10 +72,11 @@ public class JsoupExample {
         Elements children = firstSection.children();
         Elements siblings = firstSection.siblingElements();
 
-        sections.stream().forEach(el -> System.out.println("section: " + el));
+        sections.forEach(el -> System.out.println("section: " + el));
-
+    }
-        Elements sectionParagraphs = firstSection.select(".paragraph");
 
+    @Test
+    public void examplesExtracting() {
         Element firstArticle = doc.select("article").first();
         Element timeElement = firstArticle.select("time").first();
         String dateTimeOfFirstArticle = timeElement.attr("datetime");
@@ -69,7 +84,15 @@ public class JsoupExample {
         String sectionDivText = sectionDiv.text();
         String articleHtml = firstArticle.html();
         String outerHtml = firstArticle.outerHtml();
+    }
 
+    @Test
+    public void examplesModifying() {
+        Element firstArticle = doc.select("article").first();
+        Element timeElement = firstArticle.select("time").first();
+        Element sectionDiv = firstArticle.select("section div").first();
+
+        String dateTimeOfFirstArticle = timeElement.attr("datetime");
         timeElement.attr("datetime", "2016-12-16 15:19:54.3");
         sectionDiv.text("foo bar");
         firstArticle.select("h2").html("<div><span></span></div>");
@@ -83,7 +106,6 @@ public class JsoupExample {
         doc.select("li.navbar-link").remove();
         firstArticle.select("img").remove();
 
-        File indexFile = new File("/tmp", "spring_blog_home.html");
+        assertTrue(doc.html().contains("http://baeldung.com"));
-        FileUtils.writeStringToFile(indexFile, doc.html(), doc.charset());
     }
 }

kotlin/pom.xml

@@ -0,0 +1,65 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.baeldung</groupId>
+    <artifactId>kotlin</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib</artifactId>
+            <version>${kotlin-stdlib.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-test-junit</artifactId>
+            <version>${kotlin-test-junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
+        <testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>
+        <plugins>
+            <plugin>
+                <artifactId>kotlin-maven-plugin</artifactId>
+                <groupId>org.jetbrains.kotlin</groupId>
+                <version>${kotlin-maven-plugin.version}</version>
+                <executions>
+                    <execution>
+                        <id>compile</id>
+                        <goals>
+                            <goal>compile</goal>
+                        </goals>
+                    </execution>
+
+                    <execution>
+                        <id>test-compile</id>
+                        <goals>
+                            <goal>test-compile</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <junit.version>4.12</junit.version>
+        <kotlin-test-junit.version>1.0.4</kotlin-test-junit.version>
+        <kotlin-stdlib.version>1.0.4</kotlin-stdlib.version>
+        <kotlin-maven-plugin.version>1.0.4</kotlin-maven-plugin.version>
+    </properties>
+
+</project>

kotlin/src/main/kotlin/com/baeldung/kotlin/Example1.kt

@@ -0,0 +1,5 @@
+package com.baeldung.kotlin
+
+fun main(args: Array<String>){
+    println("hello word")
+}

kotlin/src/main/kotlin/com/baeldung/kotlin/Item.kt

@@ -0,0 +1,14 @@
+package com.baeldung.kotlin
+
+open class Item(val id: String, val name: String = "unknown_name") {
+    open fun getIdOfItem(): String {
+        return id
+    }
+}
+
+class ItemWithCategory(id: String, name: String, val categoryId: String) : Item(id, name) {
+    override fun getIdOfItem(): String {
+        return id + name
+    }
+}
+

kotlin/src/main/kotlin/com/baeldung/kotlin/ItemService.kt

@@ -0,0 +1,66 @@
+package com.baeldung.kotlin
+
+import java.util.*
+
+class ItemService {
+    fun findItemNameForId(id: String): Item? {
+        val itemId = UUID.randomUUID().toString()
+        return Item(itemId, "name-$itemId")
+    }
+}
+
+class ItemManager(val categoryId: String, val dbConnection: String) {
+    var email = ""
+
+    constructor(categoryId: String, dbConnection: String, email: String)
+    : this(categoryId, dbConnection) {
+        this.email = email
+    }
+
+    fun isFromSpecificCategory(catId: String): Boolean {
+        return categoryId == catId
+    }
+
+    fun makeAnalyisOfCategory(catId: String): Unit {
+        val result = if (catId == "100") "Yes" else "No"
+        println(result)
+
+    }
+}
+
+fun main(args: Array<String>) {
+    val numbers = arrayOf("first", "second", "third", "fourth")
+
+    var concat = ""
+    for (n in numbers) {
+        concat += n
+    }
+
+    var sum = 0
+    for (i in 2..9) {
+        sum += i
+    }
+
+    val firstName = "Tom"
+    val secondName = "Mary"
+    val concatOfNames = "$firstName + $secondName"
+    println("Names: $concatOfNames")
+
+    val itemManager = ItemManager("cat_id", "db://connection")
+    val result = "function result: ${itemManager.isFromSpecificCategory("1")}"
+    println(result)
+
+    val number = 2
+    if (number < 10) {
+        println("number less that 10")
+    } else if (number > 10) {
+        println("number is greater that 10")
+    }
+
+    val name = "John"
+    when (name) {
+        "John" -> println("Hi man")
+        "Alice" -> println("Hi lady")
+    }
+
+}

kotlin/src/main/kotlin/com/baeldung/kotlin/ListExtension.kt

@@ -0,0 +1,14 @@
+package com.baeldung.kotlin
+
+import java.util.concurrent.ThreadLocalRandom
+
+class ListExtension {
+    fun <T> List<T>.random(): T? {
+        if (this.isEmpty()) return null
+        return get(ThreadLocalRandom.current().nextInt(count()))
+    }
+
+    fun <T> getRandomElementOfList(list: List<T>): T? {
+        return list.random()
+    }
+}

kotlin/src/test/kotlin/com/baeldung/kotlin/ItemServiceTest.kt

@@ -0,0 +1,20 @@
+package com.baeldung.kotlin
+
+import org.junit.Test
+import kotlin.test.assertNotNull
+
+class ItemServiceTest {
+    @Test
+    fun givenItemId_whenGetForOptionalItem_shouldMakeActionOnNonNullValue() {
+        //given
+        val id = "item_id"
+        val itemService = ItemService()
+
+        //when
+        val result = itemService.findItemNameForId(id)
+
+        //then
+        assertNotNull(result?.let { it -> it.id })
+        assertNotNull(result!!.id)
+    }
+}

kotlin/src/test/kotlin/com/baeldung/kotlin/ListExtensionTest.kt

@@ -0,0 +1,19 @@
+package com.baeldung.kotlin
+
+import com.baeldung.kotlin.ListExtension
+import org.junit.Test
+import kotlin.test.assertTrue
+
+class ListExtensionTest {
+    @Test
+    fun givenList_whenExecuteExtensionFunctionOnList_shouldReturnRandomElementOfList(){
+        //given
+        val elements = listOf("a", "b", "c")
+
+        //when
+        val result = ListExtension().getRandomElementOfList(elements)
+
+        //then
+        assertTrue(elements.contains(result))
+    }
+}

metrics/pom.xml

@@ -0,0 +1,75 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <artifactId>parent-modules</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>metrics</artifactId>
+
+
+    <properties>
+        <dep.ver.metrics>3.1.2</dep.ver.metrics>
+        <dep.ver.servlet>3.1.0</dep.ver.servlet>
+        <dep.ver.junit>4.12</dep.ver.junit>
+
+        <maven.compiler-plugin.version>3.6.0</maven.compiler-plugin.version>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.dropwizard.metrics</groupId>
+            <artifactId>metrics-core</artifactId>
+            <version>${dep.ver.metrics}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.dropwizard.metrics</groupId>
+            <artifactId>metrics-healthchecks</artifactId>
+            <version>${dep.ver.metrics}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.dropwizard.metrics</groupId>
+            <artifactId>metrics-servlets</artifactId>
+            <version>${dep.ver.metrics}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.dropwizard.metrics</groupId>
+            <artifactId>metrics-servlet</artifactId>
+            <version>${dep.ver.metrics}</version>
+        </dependency>
+        <dependency>
+            <groupId>javax.servlet</groupId>
+            <artifactId>javax.servlet-api</artifactId>
+            <version>${dep.ver.servlet}</version>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${dep.ver.junit}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven.compiler-plugin.version}</version>
+                <configuration>
+                    <source>${maven.compiler.source}</source>
+                    <target>${maven.compiler.target}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

metrics/src/main/java/com/baeldung/metrics/core/ActiveUserCountGauge.java

@@ -0,0 +1,17 @@
+package com.baeldung.metrics.core;
+
+import java.util.List;
+
+import com.codahale.metrics.DerivativeGauge;
+import com.codahale.metrics.Gauge;
+
+public class ActiveUserCountGauge extends DerivativeGauge<List<Long>, Integer> {
+    public ActiveUserCountGauge(Gauge<List<Long>> base) {
+        super(base);
+    }
+
+    @Override
+    protected Integer transform(List<Long> value) {
+        return value.size();
+    }
+}

metrics/src/main/java/com/baeldung/metrics/core/ActiveUsersGauge.java

@@ -0,0 +1,25 @@
+package com.baeldung.metrics.core;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+import com.codahale.metrics.CachedGauge;
+
+public class ActiveUsersGauge extends CachedGauge<List<Long>> {
+    public ActiveUsersGauge(long timeout, TimeUnit timeoutUnit) {
+        super(timeout, timeoutUnit);
+    }
+
+    @Override
+    protected List<Long> loadValue() {
+        return getActiveUserCount();
+    }
+
+    private List<Long> getActiveUserCount() {
+        // mock reading from database and count the active users, return a fixed value
+        List<Long> result = new ArrayList<Long>();
+        result.add(12L);
+        return result;
+    }
+}

metrics/src/main/java/com/baeldung/metrics/core/AttendanceRatioGauge.java

@@ -0,0 +1,18 @@
+package com.baeldung.metrics.core;
+
+import com.codahale.metrics.RatioGauge;
+
+public class AttendanceRatioGauge extends RatioGauge {
+    private int attendanceCount;
+    private int courseCount;
+
+    public AttendanceRatioGauge(int attendanceCount, int courseCount) {
+        this.attendanceCount = attendanceCount;
+        this.courseCount = courseCount;
+    }
+
+    @Override
+    protected Ratio getRatio() {
+        return Ratio.of(attendanceCount, courseCount);
+    }
+}

metrics/src/main/java/com/baeldung/metrics/healthchecks/DatabaseHealthCheck.java

@@ -0,0 +1,10 @@
+package com.baeldung.metrics.healthchecks;
+
+import com.codahale.metrics.health.HealthCheck;
+
+public class DatabaseHealthCheck extends HealthCheck {
+    @Override
+    protected Result check() throws Exception {
+        return Result.healthy();
+    }
+}

metrics/src/main/java/com/baeldung/metrics/healthchecks/UserCenterHealthCheck.java

@@ -0,0 +1,10 @@
+package com.baeldung.metrics.healthchecks;
+
+import com.codahale.metrics.health.HealthCheck;
+
+public class UserCenterHealthCheck extends HealthCheck {
+    @Override
+    protected Result check() throws Exception {
+        return Result.healthy();
+    }
+}

metrics/src/main/java/com/baeldung/metrics/servlet/MyInstrumentedFilterContextListener.java

@@ -0,0 +1,13 @@
+package com.baeldung.metrics.servlet;
+
+import com.codahale.metrics.MetricRegistry;
+import com.codahale.metrics.servlet.InstrumentedFilterContextListener;
+
+public class MyInstrumentedFilterContextListener extends InstrumentedFilterContextListener {
+    public static final MetricRegistry REGISTRY = new MetricRegistry();
+
+    @Override
+    protected MetricRegistry getMetricRegistry() {
+        return REGISTRY;
+    }
+}

metrics/src/main/java/com/baeldung/metrics/servlets/MyHealthCheckServletContextListener.java

@@ -0,0 +1,18 @@
+package com.baeldung.metrics.servlets;
+
+import com.baeldung.metrics.healthchecks.DatabaseHealthCheck;
+import com.codahale.metrics.health.HealthCheckRegistry;
+import com.codahale.metrics.servlets.HealthCheckServlet;
+
+public class MyHealthCheckServletContextListener extends HealthCheckServlet.ContextListener {
+    public static final HealthCheckRegistry HEALTH_CHECK_REGISTRY = new HealthCheckRegistry();
+
+    static {
+        HEALTH_CHECK_REGISTRY.register("db", new DatabaseHealthCheck());
+    }
+
+    @Override
+    protected HealthCheckRegistry getHealthCheckRegistry() {
+        return HEALTH_CHECK_REGISTRY;
+    }
+}

metrics/src/main/java/com/baeldung/metrics/servlets/MyMetricsServletContextListener.java

@@ -0,0 +1,25 @@
+package com.baeldung.metrics.servlets;
+
+import com.codahale.metrics.Counter;
+import com.codahale.metrics.Histogram;
+import com.codahale.metrics.MetricRegistry;
+import com.codahale.metrics.servlets.MetricsServlet;
+
+public class MyMetricsServletContextListener extends MetricsServlet.ContextListener {
+    private static final MetricRegistry METRIC_REGISTRY = new MetricRegistry();
+
+    static {
+        Counter counter = METRIC_REGISTRY.counter("m01-counter");
+        counter.inc();
+
+        Histogram histogram = METRIC_REGISTRY.histogram("m02-histogram");
+        histogram.update(5);
+        histogram.update(20);
+        histogram.update(100);
+    }
+
+    @Override
+    protected MetricRegistry getMetricRegistry() {
+        return METRIC_REGISTRY;
+    }
+}

metrics/src/test/java/com/baeldung/metrics/core/MetricsTest.java

@@ -0,0 +1,152 @@
+package com.baeldung.metrics.core;
+
+import com.codahale.metrics.*;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+
+public class MetricsTest {
+    @Test
+    public void whenMarkMeter_thenCorrectRates() throws InterruptedException {
+        Meter meter = new Meter();
+        long initCount = meter.getCount();
+
+        assertThat(initCount, equalTo(0L));
+
+        meter.mark();
+
+        assertThat(meter.getCount(), equalTo(1L));
+
+        meter.mark(20);
+
+        assertThat(meter.getCount(), equalTo(21L));
+
+        // not use assert for these rate values because they change every time when this test is run
+        double meanRate = meter.getMeanRate();
+        double oneMinRate = meter.getOneMinuteRate();
+        double fiveMinRate = meter.getFiveMinuteRate();
+        double fifteenMinRate = meter.getFifteenMinuteRate();
+        System.out.println(meanRate);
+        System.out.println(oneMinRate);
+        System.out.println(fiveMinRate);
+        System.out.println(fifteenMinRate);
+    }
+
+    @Test
+    public void whenInitRatioGauge_thenCorrectRatio() {
+        Gauge<Double> ratioGauge = new AttendanceRatioGauge(15, 20);
+
+        assertThat(ratioGauge.getValue(), equalTo(0.75));
+    }
+
+    @Test
+    public void whenUseCacheGauge_thenCorrectGauge() {
+        Gauge<List<Long>> activeUsersGauge = new ActiveUsersGauge(15, TimeUnit.MINUTES);
+        List<Long> expected = new ArrayList<Long>();
+        expected.add(12L);
+
+        assertThat(activeUsersGauge.getValue(), equalTo(expected));
+    }
+
+    @Test
+    public void whenUseDerivativeGauge_thenCorrectGaugeFromBase() {
+        Gauge<List<Long>> activeUsersGauge = new ActiveUsersGauge(15, TimeUnit.MINUTES);
+        Gauge<Integer> activeUserCountGauge = new ActiveUserCountGauge(activeUsersGauge);
+
+        assertThat(activeUserCountGauge.getValue(), equalTo(1));
+    }
+
+    @Test
+    public void whenIncDecCounter_thenCorrectCount() {
+        Counter counter = new Counter();
+        long initCount = counter.getCount();
+
+        assertThat(initCount, equalTo(0L));
+
+        counter.inc();
+
+        assertThat(counter.getCount(), equalTo(1L));
+
+        counter.inc(11);
+
+        assertThat(counter.getCount(), equalTo(12L));
+
+        counter.dec();
+
+        assertThat(counter.getCount(), equalTo(11L));
+
+        counter.dec(6);
+
+        assertThat(counter.getCount(), equalTo(5L));
+    }
+
+    @Test
+    public void whenUpdateHistogram_thenCorrectDistributionData() {
+        Histogram histogram = new Histogram(new UniformReservoir());
+        histogram.update(5);
+        long count1 = histogram.getCount();
+
+        assertThat(count1, equalTo(1L));
+
+        Snapshot snapshot1 = histogram.getSnapshot();
+        assertThat(snapshot1.getValues().length, equalTo(1));
+        assertThat(snapshot1.getValues()[0], equalTo(5L));
+        assertThat(snapshot1.getMax(), equalTo(5L));
+        assertThat(snapshot1.getMin(), equalTo(5L));
+        assertThat(snapshot1.getMean(), equalTo(5.0));
+        assertThat(snapshot1.getMedian(), equalTo(5.0));
+        assertThat(snapshot1.getStdDev(), equalTo(0.0));
+        assertThat(snapshot1.get75thPercentile(), equalTo(5.0));
+        assertThat(snapshot1.get95thPercentile(), equalTo(5.0));
+        assertThat(snapshot1.get98thPercentile(), equalTo(5.0));
+        assertThat(snapshot1.get99thPercentile(), equalTo(5.0));
+        assertThat(snapshot1.get999thPercentile(), equalTo(5.0));
+
+        histogram.update(20);
+        long count2 = histogram.getCount();
+
+        assertThat(count2, equalTo(2L));
+
+        Snapshot snapshot2 = histogram.getSnapshot();
+
+        assertThat(snapshot2.getValues().length, equalTo(2));
+        assertThat(snapshot2.getValues()[0], equalTo(5L));
+        assertThat(snapshot2.getValues()[1], equalTo(20L));
+        assertThat(snapshot2.getMax(), equalTo(20L));
+        assertThat(snapshot2.getMin(), equalTo(5L));
+        assertThat(snapshot2.getMean(), equalTo(12.5));
+        assertThat(snapshot2.getMedian(), equalTo(12.5));
+        assertEquals(10.6, snapshot2.getStdDev(), 0.1);
+        assertThat(snapshot2.get75thPercentile(), equalTo(20.0));
+        assertThat(snapshot2.get95thPercentile(), equalTo(20.0));
+        assertThat(snapshot2.get98thPercentile(), equalTo(20.0));
+        assertThat(snapshot2.get99thPercentile(), equalTo(20.0));
+        assertThat(snapshot2.get999thPercentile(), equalTo(20.0));
+    }
+
+    @Test
+    public void whenUseTimer_thenCorrectTimerContexts() throws InterruptedException {
+        Timer timer = new Timer();
+        Timer.Context context1 = timer.time();
+        TimeUnit.SECONDS.sleep(5);
+
+        long elapsed1 = context1.stop();
+
+        assertEquals(5000000000L, elapsed1, 10000000);
+        assertThat(timer.getCount(), equalTo(1L));
+        assertEquals(0.2, timer.getMeanRate(), 0.1);
+
+        Timer.Context context2 = timer.time();
+        TimeUnit.SECONDS.sleep(2);
+        context2.close();
+
+        assertThat(timer.getCount(), equalTo(2L));
+        assertEquals(0.3, timer.getMeanRate(), 0.1);
+    }
+}

metrics/src/test/java/com/baeldung/metrics/core/ReporterTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.metrics.core;
+
+import java.util.concurrent.TimeUnit;
+
+import org.junit.Test;
+
+import com.codahale.metrics.*;
+
+public class ReporterTest {
+    @Test
+    public void whenConsoleReporter_thenOutputReport() {
+        MetricRegistry metricRegistry = new MetricRegistry();
+
+        Meter meter = metricRegistry.meter("meter");
+        meter.mark();
+        meter.mark(200);
+        Histogram histogram = metricRegistry.histogram("histogram");
+        histogram.update(12);
+        histogram.update(17);
+        histogram.update(20);
+        Counter counter = metricRegistry.counter("counter");
+        counter.inc();
+        counter.dec();
+        counter.inc();
+        counter.inc();
+        counter.inc();
+        counter.inc();
+
+        ConsoleReporter reporter = ConsoleReporter.forRegistry(metricRegistry).build();
+        reporter.start(5, TimeUnit.MICROSECONDS);
+        reporter.report();
+    }
+}

metrics/src/test/java/com/baeldung/metrics/healthchecks/HealthCheckTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.metrics.healthchecks;
+
+import com.codahale.metrics.health.HealthCheck;
+import com.codahale.metrics.health.HealthCheckRegistry;
+import org.junit.Test;
+
+import java.util.Map;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+public class HealthCheckTest {
+    
+    @Test
+    public void whenUseHealthCheck_thenHealthChecked() {
+        HealthCheckRegistry healthCheckRegistry = new HealthCheckRegistry();
+
+        healthCheckRegistry.register("db", new DatabaseHealthCheck());
+        healthCheckRegistry.register("uc", new UserCenterHealthCheck());
+
+        assertThat(healthCheckRegistry.getNames().size(), equalTo(2));
+
+        Map<String, HealthCheck.Result> results = healthCheckRegistry.runHealthChecks();
+
+        assertFalse(results.isEmpty());
+
+        results.forEach((k, v) -> assertTrue(v.isHealthy()));
+
+        healthCheckRegistry.unregister("uc");
+
+        assertThat(healthCheckRegistry.getNames().size(), equalTo(1));
+    }
+}

pom.xml

@@ -1,6 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.baeldung</groupId>
     <artifactId>parent-modules</artifactId>
@@ -69,12 +68,15 @@
         <module>jsoup</module>
         <module>junit5</module>
 
+        <module>kotlin</module>
+
         <module>log-mdc</module>
         <module>log4j</module>
         <module>log4j2</module>
         <module>lombok</module>
 
         <module>mapstruct</module>
+        <module>metrics</module>
         <module>mockito</module>
         <module>mocks</module>
 
@@ -92,6 +94,7 @@
         <module>resteasy</module>
 
         <module>selenium-junit-testng</module>
+        <module>spark-java</module>
         <module>spring-akka</module>
         <module>spring-amqp</module>
         <module>spring-all</module>
@@ -118,6 +121,7 @@
         <module>spring-hibernate3</module>
         <module>spring-hibernate4</module>
         <module>spring-integration</module>
+        <module>spring-jersey</module>		
         <module>spring-jms</module>
         <module>spring-jooq</module>
         <module>spring-jpa</module>
@@ -161,6 +165,7 @@
         <module>spring-security-rest</module>
         <module>spring-security-x509</module>
         <module>spring-session</module>
+        <module>spring-sleuth</module>
         <module>spring-social-login</module>
         <module>spring-spel</module>
         <module>spring-thymeleaf</module>
@@ -175,6 +180,7 @@
         <module>xml</module>
         <module>xmlunit2</module>
         <module>xstream</module>
+    <module>java-mongodb</module>
   </modules>
 
 </project>