Merge pull request #2 from eugenp/master

test

.gitignore

@@ -66,3 +66,10 @@ jmeter/src/main/resources/*-JMeter.csv
 **/nb-configuration.xml
 core-scala/.cache-main
 core-scala/.cache-tests
+
+
+persistence-modules/hibernate5/transaction.log
+apache-avro/src/main/java/com/baeldung/avro/model/
+jta/transaction-logs/
+software-security/sql-injection-samples/derby.log
+spring-soap/src/main/java/com/baeldung/springsoap/gen/

JGit/pom.xml

@@ -5,9 +5,9 @@
     <groupId>com.baeldung</groupId>
     <artifactId>JGit</artifactId>
     <version>1.0-SNAPSHOT</version>
+	<name>JGit</name>
     <packaging>jar</packaging>
     <url>http://maven.apache.org</url>
-	<name>JGit</name>
 
     <parent>
         <groupId>com.baeldung</groupId>

Twitter4J/pom.xml

@@ -2,8 +2,8 @@
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
     <artifactId>Twitter4J</artifactId>
-    <packaging>jar</packaging>
     <name>Twitter4J</name>
+    <packaging>jar</packaging>
 
     <parent>
         <groupId>com.baeldung</groupId>

akka-http/pom.xml

@@ -23,7 +23,7 @@
 		<dependency>
 			<groupId>com.typesafe.akka</groupId>
 			<artifactId>akka-stream_2.12</artifactId>
-			<version>2.5.11</version>
+			<version>${akka.stream.version}</version>
 		</dependency>
 		<dependency>
 			<groupId>com.typesafe.akka</groupId>
@@ -41,7 +41,6 @@
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-		<java.version>1.8</java.version>
 		<akka.http.version>10.0.11</akka.http.version>
 		<akka.stream.version>2.5.11</akka.stream.version>
 	</properties>

algorithms-genetic/pom.xml

@@ -54,7 +54,6 @@
     </build>
 
     <properties>
-        <lombok.version>1.16.12</lombok.version>
         <commons-math3.version>3.6.1</commons-math3.version>
         <io.jenetics.version>3.7.0</io.jenetics.version>
         <org.assertj.core.version>3.9.0</org.assertj.core.version>

algorithms-miscellaneous-1/README.md

@@ -15,3 +15,5 @@
 - [Find Substrings That Are Palindromes in Java](https://www.baeldung.com/java-palindrome-substrings)
 - [Find the Longest Substring without Repeating Characters](https://www.baeldung.com/java-longest-substring-without-repeated-characters)
 - [Java Two Pointer Technique](https://www.baeldung.com/java-two-pointer-technique)
+- [Permutations of an Array in Java](https://www.baeldung.com/java-array-permutations)
+- [Implementing Simple State Machines with Java Enums](https://www.baeldung.com/java-enum-simple-state-machine)

algorithms-miscellaneous-1/pom.xml

@@ -39,6 +39,11 @@
             <version>${org.assertj.core.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.github.dpaukov</groupId>
+            <artifactId>combinatoricslib3</artifactId>
+            <version>3.3.0</version>
+         </dependency>
     </dependencies>
 
     <build>
@@ -74,11 +79,10 @@
     </reporting>
 
     <properties>
-        <lombok.version>1.16.12</lombok.version>
         <commons-math3.version>3.6.1</commons-math3.version>
         <org.assertj.core.version>3.9.0</org.assertj.core.version>
         <commons-codec.version>1.11</commons-codec.version>
-        <guava.version>25.1-jre</guava.version>
+        <guava.version>27.0.1-jre</guava.version>
     </properties>
 
 </project>

algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/combination/ApacheCommonsCombinationGenerator.java

@@ -0,0 +1,29 @@
+package com.baeldung.algorithms.combination;
+
+import java.util.Arrays;
+import java.util.Iterator;
+
+import org.apache.commons.math3.util.CombinatoricsUtils;
+
+public class ApacheCommonsCombinationGenerator {
+
+    private static final int N = 6;
+    private static final int R = 3;
+
+    /** 
+     * Print all combinations of r elements from a set
+     * @param n - number of elements in set
+     * @param r - number of elements in selection
+     */
+    public static void generate(int n, int r) {
+        Iterator<int[]> iterator = CombinatoricsUtils.combinationsIterator(n, r);
+        while (iterator.hasNext()) {
+            final int[] combination = iterator.next();
+            System.out.println(Arrays.toString(combination));
+        }
+    }
+
+    public static void main(String[] args) {
+        generate(N, R);
+    }
+}

algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/combination/CombinatoricsLibCombinationGenerator.java

@@ -0,0 +1,13 @@
+package com.baeldung.algorithms.combination;
+
+import org.paukov.combinatorics3.Generator;
+
+public class CombinatoricsLibCombinationGenerator {
+
+    public static void main(String[] args) {
+        Generator.combination(0, 1, 2, 3, 4, 5)
+            .simple(3)
+            .stream()
+            .forEach(System.out::println);
+    }
+}

algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/combination/GuavaCombinationsGenerator.java

@@ -0,0 +1,17 @@
+package com.baeldung.algorithms.combination;
+
+import java.util.Arrays;
+import java.util.Set;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Sets;
+
+public class GuavaCombinationsGenerator {
+
+    public static void main(String[] args) {
+
+        Set<Set<Integer>> combinations = Sets.combinations(ImmutableSet.of(0, 1, 2, 3, 4, 5), 3);
+        System.out.println(combinations.size());
+        System.out.println(Arrays.toString(combinations.toArray()));
+    }
+}

algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/combination/IterativeCombinationGenerator.java

@@ -0,0 +1,52 @@
+package com.baeldung.algorithms.combination;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class IterativeCombinationGenerator {
+
+    private static final int N = 5;
+    private static final int R = 2;
+
+    /**
+     * Generate all combinations of r elements from a set
+     * @param n the number of elements in input set
+     * @param r the number of elements in a combination
+     * @return the list containing all combinations
+     */
+    public List<int[]> generate(int n, int r) {
+        List<int[]> combinations = new ArrayList<>();
+        int[] combination = new int[r];
+
+        // initialize with lowest lexicographic combination
+        for (int i = 0; i < r; i++) {
+            combination[i] = i;
+        }
+
+        while (combination[r - 1] < n) {
+            combinations.add(combination.clone());
+
+            // generate next combination in lexicographic order
+            int t = r - 1;
+            while (t != 0 && combination[t] == n - r + t) {
+                t--;
+            }
+            combination[t]++;
+            for (int i = t + 1; i < r; i++) {
+                combination[i] = combination[i - 1] + 1;
+            }
+        }
+
+        return combinations;
+    }
+
+    public static void main(String[] args) {
+        IterativeCombinationGenerator generator = new IterativeCombinationGenerator();
+        List<int[]> combinations = generator.generate(N, R);
+        System.out.println(combinations.size());
+        for (int[] combination : combinations) {
+            System.out.println(Arrays.toString(combination));
+        }
+    }
+}

algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/combination/SelectionRecursiveCombinationGenerator.java

@@ -0,0 +1,53 @@
+package com.baeldung.algorithms.combination;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class SelectionRecursiveCombinationGenerator {
+
+    private static final int N = 6;
+    private static final int R = 3;
+
+    /** 
+     * Generate all combinations of r elements from a set
+     * @param n - number of elements in input set
+     * @param r - number of elements to be chosen
+     * @return the list containing all combinations
+     */
+    public List<int[]> generate(int n, int r) {
+        List<int[]> combinations = new ArrayList<>();
+        helper(combinations, new int[r], 0, n - 1, 0);
+        return combinations;
+    }
+
+    /** 
+     * Choose elements from set by recursing over elements selected
+     * @param combinations - List to store generated combinations
+     * @param data - current combination
+     * @param start - starting element of remaining set
+     * @param end - last element of remaining set
+     * @param index - number of elements chosen so far.
+     */
+    private void helper(List<int[]> combinations, int data[], int start, int end, int index) {
+        if (index == data.length) {
+            int[] combination = data.clone();
+            combinations.add(combination);
+        } else {
+            int max = Math.min(end, end + 1 - data.length + index);
+            for (int i = start; i <= max; i++) {
+                data[index] = i;
+                helper(combinations, data, i + 1, end, index + 1);
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        SelectionRecursiveCombinationGenerator generator = new SelectionRecursiveCombinationGenerator();
+        List<int[]> combinations = generator.generate(N, R);
+        for (int[] combination : combinations) {
+            System.out.println(Arrays.toString(combination));
+        }
+        System.out.printf("generated %d combinations of %d items from %d ", combinations.size(), R, N);
+    }
+}

algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/combination/SetRecursiveCombinationGenerator.java

@@ -0,0 +1,50 @@
+package com.baeldung.algorithms.combination;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class SetRecursiveCombinationGenerator {
+
+    private static final int N = 5;
+    private static final int R = 2;
+
+    /** 
+     * Generate all combinations of r elements from a set
+     * @param n - number of elements in set
+     * @param r - number of elements in selection
+     * @return the list containing all combinations
+     */
+    public List<int[]> generate(int n, int r) {
+        List<int[]> combinations = new ArrayList<>();
+        helper(combinations, new int[r], 0, n-1, 0);
+        return combinations;
+    }
+
+    /**
+     * @param combinations - List to contain the generated combinations
+     * @param data - List of elements in the selection
+     * @param start - index of the starting element in the remaining set
+     * @param end - index of the last element in the set  
+     * @param index - number of elements selected so far
+     */
+    private void helper(List<int[]> combinations, int data[], int start, int end, int index) {
+        if (index == data.length) {
+            int[] combination = data.clone();
+            combinations.add(combination);
+        } else if (start <= end) {
+            data[index] = start;
+            helper(combinations, data, start + 1, end, index + 1);
+            helper(combinations, data, start + 1, end, index);
+        }
+    }
+
+    public static void main(String[] args) {
+        SetRecursiveCombinationGenerator generator = new SetRecursiveCombinationGenerator();
+        List<int[]> combinations = generator.generate(N, R);
+        for (int[] combination : combinations) {
+            System.out.println(Arrays.toString(combination));
+        }
+        System.out.printf("generated %d combinations of %d items from %d ", combinations.size(), R, N);
+    }
+}

algorithms-miscellaneous-1/src/test/java/com/baeldung/algorithms/combination/CombinationUnitTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.algorithms.combination;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.List;
+
+import org.junit.Test;
+
+public class CombinationUnitTest {
+
+    private static final int N = 5;
+    private static final int R = 3;
+    private static final int nCr = 10;
+      
+    @Test
+    public void givenSetAndSelectionSize_whenCalculatedUsingSetRecursiveAlgorithm_thenExpectedCount() {
+        SetRecursiveCombinationGenerator generator = new SetRecursiveCombinationGenerator();
+        List<int[]> selection = generator.generate(N, R);
+        assertEquals(nCr, selection.size());
+    }
+
+    @Test
+    public void givenSetAndSelectionSize_whenCalculatedUsingSelectionRecursiveAlgorithm_thenExpectedCount() {
+        SelectionRecursiveCombinationGenerator generator = new SelectionRecursiveCombinationGenerator();
+        List<int[]> selection = generator.generate(N, R);
+        assertEquals(nCr, selection.size());
+    }
+    
+    @Test
+    public void givenSetAndSelectionSize_whenCalculatedUsingIterativeAlgorithm_thenExpectedCount() {
+        IterativeCombinationGenerator generator = new IterativeCombinationGenerator();
+        List<int[]> selection = generator.generate(N, R);
+        assertEquals(nCr, selection.size());
+    }
+}

algorithms-miscellaneous-2/pom.xml

@@ -68,7 +68,7 @@
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>cobertura-maven-plugin</artifactId>
-                <version>2.7</version>
+                <version>${cobertura-maven-plugin.version}</version>
                 <configuration>
                     <instrumentation>
                         <ignores>
@@ -84,13 +84,13 @@
     </reporting>
 
     <properties>
-        <lombok.version>1.16.12</lombok.version>
         <commons-math3.version>3.6.1</commons-math3.version>
         <tradukisto.version>1.0.1</tradukisto.version>
         <org.jgrapht.core.version>1.0.1</org.jgrapht.core.version>
         <org.jgrapht.ext.version>1.0.1</org.jgrapht.ext.version>
         <org.assertj.core.version>3.9.0</org.assertj.core.version>
         <commons-codec.version>1.11</commons-codec.version>
+        <cobertura-maven-plugin.version>2.7</cobertura-maven-plugin.version>
     </properties>
 
 </project>

algorithms-sorting/pom.xml

@@ -49,7 +49,6 @@
     </build>
 
     <properties>
-        <lombok.version>1.16.12</lombok.version>
         <commons-math3.version>3.6.1</commons-math3.version>
         <org.assertj.core.version>3.9.0</org.assertj.core.version>
         <commons-codec.version>1.11</commons-codec.version>

animal-sniffer-mvn-plugin/pom.xml

@@ -3,9 +3,9 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.baeldung</groupId>
     <artifactId>animal-sniffer-mvn-plugin</artifactId>
-    <packaging>jar</packaging>
     <version>1.0-SNAPSHOT</version>
     <name>animal-sniffer-mvn-plugin</name>
+    <packaging>jar</packaging>
     <url>http://maven.apache.org</url>
 
     <parent>

annotations/pom.xml

@@ -3,8 +3,8 @@
     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>
     <artifactId>annotations</artifactId>
-    <packaging>pom</packaging>
     <name>annotations</name>
+    <packaging>pom</packaging>
     
     <parent>
         <artifactId>parent-modules</artifactId>

apache-avro/pom.xml

@@ -7,14 +7,6 @@
     <version>0.0.1-SNAPSHOT</version>
 	<name>apache-avro</name>
 
-    <properties>
-        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <compiler-plugin.version>3.5</compiler-plugin.version>
-        <avro.version>1.8.2</avro.version>
-        <java.version>1.8</java.version>
-        <slf4j.version>1.7.25</slf4j.version>
-    </properties>
-	
     <parent>
         <groupId>com.baeldung</groupId>
         <artifactId>parent-modules</artifactId>
@@ -85,4 +77,12 @@
             </plugin>
         </plugins>
     </build>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <compiler-plugin.version>3.5</compiler-plugin.version>
+        <avro.version>1.8.2</avro.version>
+        <slf4j.version>1.7.25</slf4j.version>
+    </properties>
+	
 </project>

apache-curator/pom.xml

@@ -3,8 +3,8 @@
     <modelVersion>4.0.0</modelVersion>
     <artifactId>apache-curator</artifactId>
     <version>0.0.1-SNAPSHOT</version>
-    <packaging>jar</packaging>
 	<name>apache-curator</name>
+    <packaging>jar</packaging>
 
     <parent>
         <groupId>com.baeldung</groupId>
@@ -39,7 +39,7 @@
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
-            <version>${jackson-databind.version}</version>
+            <version>${jackson.version}</version>
         </dependency>
         <!-- test scoped -->
         <dependency>
@@ -59,7 +59,6 @@
     <properties>
         <curator.version>4.0.1</curator.version>
         <zookeeper.version>3.4.11</zookeeper.version>
-        <jackson-databind.version>2.9.7</jackson-databind.version>
         <!-- testing -->
         <assertj.version>3.6.1</assertj.version>
         <avaitility.version>1.7.0</avaitility.version>

apache-geode/pom.xml

@@ -13,22 +13,6 @@
         <version>1.0.0-SNAPSHOT</version>
     </parent>
 
-    <properties>
-        <geode.core>1.6.0</geode.core>
-    </properties>
-    <build>
-        <plugins>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-compiler-plugin</artifactId>
-                <configuration>
-                    <source>1.8</source>
-                    <target>1.8</target>
-                </configuration>
-            </plugin>
-        </plugins>
-    </build>
-
     <dependencies>
         <dependency>
             <groupId>org.apache.geode</groupId>
@@ -38,8 +22,24 @@
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>RELEASE</version>
+            <version>${junit.version}</version>
         </dependency>
     </dependencies>
     
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>${java.version}</source>
+                    <target>${java.version}</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+	
+    <properties>
+        <geode.core>1.6.0</geode.core>
+    </properties>
 </project>

apache-meecrowave/pom.xml

@@ -7,51 +7,58 @@
     <name>apache-meecrowave</name>
     <description>A sample REST API application with Meecrowave</description>
 
-    <properties>
-        <maven.compiler.source>1.8</maven.compiler.source>
-        <maven.compiler.target>1.8</maven.compiler.target>
-    </properties>
     <dependencies>
         <!-- https://mvnrepository.com/artifact/org.apache.meecrowave/meecrowave-core -->
         <dependency>
             <groupId>org.apache.meecrowave</groupId>
             <artifactId>meecrowave-core</artifactId>
-            <version>1.2.1</version>
+            <version>${meecrowave-core.version}</version>
         </dependency>
         <!-- https://mvnrepository.com/artifact/org.apache.meecrowave/meecrowave-jpa -->
         <dependency>
             <groupId>org.apache.meecrowave</groupId>
             <artifactId>meecrowave-jpa</artifactId>
-            <version>1.2.1</version>
+            <version>${meecrowave-jpa.version}</version>
         </dependency>
 
         <dependency>
             <groupId>com.squareup.okhttp3</groupId>
             <artifactId>okhttp</artifactId>
-            <version>3.10.0</version>
+            <version>${okhttp.version}</version>
         </dependency>
         <dependency>
             <groupId>org.apache.meecrowave</groupId>
             <artifactId>meecrowave-junit</artifactId>
-            <version>1.2.0</version>
+            <version>${meecrowave-junit.version}</version>
             <scope>test</scope>
         </dependency>
         <!-- https://mvnrepository.com/artifact/junit/junit -->
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>4.10</version>
+            <version>${junit.version}</version>
             <scope>test</scope>
         </dependency>
-
     </dependencies>
+	
     <build>
         <plugins>
             <plugin>
                 <groupId>org.apache.meecrowave</groupId>
                 <artifactId>meecrowave-maven-plugin</artifactId>
-                <version>1.2.1</version>
+                <version>${meecrowave-maven-plugin.version}</version>
             </plugin>
         </plugins>
     </build>
+	
+    <properties>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+		<junit.version>4.10</junit.version>
+		<meecrowave-junit.version>1.2.0</meecrowave-junit.version>
+		<okhttp.version>3.10.0</okhttp.version>
+		<meecrowave-jpa.version>1.2.1</meecrowave-jpa.version>
+		<meecrowave-core.version>1.2.1</meecrowave-core.version>
+		<meecrowave-maven-plugin.version>1.2.1</meecrowave-maven-plugin.version>
+    </properties>
 </project>

apache-pulsar/pom.xml

@@ -11,12 +11,14 @@
         <dependency>
             <groupId>org.apache.pulsar</groupId>
             <artifactId>pulsar-client</artifactId>
-            <version>2.1.1-incubating</version>
+            <version>${pulsar-client.version}</version>
             <scope>compile</scope>
         </dependency>
     </dependencies>
+	
     <properties>
         <maven.compiler.target>1.8</maven.compiler.target>
         <maven.compiler.source>1.8</maven.compiler.source>
+		<pulsar-client.version>2.1.1-incubating</pulsar-client.version>
     </properties>
 </project>

apache-solrj/pom.xml

@@ -4,8 +4,8 @@
     <groupId>com.baeldung</groupId>
     <artifactId>apache-solrj</artifactId>
     <version>0.0.1-SNAPSHOT</version>
-    <packaging>jar</packaging>
     <name>apache-solrj</name>
+    <packaging>jar</packaging>
 
     <parent>
         <groupId>com.baeldung</groupId>

apache-spark/README.md

@@ -1,3 +1,4 @@
 ### Relevant articles
 
 - [Introduction to Apache Spark](http://www.baeldung.com/apache-spark)
+- [Building a Data Pipeline with Kafka, Spark Streaming and Cassandra](https://www.baeldung.com/kafka-spark-data-pipeline)

apache-spark/pom.xml

@@ -4,8 +4,8 @@
     <groupId>com.baeldung</groupId>
     <artifactId>apache-spark</artifactId>
     <version>1.0-SNAPSHOT</version>
-    <packaging>jar</packaging>
     <name>apache-spark</name>
+    <packaging>jar</packaging>
     <url>http://maven.apache.org</url>
 
     <parent>
@@ -54,10 +54,10 @@
     	  	<plugin>
     			<groupId>org.apache.maven.plugins</groupId>
     			<artifactId>maven-compiler-plugin</artifactId>
-    			<version>3.2</version>
+    			<version>${maven-compiler-plugin.version}</version>
     			<configuration>
-      				<source>1.8</source>
+      				<source>${java.version}</source>
-      				<target>1.8</target>
+      				<target>${java.version}</target>
     			</configuration>
   			</plugin>
       		<plugin>
@@ -85,6 +85,7 @@
         <org.apache.spark.spark-streaming-kafka.version>2.3.0</org.apache.spark.spark-streaming-kafka.version>
         <com.datastax.spark.spark-cassandra-connector.version>2.3.0</com.datastax.spark.spark-cassandra-connector.version>
         <com.datastax.spark.spark-cassandra-connector-java.version>1.5.2</com.datastax.spark.spark-cassandra-connector-java.version>
+		<maven-compiler-plugin.version>3.2</maven-compiler-plugin.version>
     </properties>
 
 </project>

apache-velocity/pom.xml

@@ -4,8 +4,8 @@
     <groupId>com.baeldung</groupId>
     <version>0.1-SNAPSHOT</version>
     <artifactId>apache-velocity</artifactId>
-    <packaging>war</packaging>
     <name>apache-velocity</name>
+    <packaging>war</packaging>
 
     <parent>
         <groupId>com.baeldung</groupId>

aws-lambda/pom.xml

@@ -5,8 +5,8 @@
     <groupId>com.baeldung</groupId>
     <artifactId>aws-lambda</artifactId>
     <version>0.1.0-SNAPSHOT</version>
-    <packaging>jar</packaging>
     <name>aws-lambda</name>
+    <packaging>jar</packaging>
 
     <parent>
         <artifactId>parent-modules</artifactId>

aws/README.md

@@ -4,7 +4,6 @@
 - [AWS S3 with Java](http://www.baeldung.com/aws-s3-java)
 - [AWS Lambda With Java](http://www.baeldung.com/java-aws-lambda)
 - [Managing EC2 Instances in Java](http://www.baeldung.com/ec2-java)
-- [http://www.baeldung.com/aws-s3-multipart-upload](https://github.com/eugenp/tutorials/tree/master/aws)
 - [Multipart Uploads in Amazon S3 with Java](http://www.baeldung.com/aws-s3-multipart-upload)
 - [Integration Testing with a Local DynamoDB Instance](http://www.baeldung.com/dynamodb-local-integration-tests)
 - [Using the JetS3t Java Client With Amazon S3](http://www.baeldung.com/jets3t-amazon-s3)

aws/pom.xml

@@ -4,8 +4,8 @@
     <groupId>com.baeldung</groupId>
     <artifactId>aws</artifactId>
     <version>0.1.0-SNAPSHOT</version>
-    <packaging>jar</packaging>
     <name>aws</name>
+    <packaging>jar</packaging>
 
     <parent>
         <groupId>com.baeldung</groupId>

axon/pom.xml

@@ -36,7 +36,7 @@
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-autoconfigure</artifactId>
-            <version>2.1.1.RELEASE</version>
+            <version>${spring-boot.version}</version>
             <scope>compile</scope>
         </dependency>
 

azure/pom.xml

@@ -5,9 +5,9 @@
     <groupId>com.baeldung</groupId>
     <artifactId>azure</artifactId>
     <version>0.1</version>
-    <packaging>war</packaging>
     <name>azure</name>
     <description>Demo project for Spring Boot on Azure</description>
+    <packaging>war</packaging>
 
     <parent>
         <artifactId>parent-boot-2</artifactId>
@@ -127,7 +127,6 @@
         <docker.image.prefix>${azure.containerRegistry}.azurecr.io</docker.image.prefix>
         <docker-maven-plugin.version>1.1.0</docker-maven-plugin.version>
         <azure-webapp-maven-plugin.version>1.1.0</azure-webapp-maven-plugin.version>
-        <java.version>1.8</java.version>
     </properties>
 
 </project>

blade/pom.xml

@@ -3,12 +3,12 @@
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
 
     <modelVersion>4.0.0</modelVersion>
-    <artifactId>blade</artifactId>
-    <name>blade</name>
-
     <!-- WITH THIS mvn integration-test DOES WORK -->
     <groupId>com.baeldung</groupId>
+    <artifactId>blade</artifactId>
     <version>1.0.0-SNAPSHOT</version>
+    <name>blade</name>
+
 
     <!-- WITH THIS mvn integration-test DOESN'T WORK -->
     <!-- <parent> -->
@@ -17,35 +17,30 @@
     <!-- <version>1.0.0-SNAPSHOT</version> -->
     <!-- </parent> -->
 
-    <properties>
-        <maven.compiler.source>1.8</maven.compiler.source>
-        <maven.compiler.target>1.8</maven.compiler.target>
-    </properties>
-
     <dependencies>
         <dependency>
             <groupId>com.bladejava</groupId>
             <artifactId>blade-mvc</artifactId>
-            <version>2.0.14.RELEASE</version>
+            <version>${blade-mvc.version}</version>
         </dependency>
 
         <dependency>
             <groupId>org.webjars</groupId>
             <artifactId>bootstrap</artifactId>
-            <version>4.2.1</version>
+            <version>${bootstrap.version}</version>
         </dependency>
 
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-lang3</artifactId>
-            <version>3.8.1</version>
+            <version>${commons-lang3.version}</version>
         </dependency>
 
         <!-- PROVIDED -->
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
-            <version>1.18.4</version>
+            <version>${lombok.version}</version>
             <scope>provided</scope>
         </dependency>
 
@@ -53,31 +48,31 @@
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>4.12</version>
+            <version>${junit.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
-            <version>3.11.1</version>
+            <version>${assertj-core.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.apache.httpcomponents</groupId>
             <artifactId>httpclient</artifactId>
-            <version>4.5.6</version>
+            <version>${httpclient.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.apache.httpcomponents</groupId>
             <artifactId>httpmime</artifactId>
-            <version>4.5.6</version>
+            <version>${httpmime.version}</version>
             <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.apache.httpcomponents</groupId>
             <artifactId>httpcore</artifactId>
-            <version>4.4.10</version>
+            <version>${httpcore.version}</version>
             <scope>test</scope>
         </dependency>
     </dependencies>
@@ -88,6 +83,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-surefire-plugin</artifactId>
+                <version>${maven-surefire-plugin.version}</version>
                 <configuration>
                     <forkCount>3</forkCount>
                     <reuseForks>true</reuseForks>
@@ -100,7 +96,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-failsafe-plugin</artifactId>
-                <version>3.0.0-M3</version>
+                <version>${maven-failsafe-plugin.version}</version>
                 <configuration>
                     <includes>
                         <include>**/*LiveTest.java</include>
@@ -119,7 +115,7 @@
             <plugin>
                 <groupId>com.bazaarvoice.maven.plugins</groupId>
                 <artifactId>process-exec-maven-plugin</artifactId>
-                <version>0.7</version>
+                <version>${process-exec-maven-plugin.version}</version>
                 <executions>
                     <!--Start Blade -->
                     <execution>
@@ -177,13 +173,33 @@
                 </executions>
             </plugin>
             <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
                 <configuration>
-                    <source>1.8</source>
+                    <source>${maven.compiler.source}</source>
-                    <target>1.8</target>
+                    <target>${maven.compiler.target}</target>
                     <encoding>UTF-8</encoding>
                 </configuration>
             </plugin>
         </plugins>
     </build>
+	
+    <properties>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+		<blade-mvc.version>2.0.14.RELEASE</blade-mvc.version>
+		<bootstrap.version>4.2.1</bootstrap.version>
+		<commons-lang3.version>3.8.1</commons-lang3.version>
+		<lombok.version>1.18.4</lombok.version>
+		<junit.version>4.12</junit.version>
+		<httpclient.version>4.5.6</httpclient.version>
+		<httpmime.version>4.5.6</httpmime.version>
+		<httpcore.version>4.4.10</httpcore.version>
+		<assertj-core.version>3.11.1</assertj-core.version>
+		<maven-failsafe-plugin.version>3.0.0-M3</maven-failsafe-plugin.version>
+		<process-exec-maven-plugin.version>0.7</process-exec-maven-plugin.version>
+		<maven-surefire-plugin.version>2.21.0</maven-surefire-plugin.version>
+		<maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
+    </properties>
 </project>

bootique/pom.xml

@@ -3,9 +3,9 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.baeldung.bootique</groupId>
     <artifactId>bootique</artifactId>
-    <packaging>jar</packaging>
     <version>1.0-SNAPSHOT</version>
     <name>bootique</name>
+    <packaging>jar</packaging>
     <url>http://maven.apache.org</url>
 
     <parent>

cas/cas-secured-app/pom.xml

@@ -3,9 +3,9 @@
     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>
     <artifactId>cas-secured-app</artifactId>
-    <packaging>jar</packaging>
     <name>cas-secured-app</name>
     <description>Demo project for CAS</description>
+    <packaging>jar</packaging>
 
     <parent>
         <artifactId>parent-boot-1</artifactId>

cas/pom.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
+    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>
+    <artifactId>cas</artifactId>
+    <name>cas</name>
+    <packaging>pom</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>..</relativePath>
+    </parent>
+
+    <modules>
+        <module>cas-secured-app</module>
+        <module>cas-server</module>
+    </modules>
+
+</project>

cdi/pom.xml

@@ -59,13 +59,13 @@
             <scope>test</scope>
         </dependency>
     </dependencies>
+	
     <properties>
         <cdi-api.version>2.0.SP1</cdi-api.version>
         <weld-se-core.version>3.0.5.Final</weld-se-core.version>
         <aspectjweaver.version>1.9.2</aspectjweaver.version>
         <hamcrest-core.version>1.3</hamcrest-core.version>
         <assertj-core.version>3.10.0</assertj-core.version>
-        <junit.version>4.12</junit.version>
         <spring.version>5.1.2.RELEASE</spring.version>
     </properties>
 </project>

checker-plugin/pom.xml

@@ -3,9 +3,9 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.baeldung</groupId>
     <artifactId>checker-plugin</artifactId>
-    <packaging>jar</packaging>
     <version>1.0-SNAPSHOT</version>
     <name>checker-plugin</name>
+    <packaging>jar</packaging>
     <url>http://maven.apache.org</url>
 
     <parent>

core-groovy/README.md

@@ -4,3 +4,7 @@
 
 - [JDBC with Groovy](http://www.baeldung.com/jdbc-groovy)
 - [Working with JSON in Groovy](http://www.baeldung.com/groovy-json)
+- [Reading a File in Groovy](https://www.baeldung.com/groovy-file-read)
+- [Types of Strings in Groovy](https://www.baeldung.com/groovy-strings)
+- [A Quick Guide to Iterating a Map in Groovy](https://www.baeldung.com/groovy-map-iterating)
+- [An Introduction to Traits in Groovy](https://www.baeldung.com/groovy-traits)

core-groovy/pom.xml

@@ -23,6 +23,12 @@
             <groupId>org.codehaus.groovy</groupId>
             <artifactId>groovy-all</artifactId>
             <version>${groovy-all.version}</version>
+            <type>pom</type>
+        </dependency>
+        <dependency>
+            <groupId>org.codehaus.groovy</groupId>
+            <artifactId>groovy-dateutil</artifactId>
+            <version>${groovy.version}</version>
         </dependency>
         <dependency>
             <groupId>org.codehaus.groovy</groupId>
@@ -103,9 +109,12 @@
 
     <properties>
         <junit.platform.version>1.0.0</junit.platform.version>
-        <groovy.version>2.4.13</groovy.version>
+<!--         <groovy.version>2.4.13</groovy.version> -->
-        <groovy-all.version>2.4.13</groovy-all.version>
+<!--         <groovy-all.version>2.4.13</groovy-all.version> -->
-        <groovy-sql.version>2.4.13</groovy-sql.version>
+<!--         <groovy-sql.version>2.4.13</groovy-sql.version> -->
+        <groovy.version>2.5.6</groovy.version>
+        <groovy-all.version>2.5.6</groovy-all.version>
+        <groovy-sql.version>2.5.6</groovy-sql.version>
         <hsqldb.version>2.4.0</hsqldb.version>
         <spock-core.version>1.1-groovy-2.4</spock-core.version>
         <gmavenplus-plugin.version>1.6</gmavenplus-plugin.version>

core-groovy/src/main/groovy/com/baeldung/file/ReadFile.groovy

@@ -0,0 +1,107 @@
+package com.baeldung.file
+
+class ReadFile {
+
+    /**
+     * reads file content line by line using withReader and reader.readLine
+     * @param filePath
+     * @return
+     */
+    int readFileLineByLine(String filePath) {
+        File file = new File(filePath)
+        def line, noOfLines = 0;
+        file.withReader { reader ->
+            while ((line = reader.readLine())!=null)
+            {
+                println "${line}"
+                noOfLines++
+            }
+        }
+        return noOfLines
+    }
+
+    /**
+     * reads file content in list of lines
+     * @param filePath
+     * @return
+     */
+    List<String> readFileInList(String filePath) {
+        File file = new File(filePath)
+        def lines = file.readLines()
+        return lines
+    }
+
+    /**
+     * reads file content in string using File.text
+     * @param filePath
+     * @return
+     */
+    String readFileString(String filePath) {
+        File file = new File(filePath)
+        String fileContent = file.text
+        return fileContent
+    }
+
+    /**
+     * reads file content in string with encoding using File.getText
+     * @param filePath
+     * @return
+     */
+    String readFileStringWithCharset(String filePath) {
+        File file = new File(filePath)
+        String utf8Content = file.getText("UTF-8")
+        return utf8Content
+    }
+
+    /**
+     * reads content of binary file and returns byte array
+     * @param filePath
+     * @return
+     */
+    byte[] readBinaryFile(String filePath) {
+        File file = new File(filePath)
+        byte[] binaryContent = file.bytes
+        return binaryContent
+    }
+    
+    /**
+     * More Examples of reading a file 
+     * @return
+     */
+    def moreExamples() {
+        
+        //with reader with utf-8
+        new File("src/main/resources/utf8Content.html").withReader('UTF-8') { reader ->
+            def line
+            while ((line = reader.readLine())!=null) { 
+                println "${line}"
+            }
+        }
+        
+        //collect api
+        def list = new File("src/main/resources/fileContent.txt").collect {it}
+                
+        //as operator
+        def array = new File("src/main/resources/fileContent.txt") as String[]
+              
+        //eachline  
+        new File("src/main/resources/fileContent.txt").eachLine { line ->
+            println line
+        }
+        
+        //newInputStream with eachLine
+        def is = new File("src/main/resources/fileContent.txt").newInputStream()
+        is.eachLine {
+            println it
+        }
+        is.close()
+        
+        //withInputStream
+        new File("src/main/resources/fileContent.txt").withInputStream { stream ->
+            stream.eachLine { line ->
+                println line
+            }
+        }
+    }
+
+}

core-groovy/src/main/groovy/com/baeldung/io/Task.groovy

@@ -0,0 +1,8 @@
+package com.baeldung.io
+
+class Task implements Serializable {
+    String description
+    Date startDate
+    Date dueDate
+    int status
+}

core-groovy/src/main/groovy/com/baeldung/strings/Concatenate.groovy

@@ -0,0 +1,43 @@
+package com.baeldung.strings;
+
+class Concatenate {
+    String first = 'Hello'
+    String last = 'Groovy'
+  
+    String doSimpleConcat() {
+        return 'My name is ' + first + ' ' + last
+    }
+
+    String doConcatUsingGString() {
+        return "My name is $first $last"
+    }
+
+    String doConcatUsingGStringClosures() {
+        return "My name is ${-> first} ${-> last}"
+    }
+
+    String doConcatUsingStringConcatMethod() {
+        return 'My name is '.concat(first).concat(' ').concat(last)
+    }
+
+    String doConcatUsingLeftShiftOperator() {
+        return 'My name is ' << first << ' ' << last
+    }
+    
+    String doConcatUsingArrayJoinMethod() {
+        return ['My name is', first, last].join(' ')
+    }
+
+    String doConcatUsingArrayInjectMethod() {
+        return  [first,' ', last]
+          .inject(new StringBuffer('My name is '), { initial, name -> initial.append(name); return initial }).toString()
+    }
+ 
+    String doConcatUsingStringBuilder() {
+        return new StringBuilder().append('My name is ').append(first).append(' ').append(last)
+    }
+
+    String doConcatUsingStringBuffer() {
+        return new StringBuffer().append('My name is ').append(first).append(' ').append(last)
+    }
+}

core-groovy/src/main/groovy/com/baeldung/traits/AnimalTrait.groovy

@@ -0,0 +1,8 @@
+package com.baeldung.traits
+
+trait AnimalTrait {
+    
+    String basicBehavior() {
+        return "Animalistic!!"
+    }
+}

core-groovy/src/main/groovy/com/baeldung/traits/Car.groovy

@@ -0,0 +1,3 @@
+package com.baeldung
+
+class Car implements VehicleTrait {}

core-groovy/src/main/groovy/com/baeldung/traits/Dog.groovy

@@ -0,0 +1,9 @@
+package com.baeldung.traits
+
+class Dog implements WalkingTrait, SpeakingTrait {
+     
+    String speakAndWalk() {
+        WalkingTrait.super.speakAndWalk()
+    }
+    
+}

core-groovy/src/main/groovy/com/baeldung/traits/Employee.groovy

@@ -0,0 +1,12 @@
+package com.baeldung.traits
+
+class Employee implements UserTrait {
+    
+    String name() {
+        return 'Bob'
+    }
+    
+    String lastName() {
+        return "Marley"
+    }
+}

core-groovy/src/main/groovy/com/baeldung/traits/Human.groovy

@@ -0,0 +1,6 @@
+package com.baeldung.traits
+
+interface Human {
+    
+    String lastName()
+}

core-groovy/src/main/groovy/com/baeldung/traits/SpeakingTrait.groovy

@@ -0,0 +1,13 @@
+package com.baeldung.traits
+
+trait SpeakingTrait {
+    
+    String basicAbility() {
+        return "Speaking!!"
+    }
+    
+    String speakAndWalk() {
+        return "Speak and walk!!"
+    }
+    
+}

core-groovy/src/main/groovy/com/baeldung/traits/UserTrait.groovy

@@ -0,0 +1,36 @@
+package com.baeldung.traits
+
+trait UserTrait implements Human {
+    
+    String sayHello() {
+        return "Hello!"
+    }
+    
+    abstract String name()
+    
+    String showName() {
+       return "Hello, ${name()}!"
+    }
+
+    private String greetingMessage() {
+        return 'Hello, from a private method!'
+    }
+    
+    String greet() {
+        def msg = greetingMessage()
+        println msg
+        msg
+    }
+    
+    def self() {
+        return this 
+    }
+    
+    String showLastName() {
+        return "Hello, ${lastName()}!"
+    }
+    
+    String email
+    String address
+}
+    

core-groovy/src/main/groovy/com/baeldung/traits/VehicleTrait.groovy

@@ -0,0 +1,9 @@
+package com.baeldung
+
+trait VehicleTrait extends WheelTrait {
+    
+    String showWheels() {
+        return "Num of Wheels $noOfWheels" 
+    }
+    
+}

core-groovy/src/main/groovy/com/baeldung/traits/WalkingTrait.groovy

@@ -0,0 +1,13 @@
+package com.baeldung.traits
+
+trait WalkingTrait {
+    
+    String basicAbility() {
+        return "Walking!!"
+    }
+    
+    String speakAndWalk() {
+        return "Walk and speak!!"
+    }
+    
+}

core-groovy/src/main/groovy/com/baeldung/traits/WheelTrait.groovy

@@ -0,0 +1,7 @@
+package com.baeldung
+
+trait WheelTrait {
+    
+    int noOfWheels
+    
+}

core-groovy/src/main/resources/fileContent.txt

@@ -0,0 +1,3 @@
+Line 1 : Hello World!!!
+Line 2 : This is a file content.
+Line 3 : String content

core-groovy/src/main/resources/ioInput.txt

@@ -0,0 +1,4 @@
+First line of text
+Second line of text
+Third line of text
+Fourth line of text

core-groovy/src/main/resources/ioOutput.txt

@@ -0,0 +1,3 @@
+Line one of output example
+Line two of output example
+Line three of output example

core-groovy/src/main/resources/utf8Content.html

@@ -0,0 +1,12 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
+    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml">
+<meta charset="UTF-8">
+<body>
+<pre>
+ᚠᛇᚻ᛫ᛒᛦᚦ᛫ᚠᚱᚩᚠᚢᚱ᛫ᚠᛁᚱᚪ᛫ᚷᛖᚻᚹᛦᛚᚳᚢᛗ
+ᛋᚳᛖᚪᛚ᛫ᚦᛖᚪᚻ᛫ᛗᚪᚾᚾᚪ᛫ᚷᛖᚻᚹᛦᛚᚳ᛫ᛗᛁᚳᛚᚢᚾ᛫ᚻᛦᛏ᛫ᛞᚫᛚᚪᚾ
+ᚷᛁᚠ᛫ᚻᛖ᛫ᚹᛁᛚᛖ᛫ᚠᚩᚱ᛫ᛞᚱᛁᚻᛏᚾᛖ᛫ᛞᚩᛗᛖᛋ᛫ᚻᛚᛇᛏᚪᚾ
+</pre>
+</body>
+</html>

core-groovy/src/test/groovy/com/baeldung/date/DateTest.groovy

@@ -0,0 +1,57 @@
+package com.baeldung.groovy.sql
+
+import static org.junit.Assert.*
+import java.util.Calendar.*
+import java.time.LocalDate 
+import java.text.SimpleDateFormat 
+import org.junit.Test
+
+
+class DateTest {
+
+    def dateStr = "2019-02-28"
+    def pattern = "yyyy-MM-dd"  
+
+    @Test
+    void whenGetStringRepresentation_thenCorrectlyConvertIntoDate() {
+        def dateFormat = new SimpleDateFormat(pattern)
+        def date = dateFormat.parse(dateStr)
+                
+        println("       String to Date with DateFormatter : " + date)
+
+        def cal = new GregorianCalendar();
+        cal.setTime(date);
+
+        assertEquals(cal.get(Calendar.YEAR),2019)
+        assertEquals(cal.get(Calendar.DAY_OF_MONTH),28)
+        assertEquals(cal.get(Calendar.MONTH),java.util.Calendar.FEBRUARY)
+    }
+
+    @Test
+    void whenGetStringRepresentation_thenCorrectlyConvertWithDateUtilsExtension() {
+    
+        def date = Date.parse(pattern, dateStr)
+                
+        println("       String to Date with Date.parse : " + date)
+    
+        def cal = new GregorianCalendar();
+        cal.setTime(date);
+
+        assertEquals(cal.get(Calendar.YEAR),2019)
+        assertEquals(cal.get(Calendar.DAY_OF_MONTH),28)
+        assertEquals(cal.get(Calendar.MONTH),java.util.Calendar.FEBRUARY)
+    }    
+
+    @Test
+    void whenGetStringRepresentation_thenCorrectlyConvertIntoDateWithLocalDate() {
+        def date = LocalDate.parse(dateStr, pattern)
+
+        println("       String to Date with LocalDate     : " + date)
+
+        assertEquals(date.getYear(),2019)
+        assertEquals(date.getMonth(),java.time.Month.FEBRUARY)
+        assertEquals(date.getDayOfMonth(),28)
+    }
+
+
+}

core-groovy/src/test/groovy/com/baeldung/file/ReadFileUnitTest.groovy

@@ -0,0 +1,70 @@
+package com.baeldung.file
+
+import spock.lang.Specification
+
+class ReadFileUnitTest extends Specification {
+
+    ReadFile readFile
+
+    void setup () {
+        readFile = new ReadFile()
+    }
+
+    def 'Should return number of lines in File using ReadFile.readFileLineByLine given filePath' () {
+        given:
+            def filePath = "src/main/resources/fileContent.txt"
+        when:
+            def noOfLines = readFile.readFileLineByLine(filePath)
+        then:
+            noOfLines
+            noOfLines instanceof Integer
+            assert noOfLines, 3
+    }
+    
+    def 'Should return File Content in list of lines using ReadFile.readFileInList given filePath' () {
+        given:
+            def filePath = "src/main/resources/fileContent.txt"
+        when:
+            def lines = readFile.readFileInList(filePath)
+        then:
+            lines
+            lines instanceof List<String>
+            assert lines.size(), 3
+    }
+    
+    def 'Should return file content in string using ReadFile.readFileString given filePath' () {
+        given:
+            def filePath = "src/main/resources/fileContent.txt"
+        when:
+            def fileContent = readFile.readFileString(filePath)
+        then:
+            fileContent
+            fileContent instanceof String
+            fileContent.contains("""Line 1 : Hello World!!!
+Line 2 : This is a file content.
+Line 3 : String content""")
+    
+    }
+
+    def 'Should return UTF-8 encoded file content in string using ReadFile.readFileStringWithCharset given filePath' () {
+        given:
+            def filePath = "src/main/resources/utf8Content.html"
+        when:
+            def encodedContent = readFile.readFileStringWithCharset(filePath)
+        then:
+            encodedContent
+            encodedContent instanceof String
+    }
+    
+    def 'Should return binary file content in byte array using ReadFile.readBinaryFile given filePath' () {
+        given:
+            def filePath = "src/main/resources/sample.png"
+        when:
+            def binaryContent = readFile.readBinaryFile(filePath)
+        then:
+            binaryContent
+            binaryContent instanceof byte[]
+            binaryContent.length == 329
+    }
+    
+}

core-groovy/src/test/groovy/com/baeldung/io/DataAndObjectsUnitTest.groovy

@@ -0,0 +1,51 @@
+package com.baeldung.io
+
+import static org.junit.Assert.*
+
+import org.junit.Test
+
+class DataAndObjectsUnitTest {
+    @Test
+    void whenUsingWithDataOutputStream_thenDataIsSerializedToAFile() {
+        String message = 'This is a serialized string'
+        int length = message.length()
+        boolean valid = true
+        new File('src/main/resources/ioData.txt').withDataOutputStream { out ->
+            out.writeUTF(message)
+            out.writeInt(length)
+            out.writeBoolean(valid)
+        }
+
+        String loadedMessage = ""
+        int loadedLength
+        boolean loadedValid
+        
+        new File('src/main/resources/ioData.txt').withDataInputStream { is ->
+            loadedMessage = is.readUTF()
+            loadedLength = is.readInt()
+            loadedValid = is.readBoolean()
+        }
+        
+        assertEquals(message, loadedMessage)
+        assertEquals(length, loadedLength)
+        assertEquals(valid, loadedValid)
+    }
+
+    @Test
+    void whenUsingWithObjectOutputStream_thenObjectIsSerializedToFile() {
+        Task task = new Task(description:'Take out the trash', startDate:new Date(), status:0)
+        new File('src/main/resources/ioSerializedObject.txt').withObjectOutputStream { out ->
+            out.writeObject(task)
+        }
+
+        Task taskRead
+        
+        new File('src/main/resources/ioSerializedObject.txt').withObjectInputStream { is ->
+            taskRead = is.readObject()
+        }
+        
+        assertEquals(task.description, taskRead.description)
+        assertEquals(task.startDate, taskRead.startDate)
+        assertEquals(task.status, taskRead.status)
+    }
+}

core-groovy/src/test/groovy/com/baeldung/io/ReadExampleUnitTest.groovy

@@ -0,0 +1,134 @@
+package com.baeldung.io
+
+import static org.junit.Assert.*
+import org.junit.Test
+
+class ReadExampleUnitTest {
+
+    @Test
+    void whenUsingEachLine_thenCorrectLinesReturned() {
+        def expectedList = [
+            'First line of text', 
+            'Second line of text', 
+            'Third line of text', 
+            'Fourth line of text']
+
+        def lines = []
+
+        new File('src/main/resources/ioInput.txt').eachLine { line ->
+            lines.add(line)
+        }
+        assertEquals(expectedList, lines)
+    }
+
+    @Test
+    void whenUsingReadEachLineWithLineNumber_thenCorrectLinesReturned() {
+        def expectedList = [
+            'Second line of text', 
+            'Third line of text', 
+            'Fourth line of text']
+
+        def lineNoRange = 2..4
+        def lines = []
+
+        new File('src/main/resources/ioInput.txt').eachLine { line, lineNo ->
+            if (lineNoRange.contains(lineNo)) {
+                lines.add(line)
+            }
+        }
+        assertEquals(expectedList, lines)
+    }
+    
+    @Test
+    void whenUsingReadEachLineWithLineNumberStartAtZero_thenCorrectLinesReturned() {
+        def expectedList = [
+            'Second line of text',
+            'Third line of text',
+            'Fourth line of text']
+
+        def lineNoRange = 1..3
+        def lines = []
+
+        new File('src/main/resources/ioInput.txt').eachLine(0, { line, lineNo ->
+            if (lineNoRange.contains(lineNo)) {
+                lines.add(line)
+            }
+        })
+        assertEquals(expectedList, lines)
+    }
+
+    @Test
+    void whenUsingWithReader_thenLineCountReturned() {
+        def expectedCount = 4
+        def actualCount = 0
+        new File('src/main/resources/ioInput.txt').withReader { reader ->
+            while(reader.readLine()) {
+                actualCount++
+            }
+        }
+        assertEquals(expectedCount, actualCount)
+    }
+
+    @Test
+    void whenUsingNewReader_thenOutputFileCreated() {
+        def outputPath = 'src/main/resources/ioOut.txt'
+        def reader = new File('src/main/resources/ioInput.txt').newReader()
+        new File(outputPath).append(reader)
+        reader.close()
+        def ioOut = new File(outputPath)
+        assertTrue(ioOut.exists())
+        ioOut.delete()
+    }
+
+    @Test
+    void whenUsingWithInputStream_thenCorrectBytesAreReturned() {
+        def expectedLength = 1139
+        byte[] data = []
+        new File("src/main/resources/binaryExample.jpg").withInputStream { stream ->
+            data = stream.getBytes()
+        }
+        assertEquals(expectedLength, data.length)
+    }
+
+    @Test
+    void whenUsingNewInputStream_thenOutputFileCreated() {
+        def outputPath = 'src/main/resources/binaryOut.jpg'
+        def is = new File('src/main/resources/binaryExample.jpg').newInputStream()
+        new File(outputPath).append(is)
+        is.close()
+        def ioOut = new File(outputPath)
+        assertTrue(ioOut.exists())
+        ioOut.delete()
+    }
+
+    @Test
+    void whenUsingCollect_thenCorrectListIsReturned() {
+        def expectedList = ['First line of text', 'Second line of text', 'Third line of text', 'Fourth line of text']
+
+        def actualList = new File('src/main/resources/ioInput.txt').collect {it}
+        assertEquals(expectedList, actualList)
+    }
+
+    @Test
+    void whenUsingAsStringArray_thenCorrectArrayIsReturned() {
+        String[] expectedArray = ['First line of text', 'Second line of text', 'Third line of text', 'Fourth line of text']
+
+        def actualArray = new File('src/main/resources/ioInput.txt') as String[]
+        assertArrayEquals(expectedArray, actualArray)
+    }
+
+    @Test
+    void whenUsingText_thenCorrectStringIsReturned() {
+        def ln = System.getProperty('line.separator')
+        def expectedString = "First line of text${ln}Second line of text${ln}Third line of text${ln}Fourth line of text"
+        def actualString = new File('src/main/resources/ioInput.txt').text
+        assertEquals(expectedString.toString(), actualString)
+    }
+
+    @Test
+    void whenUsingBytes_thenByteArrayIsReturned() {
+        def expectedLength = 1139
+        def contents = new File('src/main/resources/binaryExample.jpg').bytes
+        assertEquals(expectedLength, contents.length)
+    }
+}

core-groovy/src/test/groovy/com/baeldung/io/TraverseFileTreeUnitTest.groovy

@@ -0,0 +1,61 @@
+package com.baeldung.io
+
+import org.junit.Test
+
+import groovy.io.FileType
+import groovy.io.FileVisitResult
+
+class TraverseFileTreeUnitTest {
+    @Test
+    void whenUsingEachFile_filesAreListed() {
+        new File('src/main/resources').eachFile { file ->
+            println file.name
+        }
+    }
+    
+    @Test(expected = IllegalArgumentException)
+    void whenUsingEachFileOnAFile_anErrorOccurs() {
+        new File('src/main/resources/ioInput.txt').eachFile { file ->
+            println file.name
+        }
+    }
+    
+    @Test
+    void whenUsingEachFileMatch_filesAreListed() {
+        new File('src/main/resources').eachFileMatch(~/io.*\.txt/) { file ->
+            println file.name
+        }
+    }
+    
+    @Test
+    void whenUsingEachFileRecurse_thenFilesInSubfoldersAreListed() {
+        new File('src/main').eachFileRecurse(FileType.FILES) { file ->
+            println "$file.parent $file.name"
+        }
+    }
+    
+    @Test
+    void whenUsingEachFileRecurse_thenDirsInSubfoldersAreListed() {
+        new File('src/main').eachFileRecurse(FileType.DIRECTORIES) { file ->
+            println "$file.parent $file.name"
+        }
+    }
+    
+    @Test
+    void whenUsingEachDirRecurse_thenDirsAndSubDirsAreListed() {
+        new File('src/main').eachDirRecurse { dir ->
+            println "$dir.parent $dir.name"
+        }
+    }
+    
+    @Test
+    void whenUsingTraverse_thenDirectoryIsTraversed() {
+        new File('src/main').traverse { file ->
+            if (file.directory && file.name == 'groovy') {
+                FileVisitResult.SKIP_SUBTREE
+            } else {
+                println "$file.parent - $file.name"
+            }
+        }
+    }
+}

core-groovy/src/test/groovy/com/baeldung/io/WriteExampleUnitTest.groovy

@@ -0,0 +1,96 @@
+package com.baeldung.io
+
+import static org.junit.Assert.*
+
+import org.junit.Before
+import org.junit.Test
+
+class WriteExampleUnitTest {
+    @Before
+    void clearOutputFile() {
+        new File('src/main/resources/ioOutput.txt').text = ''
+        new File('src/main/resources/ioBinaryOutput.bin').delete()
+    }
+    
+    @Test
+    void whenUsingWithWriter_thenFileCreated() {
+        def outputLines = [
+            'Line one of output example',
+            'Line two of output example',
+            'Line three of output example'
+        ]
+        
+        def outputFileName = 'src/main/resources/ioOutput.txt'
+        new File(outputFileName).withWriter { writer ->
+            outputLines.each { line ->
+                writer.writeLine line
+            }
+        }
+        def writtenLines = new File(outputFileName).collect {it}
+        assertEquals(outputLines, writtenLines)
+    }
+    
+    @Test
+    void whenUsingNewWriter_thenFileCreated() {
+        def outputLines = [
+            'Line one of output example',
+            'Line two of output example',
+            'Line three of output example'
+        ]
+        
+        def outputFileName = 'src/main/resources/ioOutput.txt'
+        def writer = new File(outputFileName).newWriter()
+        outputLines.forEach {line ->
+            writer.writeLine line
+        }
+        writer.flush()
+        writer.close()
+        
+        def writtenLines = new File(outputFileName).collect {it}
+        assertEquals(outputLines, writtenLines)
+    }
+    
+    @Test
+    void whenUsingDoubleLessThanOperator_thenFileCreated() {
+        def outputLines = [
+            'Line one of output example',
+            'Line two of output example',
+            'Line three of output example'
+        ]
+        
+        def ln = System.getProperty('line.separator')
+        def outputFileName = 'src/main/resources/ioOutput.txt'
+        new File(outputFileName) << "Line one of output example${ln}Line two of output example${ln}Line three of output example"
+        def writtenLines = new File(outputFileName).collect {it}
+        assertEquals(outputLines.size(), writtenLines.size())
+    }
+    
+    @Test
+    void whenUsingBytes_thenBinaryFileCreated() {
+        def outputFileName = 'src/main/resources/ioBinaryOutput.bin'
+        def outputFile = new File(outputFileName)
+        byte[] outBytes = [44, 88, 22]
+        outputFile.bytes = outBytes
+        assertEquals(3, new File(outputFileName).size())
+    }
+    
+    @Test
+    void whenUsingWithOutputStream_thenBinaryFileCreated() {
+        def outputFileName = 'src/main/resources/ioBinaryOutput.bin'
+        byte[] outBytes = [44, 88, 22]
+        new File(outputFileName).withOutputStream { stream ->
+            stream.write(outBytes)
+        }
+        assertEquals(3, new File(outputFileName).size())
+    }
+    
+    @Test
+    void whenUsingNewOutputStream_thenBinaryFileCreated() {
+        def outputFileName = 'src/main/resources/ioBinaryOutput.bin'
+        byte[] outBytes = [44, 88, 22]
+        def os = new File(outputFileName).newOutputStream()
+        os.write(outBytes)
+        os.close()
+        assertEquals(3, new File(outputFileName).size())
+    }
+}

core-groovy/src/test/groovy/com/baeldung/lists/ListTest.groovy

@@ -0,0 +1,173 @@
+package com.baeldung.groovy.lists
+
+import static groovy.test.GroovyAssert.*
+import org.junit.Test
+
+class ListTest{
+
+    @Test
+    void testCreateList() {
+
+        def list = [1, 2, 3]
+        assertNotNull(list)
+
+        def listMix = ['A', "b", 1, true]
+        assertTrue(listMix == ['A', "b", 1, true])
+
+        def linkedList = [1, 2, 3] as LinkedList
+        assertTrue(linkedList instanceof LinkedList)
+
+        ArrayList arrList = [1, 2, 3]
+        assertTrue(arrList.class == ArrayList)
+
+        def copyList = new ArrayList(arrList)
+        assertTrue(copyList == arrList)
+
+        def cloneList = arrList.clone()
+        assertTrue(cloneList == arrList)
+    }
+
+    @Test
+    void testCreateEmptyList() {
+
+        def emptyList = []
+        assertTrue(emptyList.size() == 0)
+    }
+
+    @Test
+    void testCompareTwoLists() {
+
+        def list1 = [5, 6.0, 'p']
+        def list2 = [5, 6.0, 'p']
+        assertTrue(list1 == list2)
+    }
+
+    @Test
+    void testGetItemsFromList(){
+
+        def list = ["Hello", "World"]
+
+        assertTrue(list.get(1) == "World")
+        assertTrue(list[1] == "World")
+        assertTrue(list[-1] == "World")
+        assertTrue(list.getAt(1) == "World")
+        assertTrue(list.getAt(-2) == "Hello")
+    }
+
+    @Test
+    void testAddItemsToList() {
+
+        def list = []
+
+        list << 1
+        list.add("Apple")
+        assertTrue(list == [1, "Apple"])
+
+        list[2] = "Box"
+        list[4] = true
+        assertTrue(list == [1, "Apple", "Box", null, true])
+
+        list.add(1, 6.0)
+        assertTrue(list == [1, 6.0, "Apple", "Box", null, true])
+
+        def list2 = [1, 2]
+        list += list2
+        list += 12
+        assertTrue(list == [1, 6.0, "Apple", "Box", null, true, 1, 2, 12])
+    }
+
+    @Test
+    void testUpdateItemsInList() {
+
+        def list =[1, "Apple", 80, "App"]
+        list[1] = "Box"
+        list.set(2,90)
+        assertTrue(list == [1, "Box", 90, "App"])
+    }
+
+    @Test
+    void testRemoveItemsFromList(){
+
+        def list = [1, 2, 3, 4, 5, 5, 6, 6, 7]
+
+        list.remove(3)
+        assertTrue(list == [1, 2, 3, 5, 5, 6, 6, 7])
+
+        list.removeElement(5)
+        assertTrue(list == [1, 2, 3, 5, 6, 6, 7])
+
+        assertTrue(list - 6 == [1, 2, 3, 5, 7])
+    }
+
+    @Test
+    void testIteratingOnAList(){
+
+        def list = [1, "App", 3, 4]
+        list.each{ println it * 2}
+
+        list.eachWithIndex{ it, i -> println "$i : $it" }
+    }
+
+    @Test
+    void testCollectingToAnotherList(){
+
+        def list = ["Kay", "Henry", "Justin", "Tom"]
+        assertTrue(list.collect{"Hi " + it} == ["Hi Kay", "Hi Henry", "Hi Justin", "Hi Tom"])
+    }
+
+    @Test
+    void testJoinItemsInAList(){
+        assertTrue(["One", "Two", "Three"].join(",") == "One,Two,Three")
+    }
+
+    @Test
+    void testFilteringOnLists(){
+        def filterList = [2, 1, 3, 4, 5, 6, 76]
+
+        assertTrue(filterList.find{it > 3} == 4)
+
+        assertTrue(filterList.findAll{it > 3} == [4, 5, 6, 76])
+
+        assertTrue(filterList.findAll{ it instanceof Number} == [2, 1, 3, 4, 5, 6, 76])
+        
+        assertTrue(filterList.grep( Number )== [2, 1, 3, 4, 5, 6, 76])
+        
+        assertTrue(filterList.grep{ it> 6 }== [76])
+
+        def conditionList = [2, 1, 3, 4, 5, 6, 76]
+        
+        assertFalse(conditionList.every{ it < 6})
+
+        assertTrue(conditionList.any{ it%2 == 0})
+
+    }
+
+    @Test
+    void testGetUniqueItemsInAList(){
+        assertTrue([1, 3, 3, 4].toUnique() == [1, 3, 4])
+
+        def uniqueList = [1, 3, 3, 4]
+        uniqueList.unique()
+        assertTrue(uniqueList == [1, 3, 4])
+
+        assertTrue(["A", "B", "Ba", "Bat", "Cat"].toUnique{ it.size()} == ["A", "Ba", "Bat"])
+    }
+
+    @Test
+    void testSorting(){
+
+        assertTrue([1, 2, 1, 0].sort() == [0, 1, 1, 2])
+        Comparator mc = {a,b -> a == b? 0: a < b? 1 : -1}
+
+        def list = [1, 2, 1, 0]
+        list.sort(mc)
+        assertTrue(list == [2, 1, 1, 0])
+
+        def strList = ["na", "ppp", "as"]
+        assertTrue(strList.max() == "ppp")
+        
+        Comparator minc = {a,b -> a == b? 0: a < b? -1 : 1}
+        def numberList = [3, 2, 0, 7]
+        assertTrue(numberList.min(minc) == 0)
+    }
+}

core-groovy/src/test/groovy/com/baeldung/map/MapUnitTest.groovy

@@ -0,0 +1,85 @@
+package com.baeldung.map
+
+import static org.junit.Assert.*
+import org.junit.Test
+
+class MapUnitTest {
+
+    @Test
+    void whenUsingEach_thenMapIsIterated() {
+        def map = [
+            'FF0000' : 'Red',
+            '00FF00' : 'Lime',
+            '0000FF' : 'Blue',
+            'FFFF00' : 'Yellow'
+        ]
+
+        map.each { println "Hex Code: $it.key = Color Name: $it.value" }
+    }
+
+    @Test
+    void whenUsingEachWithEntry_thenMapIsIterated() {
+        def map = [
+            'E6E6FA' : 'Lavender',
+            'D8BFD8' : 'Thistle',
+            'DDA0DD' : 'Plum',
+        ]
+
+        map.each { entry -> println "Hex Code: $entry.key = Color Name: $entry.value" }
+    }
+
+    @Test
+    void whenUsingEachWithKeyAndValue_thenMapIsIterated() {
+        def map = [
+            '000000' : 'Black',
+            'FFFFFF' : 'White',
+            '808080' : 'Gray'
+        ]
+
+        map.each { key, val ->
+            println "Hex Code: $key = Color Name $val"
+        }
+    }
+
+    @Test
+    void whenUsingEachWithIndexAndEntry_thenMapIsIterated() {
+        def map = [
+            '800080' : 'Purple',
+            '4B0082' : 'Indigo',
+            '6A5ACD' : 'Slate Blue'
+        ]
+
+        map.eachWithIndex { entry, index ->
+            def indent = ((index == 0 || index % 2 == 0) ? "   " : "")
+            println "$indent Hex Code: $entry.key = Color Name: $entry.value"
+        }
+    }
+
+    @Test
+    void whenUsingEachWithIndexAndKeyAndValue_thenMapIsIterated() {
+        def map = [
+            'FFA07A' : 'Light Salmon',
+            'FF7F50' : 'Coral',
+            'FF6347' : 'Tomato',
+            'FF4500' : 'Orange Red'
+        ]
+        
+        map.eachWithIndex { key, val, index ->
+            def indent = ((index == 0 || index % 2 == 0) ? "   " : "")
+            println "$indent Hex Code: $key = Color Name: $val"
+        }
+    }
+
+    @Test
+    void whenUsingForLoop_thenMapIsIterated() {
+        def map = [
+            '2E8B57' : 'Seagreen',
+            '228B22' : 'Forest Green',
+            '008000' : 'Green'
+        ]
+
+        for (entry in map) {
+            println "Hex Code: $entry.key = Color Name: $entry.value"
+        }
+    }
+}

core-groovy/src/test/groovy/com/baeldung/strings/ConcatenateTest.groovy

@@ -0,0 +1,101 @@
+import com.baeldung.strings.Concatenate;
+
+class ConcatenateTest extends GroovyTestCase {
+    
+    void testSimpleConcat() {
+        def name = new Concatenate()
+        name.first = 'Joe';
+        name.last = 'Smith';
+        def expected = 'My name is Joe Smith'
+        assertToString(name.doSimpleConcat(), expected)
+    }
+    
+    void testConcatUsingGString() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingGString(), expected)
+    }
+    
+    void testConcatUsingGStringClosures() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingGStringClosures(), expected)
+    }
+    
+    void testConcatUsingStringConcatMethod() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingStringConcatMethod(), expected)
+    }
+
+    void testConcatUsingLeftShiftOperator() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingLeftShiftOperator(), expected)
+    }
+
+    void testConcatUsingArrayJoinMethod() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingArrayJoinMethod(), expected)
+    }
+
+    void testConcatUsingArrayInjectMethod() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingArrayInjectMethod(), expected)
+    }
+
+    void testConcatUsingStringBuilder() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingStringBuilder(), expected)
+    }
+
+    void testConcatUsingStringBuffer() {
+        def name = new Concatenate()
+        name.first = "Joe";
+        name.last = "Smith";
+        def expected = "My name is Joe Smith"
+        assertToString(name.doConcatUsingStringBuffer(), expected)
+    }
+
+    void testConcatMultilineUsingStringConcatMethod() {
+        def name = new Concatenate()
+        name.first = '''Joe
+                        Smith
+                        ''';
+        name.last = 'Junior';
+        def expected = '''My name is Joe
+                        Smith
+                         Junior''';
+        assertToString(name.doConcatUsingStringConcatMethod(), expected)
+    }
+
+    void testGStringvsClosure(){
+        def first = "Joe";
+        def last = "Smith";
+        def eagerGString = "My name is $first $last"
+        def lazyGString = "My name is ${-> first} ${-> last}"
+
+        assert eagerGString == "My name is Joe Smith"
+        assert lazyGString == "My name is Joe Smith"
+        first = "David";
+        assert eagerGString == "My name is Joe Smith"
+        assert lazyGString == "My name is David Smith"
+    }  
+}

core-groovy/src/test/groovy/com/baeldung/stringtypes/CharacterInGroovy.groovy

@@ -0,0 +1,19 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Assert
+import org.junit.Test
+
+class CharacterInGroovy {
+
+    @Test
+    void 'character'() {
+        char a = 'A' as char
+        char b = 'B' as char
+        char c = (char) 'C'
+
+        Assert.assertTrue(a instanceof Character)
+        Assert.assertTrue(b instanceof Character)
+        Assert.assertTrue(c instanceof Character)
+    }
+
+}

core-groovy/src/test/groovy/com/baeldung/stringtypes/DollarSlashyString.groovy

@@ -0,0 +1,24 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Test
+
+class DollarSlashyString {
+
+    @Test
+    void 'dollar slashy string'() {
+        def name = "John"
+
+        def dollarSlashy = $/
+            Hello $name!,
+
+            I can show you $ sign or escaped dollar sign: $$ 
+            Both slashes works: \ or /, but we can still escape it: $/
+            
+            We have to escape opening and closing delimiter:
+            - $$$/  
+            - $/$$
+        /$
+
+        print(dollarSlashy)
+    }
+}

core-groovy/src/test/groovy/com/baeldung/stringtypes/DoubleQuotedString.groovy

@@ -0,0 +1,67 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Assert
+import org.junit.Test
+
+class DoubleQuotedString {
+
+    @Test
+    void 'escape double quoted string'() {
+        def example = "Hello \"world\"!"
+
+        println(example)
+    }
+
+    @Test
+    void 'String ang GString'() {
+        def string = "example"
+        def stringWithExpression = "example${2}"
+
+        Assert.assertTrue(string instanceof String)
+        Assert.assertTrue(stringWithExpression instanceof GString)
+        Assert.assertTrue(stringWithExpression.toString() instanceof String)
+    }
+
+    @Test
+    void 'placeholder with variable'() {
+        def name = "John"
+        def helloName = "Hello $name!".toString()
+
+        Assert.assertEquals("Hello John!", helloName)
+    }
+
+    @Test
+    void 'placeholder with expression'() {
+        def result = "result is ${2 * 2}".toString()
+
+        Assert.assertEquals("result is 4", result)
+    }
+
+    @Test
+    void 'placeholder with dotted access'() {
+        def person = [name: 'John']
+
+        def myNameIs = "I'm $person.name, and you?".toString()
+
+        Assert.assertEquals("I'm John, and you?", myNameIs)
+    }
+
+    @Test
+    void 'placeholder with method call'() {
+        def name = 'John'
+
+        def result = "Uppercase name: ${name.toUpperCase()}".toString()
+
+        Assert.assertEquals("Uppercase name: JOHN", result)
+    }
+
+
+    @Test
+    void 'GString and String hashcode'() {
+        def string = "2+2 is 4"
+        def gstring = "2+2 is ${4}"
+
+        Assert.assertTrue(string.hashCode() != gstring.hashCode())
+    }
+
+}

core-groovy/src/test/groovy/com/baeldung/stringtypes/SingleQuotedString.groovy

@@ -0,0 +1,15 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Assert
+import org.junit.Test
+
+class SingleQuotedString {
+
+    @Test
+    void 'single quoted string'() {
+        def example = 'Hello world'
+
+        Assert.assertEquals('Hello world!', 'Hello' + ' world!')
+    }
+
+}

core-groovy/src/test/groovy/com/baeldung/stringtypes/SlashyString.groovy

@@ -0,0 +1,31 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Assert
+import org.junit.Test
+
+class SlashyString {
+
+    @Test
+    void 'slashy string'() {
+        def pattern = /.*foobar.*\/hello.*/
+
+        Assert.assertTrue("I'm matching foobar /hello regexp pattern".matches(pattern))
+    }
+
+    void 'wont compile'() {
+//        if ('' == //) {
+//            println("I can't compile")
+//        }
+    }
+
+    @Test
+    void 'interpolate and multiline'() {
+        def name = 'John'
+
+        def example = /
+            Hello $name
+            second line        
+        /
+    }
+
+}

core-groovy/src/test/groovy/com/baeldung/stringtypes/Strings.groovy

@@ -0,0 +1,26 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Assert
+import org.junit.Test
+
+class Strings {
+
+    @Test
+    void 'string interpolation '() {
+        def name = "Kacper"
+
+        def result = "Hello ${name}!"
+
+        Assert.assertEquals("Hello Kacper!", result.toString())
+    }
+
+    @Test
+    void 'string concatenation'() {
+        def first = "first"
+        def second = "second"
+
+        def concatenation = first + second
+
+        Assert.assertEquals("firstsecond", concatenation)
+    }
+}

core-groovy/src/test/groovy/com/baeldung/stringtypes/TripleDoubleQuotedString.groovy

@@ -0,0 +1,19 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Test
+
+class TripleDoubleQuotedString {
+
+    @Test
+    void 'triple-quoted strings with interpolation'() {
+        def name = "John"
+
+        def multiLine = """
+            I'm $name.
+            "This is quotation"
+        """
+
+        println(multiLine)
+    }
+
+}

core-groovy/src/test/groovy/com/baeldung/stringtypes/TripleSingleQuotedString.groovy

@@ -0,0 +1,67 @@
+package groovy.com.baeldung.stringtypes
+
+import org.junit.Assert
+import org.junit.Test
+
+class TripleSingleQuotedString {
+
+    def 'formatted json'() {
+        def jsonContent = '''
+        {
+            "name": "John",
+            "age": 20,
+            "birthDate": null
+        }
+        '''
+    }
+
+    def 'triple single quoted'() {
+        def triple = '''im triple single quoted string'''
+    }
+
+    @Test
+    void 'triple single quoted with multiline string'() {
+        def triple = '''
+            firstline
+            secondline
+        '''
+
+        Assert.assertTrue(triple.startsWith("\n"))
+    }
+
+    @Test
+    void 'triple single quoted with multiline string with stripIndent() and removing newline characters'() {
+        def triple = '''\
+            firstline
+            secondline'''.stripIndent()
+
+        Assert.assertEquals("firstline\nsecondline", triple)
+    }
+
+    @Test
+    void 'triple single quoted with multiline string with last line with only whitespaces'() {
+        def triple = '''\
+            firstline
+                secondline\
+        '''.stripIndent()
+
+        println(triple)
+    }
+
+    @Test
+    void 'triple single quoted with multiline string with stripMargin(Character) and removing newline characters'() {
+        def triple = '''\
+            |firstline
+            |secondline'''.stripMargin()
+
+        println(triple)
+    }
+
+    @Test
+    void 'striple single quoted with special characters'() {
+        def specialCharacters = '''hello \'John\'. This is backslash - \\. \nSecond line starts here'''
+
+        println(specialCharacters)
+    }
+
+}

core-groovy/src/test/groovy/com/baeldung/traits/TraitsUnitTest.groovy

@@ -0,0 +1,114 @@
+package com.baeldung.traits
+
+import spock.lang.Specification
+
+class TraitsUnitTest extends Specification {
+
+    Employee employee
+    Dog dog
+
+    void setup () {
+        employee = new Employee()
+        dog = new Dog()
+    }
+
+    def 'Should return msg string when using Employee.sayHello method provided by UserTrait' () {
+        when:
+            def msg = employee.sayHello()
+        then:
+            msg
+            msg instanceof String
+            assert msg == "Hello!"
+    }
+    
+    def 'Should return displayMsg string when using Employee.showName method' () {
+        when:
+            def displayMsg = employee.showName()
+        then:
+            displayMsg
+            displayMsg instanceof String
+            assert displayMsg == "Hello, Bob!"
+    }
+    
+    def 'Should return greetMsg string when using Employee.greet method' () {
+        when:
+            def greetMsg = employee.greet()
+        then:
+            greetMsg
+            greetMsg instanceof String
+            assert greetMsg == "Hello, from a private method!"
+    }
+    
+    def 'Should return MissingMethodException when using Employee.greetingMessage method' () {
+        when:
+            def exception
+            try {
+                employee.greetingMessage()
+            }catch(Exception e) {
+                exception = e
+            }
+            
+        then:
+            exception
+            exception instanceof groovy.lang.MissingMethodException
+            assert exception.message == "No signature of method: com.baeldung.traits.Employee.greetingMessage()"+
+            " is applicable for argument types: () values: []"
+    }
+    
+    def 'Should return employee instance when using Employee.whoAmI method' () {
+        when:
+            def emp = employee.self()
+        then:
+            emp
+            emp instanceof Employee
+            assert emp.is(employee)
+    }
+    
+    def 'Should display lastName when using Employee.showLastName method' () {
+        when:
+            def lastNameMsg = employee.showLastName()
+        then:
+            lastNameMsg
+            lastNameMsg instanceof String
+            assert lastNameMsg == "Hello, Marley!"
+    }
+    
+    def 'Should be able to define properties of UserTrait in Employee instance' () {
+        when:
+            employee = new Employee(email: "a@e.com", address: "baeldung.com")
+        then:
+            employee
+            employee instanceof Employee
+            assert employee.email == "a@e.com"
+            assert employee.address == "baeldung.com"
+    }
+    
+    def 'Should execute basicAbility method from SpeakingTrait and return msg string' () {
+        when:
+            def speakMsg = dog.basicAbility()
+        then:
+            speakMsg
+            speakMsg instanceof String
+            assert speakMsg == "Speaking!!"
+    }
+    
+    def 'Should verify multiple inheritance with traits and execute overridden traits method' () {
+        when:
+            def walkSpeakMsg = dog.speakAndWalk()
+            println walkSpeakMsg
+        then:
+            walkSpeakMsg
+            walkSpeakMsg instanceof String
+            assert walkSpeakMsg == "Walk and speak!!"
+    }
+    
+    def 'Should implement AnimalTrait at runtime and access basicBehavior method' () {
+        when:
+            def dogInstance = new Dog() as AnimalTrait
+            def basicBehaviorMsg = dogInstance.basicBehavior()
+        then:
+            basicBehaviorMsg
+            basicBehaviorMsg instanceof String
+            assert basicBehaviorMsg == "Animalistic!!"
+    }
+}

core-java-10/pom.xml

@@ -3,9 +3,9 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.baeldung</groupId>
     <artifactId>core-java-10</artifactId>
-    <packaging>jar</packaging>
     <version>0.1.0-SNAPSHOT</version>
     <name>core-java-10</name>
+    <packaging>jar</packaging>
     <url>http://maven.apache.org</url>
 
     <parent>

core-java-11/README.md

@@ -3,3 +3,4 @@
 - [Java 11 Single File Source Code](https://www.baeldung.com/java-single-file-source-code)
 - [Java 11 Local Variable Syntax for Lambda Parameters](https://www.baeldung.com/java-var-lambda-params)
 - [Java 11 String API Additions](https://www.baeldung.com/java-11-string-api)
+- [Java 11 Nest Based Access Control](https://www.baeldung.com/java-nest-based-access-control)

core-java-11/pom.xml

@@ -3,9 +3,9 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.baeldung</groupId>
     <artifactId>core-java-11</artifactId>
-    <packaging>jar</packaging>
     <version>0.1.0-SNAPSHOT</version>
     <name>core-java-11</name>
+    <packaging>jar</packaging>
     <url>http://maven.apache.org</url>
 
     <parent>

core-java-11/src/main/java/com/baeldung/epsilongc/MemoryPolluter.java

@@ -0,0 +1,18 @@
+package com.baeldung.epsilongc;
+
+public class MemoryPolluter {
+
+    private static final int MEGABYTE_IN_BYTES = 1024 * 1024;
+    private static final int ITERATION_COUNT = 1024 * 10;
+
+    public static void main(String[] args) {
+        System.out.println("Starting pollution");
+
+        for (int i = 0; i < ITERATION_COUNT; i++) {
+            byte[] array = new byte[MEGABYTE_IN_BYTES];
+        }
+
+        System.out.println("Terminating");
+    }
+
+}

core-java-11/src/main/java/com/baeldung/java11/httpclient/HttpClientExample.java

@@ -0,0 +1,132 @@
+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package com.baeldung.java11.httpclient;
+
+import java.io.IOException;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpClient.Version;
+import java.net.http.HttpRequest;
+import java.net.http.HttpRequest.BodyPublishers;
+import java.net.http.HttpResponse;
+import java.net.http.HttpResponse.BodyHandlers;
+import java.net.http.HttpResponse.PushPromiseHandler;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+public class HttpClientExample {
+
+    public static void main(String[] args) throws Exception {
+        httpGetRequest();
+        httpPostRequest();
+        asynchronousGetRequest();
+        asynchronousMultipleRequests();
+        pushRequest();
+    }
+
+    public static void httpGetRequest() throws URISyntaxException, IOException, InterruptedException {
+        HttpClient client = HttpClient.newHttpClient();
+        HttpRequest request = HttpRequest.newBuilder()
+            .version(HttpClient.Version.HTTP_2)
+            .uri(URI.create("http://jsonplaceholder.typicode.com/posts/1"))
+            .headers("Accept-Enconding", "gzip, deflate")
+            .build();
+        HttpResponse<String> response = client.send(request, BodyHandlers.ofString());
+
+        String responseBody = response.body();
+        int responseStatusCode = response.statusCode();
+
+        System.out.println("httpGetRequest: " + responseBody);
+        System.out.println("httpGetRequest status code: " + responseStatusCode);
+    }
+
+    public static void httpPostRequest() throws URISyntaxException, IOException, InterruptedException {
+        HttpClient client = HttpClient.newBuilder()
+            .version(HttpClient.Version.HTTP_2)
+            .build();
+        HttpRequest request = HttpRequest.newBuilder(new URI("http://jsonplaceholder.typicode.com/posts"))
+            .version(HttpClient.Version.HTTP_2)
+            .POST(BodyPublishers.ofString("Sample Post Request"))
+            .build();
+        HttpResponse<String> response = client.send(request, BodyHandlers.ofString());
+        String responseBody = response.body();
+        System.out.println("httpPostRequest : " + responseBody);
+    }
+
+    public static void asynchronousGetRequest() throws URISyntaxException {
+        HttpClient client = HttpClient.newHttpClient();
+        URI httpURI = new URI("http://jsonplaceholder.typicode.com/posts/1");
+        HttpRequest request = HttpRequest.newBuilder(httpURI)
+            .version(HttpClient.Version.HTTP_2)
+            .build();
+        CompletableFuture<Void> futureResponse = client.sendAsync(request, HttpResponse.BodyHandlers.ofString())
+            .thenAccept(resp -> {
+                System.out.println("Got pushed response " + resp.uri());
+                System.out.println("Response statuscode: " + resp.statusCode());
+                System.out.println("Response body: " + resp.body());
+            });
+        System.out.println("futureResponse" + futureResponse);
+
+    }
+
+    public static void asynchronousMultipleRequests() throws URISyntaxException {
+        HttpClient client = HttpClient.newHttpClient();
+        List<URI> uris = Arrays.asList(new URI("http://jsonplaceholder.typicode.com/posts/1"), new URI("http://jsonplaceholder.typicode.com/posts/2"));
+        List<HttpRequest> requests = uris.stream()
+            .map(HttpRequest::newBuilder)
+            .map(reqBuilder -> reqBuilder.build())
+            .collect(Collectors.toList());
+        System.out.println("Got pushed response1 " + requests);
+        CompletableFuture.allOf(requests.stream()
+            .map(request -> client.sendAsync(request, BodyHandlers.ofString()))
+            .toArray(CompletableFuture<?>[]::new))
+            .thenAccept(System.out::println)
+            .join();
+    }
+
+    public static void pushRequest() throws URISyntaxException, InterruptedException {
+        System.out.println("Running HTTP/2 Server Push example...");
+
+        HttpClient httpClient = HttpClient.newBuilder()
+            .version(Version.HTTP_2)
+            .build();
+
+        HttpRequest pageRequest = HttpRequest.newBuilder()
+            .uri(URI.create("https://http2.golang.org/serverpush"))
+            .build();
+
+        // Interface HttpResponse.PushPromiseHandler<T>
+        // void applyPushPromise​(HttpRequest initiatingRequest, HttpRequest pushPromiseRequest, Function<HttpResponse.BodyHandler<T>,​CompletableFuture<HttpResponse<T>>> acceptor)
+        httpClient.sendAsync(pageRequest, BodyHandlers.ofString(), pushPromiseHandler())
+            .thenAccept(pageResponse -> {
+                System.out.println("Page response status code: " + pageResponse.statusCode());
+                System.out.println("Page response headers: " + pageResponse.headers());
+                String responseBody = pageResponse.body();
+                System.out.println(responseBody);
+            }).join();
+
+        Thread.sleep(1000); // waiting for full response
+    }
+
+    private static PushPromiseHandler<String> pushPromiseHandler() {
+        return (HttpRequest initiatingRequest, 
+            HttpRequest pushPromiseRequest, 
+            Function<HttpResponse.BodyHandler<String>, 
+            CompletableFuture<HttpResponse<String>>> acceptor) -> {
+            acceptor.apply(BodyHandlers.ofString())
+                .thenAccept(resp -> {
+                    System.out.println(" Pushed response: " + resp.uri() + ", headers: " + resp.headers());
+                });
+            System.out.println("Promise request: " + pushPromiseRequest.uri());
+            System.out.println("Promise request: " + pushPromiseRequest.headers());
+        };
+    }
+
+}

core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpClientTest.java

@@ -0,0 +1,240 @@
+package com.baeldung.java11.httpclient.test;
+
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import java.io.IOException;
+import java.net.Authenticator;
+import java.net.CookieManager;
+import java.net.CookiePolicy;
+import java.net.HttpURLConnection;
+import java.net.PasswordAuthentication;
+import java.net.ProxySelector;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.net.http.HttpResponse.BodyHandlers;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionException;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Collectors;
+
+import org.junit.jupiter.api.Test;
+
+public class HttpClientTest {
+
+    @Test
+    public void shouldReturnSampleDataContentWhenConnectViaSystemProxy() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .headers("Content-Type", "text/plain;charset=UTF-8")
+            .POST(HttpRequest.BodyPublishers.ofString("Sample body"))
+            .build();
+      
+        
+        HttpResponse<String> response = HttpClient.newBuilder()
+            .proxy(ProxySelector.getDefault())
+            .build()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+        
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.body(), containsString("Sample body"));
+    }
+
+    @Test
+    public void shouldNotFollowRedirectWhenSetToDefaultNever() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("http://stackoverflow.com"))
+            .version(HttpClient.Version.HTTP_1_1)
+            .GET()
+            .build();
+        HttpResponse<String> response = HttpClient.newBuilder()
+            .build()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_MOVED_PERM));
+        assertThat(response.body(), containsString("https://stackoverflow.com/"));
+    }
+
+    @Test
+    public void shouldFollowRedirectWhenSetToAlways() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("http://stackoverflow.com"))
+            .version(HttpClient.Version.HTTP_1_1)
+            .GET()
+            .build();
+        HttpResponse<String> response = HttpClient.newBuilder()
+            .followRedirects(HttpClient.Redirect.ALWAYS)
+            .build()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.request()
+            .uri()
+            .toString(), equalTo("https://stackoverflow.com/"));
+    }
+
+    @Test
+    public void shouldReturnOKStatusForAuthenticatedAccess() throws URISyntaxException, IOException, InterruptedException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/basic-auth"))
+            .GET()
+            .build();
+        HttpResponse<String> response = HttpClient.newBuilder()
+            .authenticator(new Authenticator() {
+                @Override
+                protected PasswordAuthentication getPasswordAuthentication() {
+                    return new PasswordAuthentication("postman", "password".toCharArray());
+                }
+            })
+            .build()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldSendRequestAsync() throws URISyntaxException, InterruptedException, ExecutionException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .headers("Content-Type", "text/plain;charset=UTF-8")
+            .POST(HttpRequest.BodyPublishers.ofString("Sample body"))
+            .build();
+        CompletableFuture<HttpResponse<String>> response = HttpClient.newBuilder()
+            .build()
+            .sendAsync(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.get()
+            .statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldUseJustTwoThreadWhenProcessingSendAsyncRequest() throws URISyntaxException, InterruptedException, ExecutionException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .GET()
+            .build();
+
+        ExecutorService executorService = Executors.newFixedThreadPool(2);
+
+        CompletableFuture<HttpResponse<String>> response1 = HttpClient.newBuilder()
+            .executor(executorService)
+            .build()
+            .sendAsync(request, HttpResponse.BodyHandlers.ofString());
+
+        CompletableFuture<HttpResponse<String>> response2 = HttpClient.newBuilder()
+            .executor(executorService)
+            .build()
+            .sendAsync(request, HttpResponse.BodyHandlers.ofString());
+
+        CompletableFuture<HttpResponse<String>> response3 = HttpClient.newBuilder()
+            .executor(executorService)
+            .build()
+            .sendAsync(request, HttpResponse.BodyHandlers.ofString());
+
+        CompletableFuture.allOf(response1, response2, response3)
+            .join();
+
+        assertThat(response1.get()
+            .statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response2.get()
+            .statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response3.get()
+            .statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldNotStoreCookieWhenPolicyAcceptNone() throws URISyntaxException, IOException, InterruptedException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .GET()
+            .build();
+
+        HttpClient httpClient = HttpClient.newBuilder()
+            .cookieHandler(new CookieManager(null, CookiePolicy.ACCEPT_NONE))
+            .build();
+
+        httpClient.send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertTrue(httpClient.cookieHandler()
+            .isPresent());
+    }
+
+    @Test
+    public void shouldStoreCookieWhenPolicyAcceptAll() throws URISyntaxException, IOException, InterruptedException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .GET()
+            .build();
+
+        HttpClient httpClient = HttpClient.newBuilder()
+            .cookieHandler(new CookieManager(null, CookiePolicy.ACCEPT_ALL))
+            .build();
+
+        httpClient.send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertTrue(httpClient.cookieHandler()
+            .isPresent());
+    }
+
+    @Test
+    public void shouldProcessMultipleRequestViaStream() throws URISyntaxException, ExecutionException, InterruptedException {
+        List<URI> targets = Arrays.asList(new URI("https://postman-echo.com/get?foo1=bar1"), new URI("https://postman-echo.com/get?foo2=bar2"));
+
+        HttpClient client = HttpClient.newHttpClient();
+
+        List<CompletableFuture<String>> futures = targets.stream()
+            .map(target -> client.sendAsync(HttpRequest.newBuilder(target)
+                .GET()
+                .build(), HttpResponse.BodyHandlers.ofString())
+                .thenApply(response -> response.body()))
+            .collect(Collectors.toList());
+
+        CompletableFuture.allOf(futures.toArray(new CompletableFuture[0]))
+            .join();
+
+        if (futures.get(0)
+            .get()
+            .contains("foo1")) {
+            assertThat(futures.get(0)
+                .get(), containsString("bar1"));
+            assertThat(futures.get(1)
+                .get(), containsString("bar2"));
+        } else {
+            assertThat(futures.get(1)
+                .get(), containsString("bar2"));
+            assertThat(futures.get(1)
+                .get(), containsString("bar1"));
+        }
+
+    }
+    
+    @Test
+    public void completeExceptionallyExample() {
+        CompletableFuture<String> cf = CompletableFuture.completedFuture("message").thenApplyAsync(String::toUpperCase,
+                CompletableFuture.delayedExecutor(1, TimeUnit.SECONDS));
+        CompletableFuture<String> exceptionHandler = cf.handle((s, th) -> { return (th != null) ? "message upon cancel" : ""; });
+        cf.completeExceptionally(new RuntimeException("completed exceptionally"));
+        assertTrue("Was not completed exceptionally", cf.isCompletedExceptionally());
+        try {
+            cf.join();
+            fail("Should have thrown an exception");
+        } catch (CompletionException ex) { // just for testing
+            assertEquals("completed exceptionally", ex.getCause().getMessage());
+        }
+
+        assertEquals("message upon cancel", exceptionHandler.join());
+    }
+
+}

core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpRequestTest.java

@@ -0,0 +1,168 @@
+package com.baeldung.java11.httpclient.test;
+
+import static java.time.temporal.ChronoUnit.SECONDS;
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.junit.Assert.assertThat;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.nio.file.Paths;
+import java.security.NoSuchAlgorithmException;
+import java.time.Duration;
+
+import org.junit.Test;
+
+public class HttpRequestTest {
+
+    @Test
+    public void shouldReturnStatusOKWhenSendGetRequest() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .GET()
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldUseHttp2WhenWebsiteUsesHttp2() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://stackoverflow.com"))
+            .version(HttpClient.Version.HTTP_2)
+            .GET()
+            .build();
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.version(), equalTo(HttpClient.Version.HTTP_2));
+    }
+
+    @Test
+    public void shouldFallbackToHttp1_1WhenWebsiteDoesNotUseHttp2() throws IOException, InterruptedException, URISyntaxException, NoSuchAlgorithmException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .version(HttpClient.Version.HTTP_2)
+            .GET()
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.version(), equalTo(HttpClient.Version.HTTP_1_1));
+    }
+
+    @Test
+    public void shouldReturnStatusOKWhenSendGetRequestWithDummyHeaders() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .headers("key1", "value1", "key2", "value2")
+            .GET()
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldReturnStatusOKWhenSendGetRequestTimeoutSet() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .timeout(Duration.of(10, SECONDS))
+            .GET()
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldReturnNoContentWhenPostWithNoBody() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .POST(HttpRequest.BodyPublishers.noBody())
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+    }
+
+    @Test
+    public void shouldReturnSampleDataContentWhenPostWithBodyText() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .headers("Content-Type", "text/plain;charset=UTF-8")
+            .POST(HttpRequest.BodyPublishers.ofString("Sample request body"))
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.body(), containsString("Sample request body"));
+    }
+
+    @Test
+    public void shouldReturnSampleDataContentWhenPostWithInputStream() throws IOException, InterruptedException, URISyntaxException {
+        byte[] sampleData = "Sample request body".getBytes();
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .headers("Content-Type", "text/plain;charset=UTF-8")
+            .POST(HttpRequest.BodyPublishers.ofInputStream(() -> new ByteArrayInputStream(sampleData)))
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.body(), containsString("Sample request body"));
+    }
+
+    @Test
+    public void shouldReturnSampleDataContentWhenPostWithByteArrayProcessorStream() throws IOException, InterruptedException, URISyntaxException {
+        byte[] sampleData = "Sample request body".getBytes();
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .headers("Content-Type", "text/plain;charset=UTF-8")
+            .POST(HttpRequest.BodyPublishers.ofByteArray(sampleData))
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.body(), containsString("Sample request body"));
+    }
+
+    @Test
+    public void shouldReturnSampleDataContentWhenPostWithFileProcessorStream() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/post"))
+            .headers("Content-Type", "text/plain;charset=UTF-8")
+            .POST(HttpRequest.BodyPublishers.ofFile(Paths.get("src/test/resources/sample.txt")))
+            .build();
+
+        HttpResponse<String> response = HttpClient.newHttpClient()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertThat(response.body(), containsString("Sample file content"));
+    }
+
+}

core-java-11/src/test/java/com/baeldung/java11/httpclient/test/HttpResponseTest.java

@@ -0,0 +1,54 @@
+package com.baeldung.java11.httpclient.test;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertThat;
+
+import java.io.IOException;
+import java.net.HttpURLConnection;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+
+import org.junit.Test;
+
+public class HttpResponseTest {
+
+    @Test
+    public void shouldReturnStatusOKWhenSendGetRequest() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("https://postman-echo.com/get"))
+            .version(HttpClient.Version.HTTP_2)
+            .GET()
+            .build();
+
+        HttpResponse<String> response = HttpClient.newBuilder()
+            .followRedirects(HttpClient.Redirect.NORMAL)
+            .build()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.statusCode(), equalTo(HttpURLConnection.HTTP_OK));
+        assertNotNull(response.body());
+    }
+
+    @Test
+    public void shouldResponseURIDifferentThanRequestUIRWhenRedirect() throws IOException, InterruptedException, URISyntaxException {
+        HttpRequest request = HttpRequest.newBuilder()
+            .uri(new URI("http://stackoverflow.com"))
+            .version(HttpClient.Version.HTTP_2)
+            .GET()
+            .build();
+        HttpResponse<String> response = HttpClient.newBuilder()
+            .followRedirects(HttpClient.Redirect.NORMAL)
+            .build()
+            .send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(request.uri()
+            .toString(), equalTo("http://stackoverflow.com"));
+        assertThat(response.uri()
+            .toString(), equalTo("https://stackoverflow.com/"));
+    }
+
+}

core-java-8/README.md

@@ -4,9 +4,9 @@
 
 ### Relevant Articles: 
 - [Java 8 Collectors](http://www.baeldung.com/java-8-collectors)
-- [Guide to Java 8’s Functional Interfaces](http://www.baeldung.com/java-8-functional-interfaces)
+- [Functional Interfaces in Java 8](http://www.baeldung.com/java-8-functional-interfaces)
 - [Java 8 – Powerful Comparison with Lambdas](http://www.baeldung.com/java-8-sort-lambda)
-- [Java 8 New Features](http://www.baeldung.com/java-8-new-features)
+- [New Features in Java 8](http://www.baeldung.com/java-8-new-features)
 - [Lambda Expressions and Functional Interfaces: Tips and Best Practices](http://www.baeldung.com/java-8-lambda-expressions-tips)
 - [The Double Colon Operator in Java 8](http://www.baeldung.com/java-8-double-colon-operator)
 - [Guide to Java 8 groupingBy Collector](http://www.baeldung.com/java-groupingby-collector)
@@ -38,3 +38,5 @@
 - [Java @SafeVarargs Annotation](https://www.baeldung.com/java-safevarargs)
 - [Java @Deprecated Annotation](https://www.baeldung.com/java-deprecated)
 - [Java 8 Predicate Chain](https://www.baeldung.com/java-predicate-chain)
+- [Method References in Java](https://www.baeldung.com/java-method-references)
+- [Creating a Custom Annotation in Java](https://www.baeldung.com/java-custom-annotation)

core-java-8/pom.xml

@@ -4,8 +4,8 @@
     <groupId>com.baeldung</groupId>
     <artifactId>core-java-8</artifactId>
     <version>0.1.0-SNAPSHOT</version>
-    <packaging>jar</packaging>
     <name>core-java-8</name>
+    <packaging>jar</packaging>
 
     <parent>
         <groupId>com.baeldung</groupId>
@@ -180,7 +180,6 @@
         <commons-collections4.version>4.1</commons-collections4.version>
         <collections-generic.version>4.01</collections-generic.version>
         <commons-codec.version>1.10</commons-codec.version>
-        <lombok.version>1.16.12</lombok.version>
         <vavr.version>0.9.0</vavr.version>
         <protonpack.version>1.13</protonpack.version>
         <joda.version>2.10</joda.version>

core-java-8/src/main/java/com/baeldung/customannotations/Init.java

@@ -0,0 +1,13 @@
+package com.baeldung.customannotations;
+
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+@Retention(RUNTIME)
+@Target(METHOD)
+public @interface Init {
+
+}

core-java-8/src/main/java/com/baeldung/customannotations/JsonElement.java

@@ -0,0 +1,13 @@
+package com.baeldung.customannotations;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+@Retention(RUNTIME)
+@Target({ FIELD })
+public @interface JsonElement {
+    public String key() default "";
+}

core-java-8/src/main/java/com/baeldung/customannotations/JsonSerializable.java

@@ -0,0 +1,13 @@
+package com.baeldung.customannotations;
+
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+@Retention(RUNTIME)
+@Target(TYPE)
+public @interface JsonSerializable {
+
+}

core-java-8/src/main/java/com/baeldung/customannotations/JsonSerializationException.java

@@ -0,0 +1,10 @@
+package com.baeldung.customannotations;
+
+public class JsonSerializationException extends RuntimeException {
+
+    private static final long serialVersionUID = 1L;
+
+    public JsonSerializationException(String message) {
+        super(message);
+    }
+}

core-java-8/src/main/java/com/baeldung/customannotations/ObjectToJsonConverter.java

@@ -0,0 +1,67 @@
+package com.baeldung.customannotations;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
+public class ObjectToJsonConverter {
+    public String convertToJson(Object object) throws JsonSerializationException {
+        try {
+
+            checkIfSerializable(object);
+            initializeObject(object);
+            return getJsonString(object);
+
+        } catch (Exception e) {
+            throw new JsonSerializationException(e.getMessage());
+        }
+    }
+
+    private void checkIfSerializable(Object object) {
+        if (Objects.isNull(object)) {
+            throw new JsonSerializationException("Can't serialize a null object");
+        }
+
+        Class<?> clazz = object.getClass();
+        if (!clazz.isAnnotationPresent(JsonSerializable.class)) {
+            throw new JsonSerializationException("The class " + clazz.getSimpleName() + " is not annotated with JsonSerializable");
+        }
+    }
+
+    private void initializeObject(Object object) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {
+        Class<?> clazz = object.getClass();
+        for (Method method : clazz.getDeclaredMethods()) {
+            if (method.isAnnotationPresent(Init.class)) {
+                method.setAccessible(true);
+                method.invoke(object);
+            }
+        }
+    }
+
+    private String getJsonString(Object object) throws IllegalArgumentException, IllegalAccessException {
+        Class<?> clazz = object.getClass();
+        Map<String, String> jsonElementsMap = new HashMap<>();
+        for (Field field : clazz.getDeclaredFields()) {
+            field.setAccessible(true);
+            if (field.isAnnotationPresent(JsonElement.class)) {
+                jsonElementsMap.put(getKey(field), (String) field.get(object));
+            }
+        }
+
+        String jsonString = jsonElementsMap.entrySet()
+            .stream()
+            .map(entry -> "\"" + entry.getKey() + "\":\"" + entry.getValue() + "\"")
+            .collect(Collectors.joining(","));
+        return "{" + jsonString + "}";
+    }
+
+    private String getKey(Field field) {
+        String value = field.getAnnotation(JsonElement.class)
+            .key();
+        return value.isEmpty() ? field.getName() : value;
+    }
+}

core-java-8/src/main/java/com/baeldung/customannotations/Person.java

@@ -0,0 +1,66 @@
+package com.baeldung.customannotations;
+
+@JsonSerializable
+public class Person {
+    @JsonElement
+    private String firstName;
+    @JsonElement
+    private String lastName;
+    @JsonElement(key = "personAge")
+    private String age;
+
+    private String address;
+
+    public Person(String firstName, String lastName) {
+        super();
+        this.firstName = firstName;
+        this.lastName = lastName;
+    }
+
+    public Person(String firstName, String lastName, String age) {
+        this.firstName = firstName;
+        this.lastName = lastName;
+        this.age = age;
+    }
+
+    @Init
+    private void initNames() {
+        this.firstName = this.firstName.substring(0, 1)
+            .toUpperCase() + this.firstName.substring(1);
+        this.lastName = this.lastName.substring(0, 1)
+            .toUpperCase() + this.lastName.substring(1);
+    }
+
+    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 String getAge() {
+        return age;
+    }
+
+    public void setAge(String age) {
+        this.age = age;
+    }
+
+    public String getAddress() {
+        return address;
+    }
+
+    public void setAddress(String address) {
+        this.address = address;
+    }
+
+}

core-java-8/src/main/java/com/baeldung/streamreduce/application/Application.java

@@ -0,0 +1,62 @@
+package com.baeldung.streamreduce.application;
+
+import com.baeldung.streamreduce.entities.User;
+import com.baeldung.streamreduce.utilities.NumberUtils;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class Application {
+
+    public static void main(String[] args) {
+        List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6);
+        int result1 = numbers.stream().reduce(0, (a, b) -> a + b);
+        System.out.println(result1);
+        
+        int result2 = numbers.stream().reduce(0, Integer::sum);
+        System.out.println(result2);
+
+        List<String> letters = Arrays.asList("a", "b", "c", "d", "e");
+        String result3 = letters.stream().reduce("", (a, b) -> a + b);
+        System.out.println(result3);
+        
+        String result4 = letters.stream().reduce("", String::concat);
+        System.out.println(result4);
+
+        String result5 = letters.stream().reduce("", (a, b) -> a.toUpperCase() + b.toUpperCase());
+        System.out.println(result5);
+        
+        List<User> users = Arrays.asList(new User("John", 30), new User("Julie", 35));
+        int result6 = users.stream().reduce(0, (partialAgeResult, user) -> partialAgeResult + user.getAge(), Integer::sum);
+        System.out.println(result6);
+        
+        String result7 = letters.parallelStream().reduce("", String::concat);
+        System.out.println(result7);
+        
+        int result8 = users.parallelStream().reduce(0, (partialAgeResult, user) -> partialAgeResult + user.getAge(), Integer::sum);
+        System.out.println(result8);
+        
+        List<User> userList = new ArrayList<>();
+        for (int i = 0; i <= 1000000; i++) {
+            userList.add(new User("John" + i, i));
+        }
+        
+        long t1 = System.currentTimeMillis();
+        int result9 = userList.stream().reduce(0, (partialAgeResult, user) -> partialAgeResult + user.getAge(), Integer::sum);
+        long t2 = System.currentTimeMillis();
+        System.out.println(result9);
+        System.out.println("Sequential stream time: " + (t2 - t1) + "ms");
+        
+        long t3 = System.currentTimeMillis();
+        int result10 = userList.parallelStream().reduce(0, (partialAgeResult, user) -> partialAgeResult + user.getAge(), Integer::sum);
+        long t4 = System.currentTimeMillis();
+        System.out.println(result10);
+        System.out.println("Parallel stream time: " + (t4 - t3) + "ms");
+        
+        int result11 = NumberUtils.divideListElements(numbers, 1);
+        System.out.println(result11);
+        
+        int result12 = NumberUtils.divideListElementsWithExtractedTryCatchBlock(numbers, 0);
+        System.out.println(result12);
+    }    
+}

core-java-8/src/main/java/com/baeldung/streamreduce/entities/User.java

@@ -0,0 +1,25 @@
+package com.baeldung.streamreduce.entities;
+
+public class User {
+
+    private final String name;
+    private final int age;
+
+    public User(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+    
+    @Override
+    public String toString() {
+        return "User{" + "name=" + name + ", age=" + age + '}';
+    }
+}

core-java-8/src/main/java/com/baeldung/streamreduce/utilities/NumberUtils.java

@@ -0,0 +1,52 @@
+package com.baeldung.streamreduce.utilities;
+
+import java.util.List;
+import java.util.function.BiFunction;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public abstract class NumberUtils {
+
+    private static final Logger LOGGER = Logger.getLogger(NumberUtils.class.getName());
+
+    public static int divideListElements(List<Integer> values, Integer divider) {
+        return values.stream()
+                .reduce(0, (a, b) -> {
+                    try {
+                        return a / divider + b / divider;
+                    } catch (ArithmeticException e) {
+                        LOGGER.log(Level.INFO, "Arithmetic Exception: Division by Zero");
+                    }
+                    return 0;
+                });
+    }
+    
+    public static int divideListElementsWithExtractedTryCatchBlock(List<Integer> values, int divider) {
+        return values.stream().reduce(0, (a, b) -> divide(a, divider) + divide(b, divider));
+    }
+    
+    public static int divideListElementsWithApplyFunctionMethod(List<Integer> values, int divider) {
+        BiFunction<Integer, Integer, Integer> division = (a, b) -> a / b;
+        return values.stream().reduce(0, (a, b) -> applyFunction(division, a, divider) + applyFunction(division, b, divider));
+    }
+    
+    private static int divide(int value, int factor) {
+        int result = 0;
+        try {
+            result = value / factor;
+        } catch (ArithmeticException e) {
+            LOGGER.log(Level.INFO, "Arithmetic Exception: Division by Zero");
+        }
+        return result;
+    }
+    
+    private static int applyFunction(BiFunction<Integer, Integer, Integer> function, int a, int b) {
+        try {
+            return function.apply(a, b);
+        }
+        catch(Exception e) {
+            LOGGER.log(Level.INFO, "Exception occurred!");
+        }
+        return 0;
+    }
+}

core-java-8/src/test/java/com/baeldung/collectors/Java8CollectorsUnitTest.java

@@ -39,6 +39,7 @@ import static org.assertj.core.api.Assertions.assertThatThrownBy;
 public class Java8CollectorsUnitTest {
 
     private final List<String> givenList = Arrays.asList("a", "bb", "ccc", "dd");
+    private final List<String> listWithDuplicates = Arrays.asList("a", "bb", "c", "d", "bb");
 
     @Test
     public void whenCollectingToList_shouldCollectToList() throws Exception {
@@ -48,12 +49,19 @@ public class Java8CollectorsUnitTest {
     }
 
     @Test
-    public void whenCollectingToList_shouldCollectToSet() throws Exception {
+    public void whenCollectingToSet_shouldCollectToSet() throws Exception {
         final Set<String> result = givenList.stream().collect(toSet());
 
         assertThat(result).containsAll(givenList);
     }
 
+    @Test
+    public void givenContainsDuplicateElements_whenCollectingToSet_shouldAddDuplicateElementsOnlyOnce() throws Exception {
+        final Set<String> result = listWithDuplicates.stream().collect(toSet());
+
+        assertThat(result).hasSize(4);
+    }
+
     @Test
     public void whenCollectingToCollection_shouldCollectToCollection() throws Exception {
         final List<String> result = givenList.stream().collect(toCollection(LinkedList::new));
@@ -77,10 +85,23 @@ public class Java8CollectorsUnitTest {
     }
 
     @Test
-    public void whenCollectingToMap_shouldCollectToMapMerging() throws Exception {
+    public void whenCollectingToMapwWithDuplicates_shouldCollectToMapMergingTheIdenticalItems() throws Exception {
-        final Map<String, Integer> result = givenList.stream().collect(toMap(Function.identity(), String::length, (i1, i2) -> i1));
+        final Map<String, Integer> result = listWithDuplicates.stream().collect(
+          toMap(
+            Function.identity(),
+            String::length,
+            (item, identicalItem) -> item
+          )
+        );
 
-        assertThat(result).containsEntry("a", 1).containsEntry("bb", 2).containsEntry("ccc", 3).containsEntry("dd", 2);
+        assertThat(result).containsEntry("a", 1).containsEntry("bb", 2).containsEntry("c", 1).containsEntry("d", 1);
+    }
+
+    @Test
+    public void givenContainsDuplicateElements_whenCollectingToMap_shouldThrowException() throws Exception {
+        assertThatThrownBy(() -> {
+            listWithDuplicates.stream().collect(toMap(Function.identity(), String::length));
+        }).isInstanceOf(IllegalStateException.class);
     }
 
     @Test