Merge branch 'master' of https://github.com/eugenp/tutorials into story/BAEL-7636

apache-avro/src/main/java/com/baeldung/avro/util/serealization/AvroDeSerealizer.java

@@ -5,29 +5,37 @@ import org.apache.avro.io.DatumReader;
 import org.apache.avro.io.Decoder;
 import org.apache.avro.io.DecoderFactory;
 import org.apache.avro.specific.SpecificDatumReader;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 
 public class AvroDeSerealizer {
 
+    private static Logger logger = LoggerFactory.getLogger(AvroDeSerealizer.class);
+
     public AvroHttpRequest deSerealizeAvroHttpRequestJSON(byte[] data) {
         DatumReader<AvroHttpRequest> reader = new SpecificDatumReader<>(AvroHttpRequest.class);
         Decoder decoder = null;
         try {
-        decoder = DecoderFactory.get().jsonDecoder(AvroHttpRequest.getClassSchema(), new String(data));
+            decoder = DecoderFactory.get()
+                .jsonDecoder(AvroHttpRequest.getClassSchema(), new String(data));
             return reader.read(null, decoder);
         } catch (IOException e) {
-        return null;
+            logger.error("Deserialization error" + e.getMessage());
         }
+        return null;
     }
 
     public AvroHttpRequest deSerealizeAvroHttpRequestBinary(byte[] data) {
         DatumReader<AvroHttpRequest> employeeReader = new SpecificDatumReader<>(AvroHttpRequest.class);
-    Decoder decoder = DecoderFactory.get().binaryDecoder(data, null);
+        Decoder decoder = DecoderFactory.get()
+            .binaryDecoder(data, null);
         try {
             return employeeReader.read(null, decoder);
         } catch (IOException e) {
+            logger.error("Deserialization error" + e.getMessage());
+        }
         return null;
     }
 }
-}

apache-avro/src/main/java/com/baeldung/avro/util/serealization/AvroSerealizer.java

@@ -3,24 +3,29 @@ package com.baeldung.avro.util.serealization;
 import com.baeldung.avro.util.model.AvroHttpRequest;
 import org.apache.avro.io.*;
 import org.apache.avro.specific.SpecificDatumWriter;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 
 public class AvroSerealizer {
 
+    private static final Logger logger = LoggerFactory.getLogger(AvroSerealizer.class);
+
     public byte[] serealizeAvroHttpRequestJSON(AvroHttpRequest request) {
         DatumWriter<AvroHttpRequest> writer = new SpecificDatumWriter<>(AvroHttpRequest.class);
         byte[] data = new byte[0];
         ByteArrayOutputStream stream = new ByteArrayOutputStream();
         Encoder jsonEncoder = null;
         try {
-        jsonEncoder = EncoderFactory.get().jsonEncoder(AvroHttpRequest.getClassSchema(), stream);
+            jsonEncoder = EncoderFactory.get()
+                .jsonEncoder(AvroHttpRequest.getClassSchema(), stream);
             writer.write(request, jsonEncoder);
             jsonEncoder.flush();
             data = stream.toByteArray();
         } catch (IOException e) {
-        data =null;
+            logger.error("Serialization error " + e.getMessage());
         }
         return data;
     }
@@ -29,13 +34,14 @@ public byte[] serealizeAvroHttpRequestBinary(AvroHttpRequest request){
         DatumWriter<AvroHttpRequest> writer = new SpecificDatumWriter<>(AvroHttpRequest.class);
         byte[] data = new byte[0];
         ByteArrayOutputStream stream = new ByteArrayOutputStream();
-    Encoder jsonEncoder = EncoderFactory.get().binaryEncoder(stream,null);
+        Encoder jsonEncoder = EncoderFactory.get()
+            .binaryEncoder(stream, null);
         try {
             writer.write(request, jsonEncoder);
             jsonEncoder.flush();
             data = stream.toByteArray();
         } catch (IOException e) {
-        data = null;
+            logger.error("Serialization error " + e.getMessage());
         }
 
         return data;

apache-avro/src/test/java/com/baeldung/avro/util/serealization/AvroSerealizerDeSerealizerTest.java

@@ -24,8 +24,10 @@ public class AvroSerealizerDeSerealizerTest {
         serealizer = new AvroSerealizer();
         deSerealizer = new AvroDeSerealizer();
 
-        ClientIdentifier clientIdentifier = ClientIdentifier.newBuilder().
-                setHostName("localhost").setIpAddress("255.255.255.0").build();
+        ClientIdentifier clientIdentifier = ClientIdentifier.newBuilder()
+            .setHostName("localhost")
+            .setIpAddress("255.255.255.0")
+            .build();
 
         List<CharSequence> employees = new ArrayList();
         employees.add("James");
@@ -33,9 +35,12 @@ public class AvroSerealizerDeSerealizerTest {
         employees.add("David");
         employees.add("Han");
 
-        request = AvroHttpRequest.newBuilder().setRequestTime(01l)
-                .setActive(Active.YES).setClientIdentifier(clientIdentifier)
-                .setEmployeeNames(employees).build();
+        request = AvroHttpRequest.newBuilder()
+            .setRequestTime(01l)
+            .setActive(Active.YES)
+            .setClientIdentifier(clientIdentifier)
+            .setEmployeeNames(employees)
+            .build();
     }
 
     @After
@@ -43,33 +48,36 @@ public class AvroSerealizerDeSerealizerTest {
     }
 
     @Test
-public void WhenSerialized_UsingJSONEncoder_ObjectGetsSerialized(){
+    public void WhenSerializedUsingJSONEncoder_thenObjectGetsSerialized() {
         byte[] data = serealizer.serealizeAvroHttpRequestJSON(request);
         assertTrue(Objects.nonNull(data));
         assertTrue(data.length > 0);
     }
 
     @Test
-public void WhenSerialized_UsingBinaryEncoder_ObjectGetsSerialized(){
+    public void WhenSerializedUsingBinaryEncoder_thenObjectGetsSerialized() {
         byte[] data = serealizer.serealizeAvroHttpRequestBinary(request);
         assertTrue(Objects.nonNull(data));
         assertTrue(data.length > 0);
     }
 
     @Test
-public void WhenDeserialize_UsingJSONDecoder_ActualAndExpectedObjectsAreEqual(){
+    public void WhenDeserializeUsingJSONDecoder_thenActualAndExpectedObjectsAreEqual() {
         byte[] data = serealizer.serealizeAvroHttpRequestJSON(request);
         AvroHttpRequest actualRequest = deSerealizer.deSerealizeAvroHttpRequestJSON(data);
         assertEquals(actualRequest, request);
-    assertTrue(actualRequest.getRequestTime().equals(request.getRequestTime()));
+        assertTrue(actualRequest.getRequestTime()
+            .equals(request.getRequestTime()));
     }
 
     @Test
-public void WhenDeserialize_UsingBinaryecoder_ActualAndExpectedObjectsAreEqual(){
+    public void WhenDeserializeUsingBinaryecoder_thenActualAndExpectedObjectsAreEqual() {
         byte[] data = serealizer.serealizeAvroHttpRequestBinary(request);
         AvroHttpRequest actualRequest = deSerealizer.deSerealizeAvroHttpRequestBinary(data);
         assertEquals(actualRequest, request);
-    assertTrue(actualRequest.getRequestTime().equals(request.getRequestTime()));
-}
+        assertTrue(actualRequest.getRequestTime()
+            .equals(request.getRequestTime()));
+    }
+    
 }
 

aws/pom.xml

@@ -137,7 +137,7 @@
         <aws-lambda-java-core.version>1.1.0</aws-lambda-java-core.version>
         <gson.version>2.8.0</gson.version>
         <aws-java-sdk.version>1.11.290</aws-java-sdk.version>
-        <mockito-core.version>2.8.9</mockito-core.version>
+        <mockito-core.version>2.21.0</mockito-core.version>
         <assertj-core.version>3.8.0</assertj-core.version>
         <dynamodblocal.version>1.11.86</dynamodblocal.version>
         <dynamodblocal.repository.url>https://s3-us-west-2.amazonaws.com/dynamodb-local/release</dynamodblocal.repository.url>

core-java-8/README.md

@@ -14,7 +14,6 @@
 - [Guide to Java 8 groupingBy Collector](http://www.baeldung.com/java-groupingby-collector)
 - [Strategy Design Pattern in Java 8](http://www.baeldung.com/java-strategy-pattern)
 - [Java 8 and Infinite Streams](http://www.baeldung.com/java-inifinite-streams)
-- [String Operations with Java Streams](http://www.baeldung.com/java-stream-operations-on-strings)
 - [Exceptions in Java 8 Lambda Expressions](http://www.baeldung.com/java-lambda-exceptions)
 - [Java 8 Stream findFirst() vs. findAny()](http://www.baeldung.com/java-stream-findfirst-vs-findany)
 - [Guide to Java 8 Comparator.comparing()](http://www.baeldung.com/java-8-comparator-comparing)
@@ -34,13 +33,11 @@
 - [Copy a File with Java](http://www.baeldung.com/java-copy-file)
 - [Static and Default Methods in Interfaces in Java](http://www.baeldung.com/java-static-default-methods)
 - [Iterable to Stream in Java](http://www.baeldung.com/java-iterable-to-stream)
-- [Converting String to Stream of chars](http://www.baeldung.com/java-string-to-stream)
 - [How to Iterate Over a Stream With Indices](http://www.baeldung.com/java-stream-indices)
 - [Efficient Word Frequency Calculator in Java](http://www.baeldung.com/java-word-frequency)
 - [Primitive Type Streams in Java 8](http://www.baeldung.com/java-8-primitive-streams)
 - [Fail-Safe Iterator vs Fail-Fast Iterator](http://www.baeldung.com/java-fail-safe-vs-fail-fast-iterator)
 - [Shuffling Collections In Java](http://www.baeldung.com/java-shuffle-collection)
-- [Java 8 StringJoiner](http://www.baeldung.com/java-string-joiner)
 - [Introduction to Spliterator in Java](http://www.baeldung.com/java-spliterator)
 - [Java 8 Math New Methods](http://www.baeldung.com/java-8-math)
 - [Overview of Java Built-in Annotations](http://www.baeldung.com/java-default-annotations)
@@ -54,7 +51,6 @@
 - [Java 8 Unsigned Arithmetic Support](http://www.baeldung.com/java-unsigned-arithmetic)
 - [How to Get the Start and the End of a Day using Java](http://www.baeldung.com/java-day-start-end)
 - [Generalized Target-Type Inference in Java](http://www.baeldung.com/java-generalized-target-type-inference)
-- [Image to Base64 String Conversion](http://www.baeldung.com/java-base64-image-string)
 - [Calculate Age in Java](http://www.baeldung.com/java-get-age)
 - [Copy a List to Another List in Java](http://www.baeldung.com/java-copy-list-to-another)
 - [Increment Date in Java](http://www.baeldung.com/java-increment-date)

core-java-9/README.md

@@ -17,7 +17,6 @@
 - [Java 9 Reactive Streams](http://www.baeldung.com/java-9-reactive-streams)
 - [How to Get All Dates Between Two Dates?](http://www.baeldung.com/java-between-dates)
 - [Java 9 java.util.Objects Additions](http://www.baeldung.com/java-9-objects-new)
-- [Compact Strings in Java 9](http://www.baeldung.com/java-9-compact-string)
 - [Convert Date to LocalDate or LocalDateTime and Back](http://www.baeldung.com/java-date-to-localdate-and-localdatetime)
 - [Java 9 Variable Handles Demistyfied](http://www.baeldung.com/java-variable-handles)
 - [Exploring the New HTTP Client in Java 9](http://www.baeldung.com/java-9-http-client)

core-java-collections/src/test/java/com/baeldung/list/removefirst/RemoveFirstElementUnitTest.java

@@ -4,6 +4,7 @@ import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.*;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.LinkedList;
 import java.util.List;
 
@@ -48,4 +49,14 @@ public class RemoveFirstElementUnitTest {
         assertThat(linkedList, not(contains("cat")));
     }
 
+    @Test
+    public void givenStringArray_whenRemovingFirstElement_thenArrayIsSmallerAndElementRemoved() {
+        String[] stringArray = {"foo", "bar", "baz"};
+
+        String[] modifiedArray = Arrays.copyOfRange(stringArray, 1, stringArray.length);
+
+        assertThat(modifiedArray.length, is(2));
+        assertThat(modifiedArray[0], is("bar"));
+    }
+
 }

core-java-collections/src/test/java/org/baeldung/java/collections/CollectionsEmpty.java

@@ -0,0 +1,26 @@
+package org.baeldung.java.collections;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import org.junit.Assert;
+import org.junit.Test;
+
+class CollectionsEmpty {
+
+    @Test
+    public void givenArrayList_whenAddingElement_addsNewElement() {
+        ArrayList<String> mutableList = new ArrayList<>();
+        mutableList.add("test");
+
+        Assert.assertEquals(mutableList.size(), 1);
+        Assert.assertEquals(mutableList.get(0), "test");
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void givenCollectionsEmptyList_whenAddingElement_throwsUnsupportedOperationException() {
+        List<String> immutableList = Collections.emptyList();
+        immutableList.add("test");
+    }
+
+}

core-java-concurrency-collections/.gitignore

@@ -0,0 +1,26 @@
+*.class
+
+0.*
+
+#folders#
+/target
+/neoDb*
+/data
+/src/main/webapp/WEB-INF/classes
+*/META-INF/*
+.resourceCache
+
+# Packaged files #
+*.jar
+*.war
+*.ear
+
+# Files generated by integration tests
+*.txt
+backup-pom.xml
+/bin/
+/temp
+
+#IntelliJ specific
+.idea/
+*.iml

core-java-concurrency-collections/README.md

@@ -0,0 +1,15 @@
+=========
+
+## Core Java Concurrency Collections Examples
+
+### Relevant Articles: 
+- [Guide to java.util.concurrent.BlockingQueue](http://www.baeldung.com/java-blocking-queue)
+- [A Guide to ConcurrentMap](http://www.baeldung.com/java-concurrent-map)
+- [Guide to PriorityBlockingQueue in Java](http://www.baeldung.com/java-priority-blocking-queue)
+- [Avoiding the ConcurrentModificationException in Java](http://www.baeldung.com/java-concurrentmodificationexception)
+- [Custom Thread Pools In Java 8 Parallel Streams](http://www.baeldung.com/java-8-parallel-streams-custom-threadpool)
+- [Guide to DelayQueue](http://www.baeldung.com/java-delay-queue)
+- [A Guide to Java SynchronousQueue](http://www.baeldung.com/java-synchronous-queue)
+- [Guide to the Java TransferQueue](http://www.baeldung.com/java-transfer-queue)
+- [Guide to the ConcurrentSkipListMap](http://www.baeldung.com/java-concurrent-skip-list-map)
+- [Guide to CopyOnWriteArrayList](http://www.baeldung.com/java-copy-on-write-arraylist)

core-java-concurrency-collections/pom.xml

@@ -0,0 +1,94 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung</groupId>
+    <artifactId>core-java-concurrency-collections</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    <name>core-java-concurrency-collections</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>${commons-collections4.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>${commons-io.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-math3</artifactId>
+            <version>${commons-math3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.jayway.awaitility</groupId>
+            <artifactId>awaitility</artifactId>
+            <version>${avaitility.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-concurrency-collections</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-dependency-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <id>copy-dependencies</id>
+                        <phase>prepare-package</phase>
+                        <goals>
+                            <goal>copy-dependencies</goal>
+                        </goals>
+                        <configuration>
+                            <outputDirectory>${project.build.directory}/libs</outputDirectory>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+            
+        </plugins>
+    </build>
+
+    <properties>
+        <!-- util -->
+        <guava.version>21.0</guava.version>
+        <commons-lang3.version>3.5</commons-lang3.version>
+        <commons-math3.version>3.6.1</commons-math3.version>
+        <commons-collections4.version>4.1</commons-collections4.version>
+        <collections-generic.version>4.01</collections-generic.version>
+        <!-- testing -->
+        <assertj.version>3.6.1</assertj.version>
+        <avaitility.version>1.7.0</avaitility.version>
+    </properties>
+
+</project>

core-java-concurrency-collections/src/main/java/com/baeldung/concurrent/blockingqueue/BlockingQueueUsage.java

@@ -10,15 +10,18 @@ public class BlockingQueueUsage {
         int N_CONSUMERS = Runtime.getRuntime().availableProcessors();
         int poisonPill = Integer.MAX_VALUE;
         int poisonPillPerProducer = N_CONSUMERS / N_PRODUCERS;
-
+        int mod = N_CONSUMERS % N_PRODUCERS;
         BlockingQueue<Integer> queue = new LinkedBlockingQueue<>(BOUND);
 
-        for (int i = 0; i < N_PRODUCERS; i++) {
+        for (int i = 1; i < N_PRODUCERS; i++) {
             new Thread(new NumbersProducer(queue, poisonPill, poisonPillPerProducer)).start();
         }
 
         for (int j = 0; j < N_CONSUMERS; j++) {
             new Thread(new NumbersConsumer(queue, poisonPill)).start();
         }
+        
+        new Thread(new NumbersProducer(queue, poisonPill, poisonPillPerProducer+mod)).start();
+
     }
 }

core-java-concurrency-collections/src/main/resources/logback.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>web - %date [%thread] %-5level %logger{36} - %message%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <logger name="org.springframework" level="WARN" />
+    <logger name="org.springframework.transaction" level="WARN" />
+
+    <!-- in order to debug some marshalling issues, this needs to be TRACE -->
+    <logger name="org.springframework.web.servlet.mvc" level="WARN" />
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

core-java-concurrency-collections/src/test/resources/.gitignore

@@ -0,0 +1,13 @@
+*.class
+
+#folders#
+/target
+/neoDb*
+/data
+/src/main/webapp/WEB-INF/classes
+*/META-INF/*
+
+# Packaged files #
+*.jar
+*.war
+*.ear

core-java-concurrency/README.md

@@ -7,22 +7,12 @@
 - [A Guide to the Java ExecutorService](http://www.baeldung.com/java-executor-service-tutorial)
 - [Introduction to Thread Pools in Java](http://www.baeldung.com/thread-pool-java-and-guava)
 - [Guide to java.util.concurrent.Future](http://www.baeldung.com/java-future)
-- [Guide to java.util.concurrent.BlockingQueue](http://www.baeldung.com/java-blocking-queue)
 - [Guide to CountDownLatch in Java](http://www.baeldung.com/java-countdown-latch)
-- [A Guide to ConcurrentMap](http://www.baeldung.com/java-concurrent-map)
-- [Guide to PriorityBlockingQueue in Java](http://www.baeldung.com/java-priority-blocking-queue)
-- [Avoiding the ConcurrentModificationException in Java](http://www.baeldung.com/java-concurrentmodificationexception)
-- [Custom Thread Pools In Java 8 Parallel Streams](http://www.baeldung.com/java-8-parallel-streams-custom-threadpool)
 - [Guide to java.util.concurrent.Locks](http://www.baeldung.com/java-concurrent-locks)
 - [An Introduction to ThreadLocal in Java](http://www.baeldung.com/java-threadlocal)
-- [Guide to DelayQueue](http://www.baeldung.com/java-delay-queue)
-- [A Guide to Java SynchronousQueue](http://www.baeldung.com/java-synchronous-queue)
-- [Guide to the Java TransferQueue](http://www.baeldung.com/java-transfer-queue)
-- [Guide to the ConcurrentSkipListMap](http://www.baeldung.com/java-concurrent-skip-list-map)
 - [Difference Between Wait and Sleep in Java](http://www.baeldung.com/java-wait-and-sleep)
 - [LongAdder and LongAccumulator in Java](http://www.baeldung.com/java-longadder-and-longaccumulator)
 - [The Dining Philosophers Problem in Java](http://www.baeldung.com/java-dining-philoshophers)
-- [Guide to CopyOnWriteArrayList](http://www.baeldung.com/java-copy-on-write-arraylist)
 - [Guide to the Java Phaser](http://www.baeldung.com/java-phaser)
 - [Guide to Synchronized Keyword in Java](http://www.baeldung.com/java-synchronized)
 - [An Introduction to Atomic Variables in Java](http://www.baeldung.com/java-atomic-variables)

core-java-persistence/README.md

@@ -0,0 +1,8 @@
+=========
+
+## Core Java Persistence Examples
+
+### Relevant Articles: 
+- [Introduction to JDBC](http://www.baeldung.com/java-jdbc)
+- [Batch Processing in JDBC](http://www.baeldung.com/jdbc-batch-processing)
+- [Introduction to the JDBC RowSet Interface in Java](http://www.baeldung.com/java-jdbc-rowset)

core-java/README.md

@@ -3,18 +3,14 @@
 ## Core Java Cookbooks and Examples
 
 ### Relevant Articles: 
-- [Java – Generate Random String](http://www.baeldung.com/java-random-string)
 - [Java Timer](http://www.baeldung.com/java-timer-and-timertask)
 - [How to Run a Shell Command in Java](http://www.baeldung.com/run-shell-command-in-java)
 - [MD5 Hashing in Java](http://www.baeldung.com/java-md5)
 - [Guide to Java Reflection](http://www.baeldung.com/java-reflection)
 - [A Guide to Java Sockets](http://www.baeldung.com/a-guide-to-java-sockets)
-- [Convert char to String in Java](http://www.baeldung.com/java-convert-char-to-string)
-- [Convert String to int or Integer in Java](http://www.baeldung.com/java-convert-string-to-int-or-integer)
 - [Java – Try with Resources](http://www.baeldung.com/java-try-with-resources)
 - [Guide to the Fork/Join Framework in Java](http://www.baeldung.com/java-fork-join)
 - [How to Print Screen in Java](http://www.baeldung.com/print-screen-in-java)
-- [How to Convert String to different data types in Java](http://www.baeldung.com/java-string-conversions)
 - [Introduction to Java Generics](http://www.baeldung.com/java-generics)
 - [Generate equals() and hashCode() with Eclipse](http://www.baeldung.com/java-eclipse-equals-and-hashcode)
 - [A Guide To Java Regular Expressions API](http://www.baeldung.com/regular-expressions-java)
@@ -37,8 +33,6 @@
 - [A Quick JUnit vs TestNG Comparison](http://www.baeldung.com/junit-vs-testng)
 - [Java Primitive Conversions](http://www.baeldung.com/java-primitive-conversions)
 - [Java Money and the Currency API](http://www.baeldung.com/java-money-and-currency)
-- [Converting Strings to Enums in Java](http://www.baeldung.com/java-string-to-enum)
-- [Quick Guide to the Java StringTokenizer](http://www.baeldung.com/java-stringtokenizer)
 - [JVM Log Forging](http://www.baeldung.com/jvm-log-forging)
 - [Guide to sun.misc.Unsafe](http://www.baeldung.com/java-unsafe)
 - [How to Perform a Simple HTTP Request in Java](http://www.baeldung.com/java-http-request)
@@ -53,36 +47,28 @@
 - [How to Get a Name of a Method Being Executed?](http://www.baeldung.com/java-name-of-executing-method)
 - [Dynamic Proxies in Java](http://www.baeldung.com/java-dynamic-proxies)
 - [How to Copy an Array in Java](http://www.baeldung.com/java-array-copy)
-- [Introduction to JDBC](http://www.baeldung.com/java-jdbc)
 - [Period and Duration in Java](http://www.baeldung.com/java-period-duration)
 - [Converting a Stack Trace to a String in Java](http://www.baeldung.com/java-stacktrace-to-string)
-- [Count Occurrences of a Char in a String](http://www.baeldung.com/java-count-chars)
 - [Java Double Brace Initialization](http://www.baeldung.com/java-double-brace-initialization)
 - [The StackOverflowError in Java](http://www.baeldung.com/java-stack-overflow-error)
-- [Split a String in Java](http://www.baeldung.com/java-split-string)
 - [Introduction to Java Serialization](http://www.baeldung.com/java-serialization)
-- [How to Remove the Last Character of a String?](http://www.baeldung.com/java-remove-last-character-of-string)
 - [ClassNotFoundException vs NoClassDefFoundError](http://www.baeldung.com/java-classnotfoundexception-and-noclassdeffounderror)
 - [Guide to UUID in Java](http://www.baeldung.com/java-uuid)
 - [Guide to Escaping Characters in Java RegExps](http://www.baeldung.com/java-regexp-escape-char)
 - [Guide to hashCode() in Java](http://www.baeldung.com/java-hashcode)
 - [Difference between URL and URI](http://www.baeldung.com/java-url-vs-uri)
 - [Broadcasting and Multicasting in Java](http://www.baeldung.com/java-broadcast-multicast)
-- [CharSequence vs. String in Java](http://www.baeldung.com/java-char-sequence-string)
 - [Period and Duration in Java](http://www.baeldung.com/java-period-duration)
 - [Guide to the Diamond Operator in Java](http://www.baeldung.com/java-diamond-operator)
 - [“Sneaky Throws” in Java](http://www.baeldung.com/java-sneaky-throws)
 - [OutOfMemoryError: GC Overhead Limit Exceeded](http://www.baeldung.com/java-gc-overhead-limit-exceeded)
-- [StringBuilder and StringBuffer in Java](http://www.baeldung.com/java-string-builder-string-buffer)
 - [Creating a Java Compiler Plugin](http://www.baeldung.com/java-build-compiler-plugin)
 - [A Guide to the Static Keyword in Java](http://www.baeldung.com/java-static)
 - [Initializing Arrays in Java](http://www.baeldung.com/java-initialize-array)
-- [Guide to Java String Pool](http://www.baeldung.com/java-string-pool)
 - [Quick Example - Comparator vs Comparable in Java](http://www.baeldung.com/java-comparator-comparable)
 - [Quick Guide to Java Stack](http://www.baeldung.com/java-stack)
 - [The Java continue and break Keywords](http://www.baeldung.com/java-continue-and-break)
 - [Guide to java.util.Formatter](http://www.baeldung.com/java-string-formatter)
-- [Batch Processing in JDBC](http://www.baeldung.com/jdbc-batch-processing)
 - [Check if a Java Array Contains a Value](http://www.baeldung.com/java-array-contains-value)
 - [How to Invert an Array in Java](http://www.baeldung.com/java-invert-array)
 - [Guide to the Cipher Class](http://www.baeldung.com/java-cipher-class)
@@ -90,7 +76,6 @@
 - [Implementing a Binary Tree in Java](http://www.baeldung.com/java-binary-tree)
 - [A Guide to ThreadLocalRandom in Java](http://www.baeldung.com/java-thread-local-random)
 - [RegEx for matching Date Pattern in Java](http://www.baeldung.com/java-date-regular-expressions)
-- [Introduction to the JDBC RowSet Interface in Java](http://www.baeldung.com/java-jdbc-rowset)
 - [Nested Classes in Java](http://www.baeldung.com/java-nested-classes)
 - [A Guide to Java Loops](http://www.baeldung.com/java-loops)
 - [Varargs in Java](http://www.baeldung.com/java-varargs)
@@ -105,15 +90,12 @@
 - [The Trie Data Structure in Java](http://www.baeldung.com/trie-java)
 - [Introduction to Javadoc](http://www.baeldung.com/javadoc)
 - [How to Make a Deep Copy of an Object in Java](http://www.baeldung.com/java-deep-copy)
-- [Check if a String is a Palindrome](http://www.baeldung.com/java-palindrome)
-- [Comparing Strings in Java](http://www.baeldung.com/java-compare-strings)
 - [Guide to Inheritance in Java](http://www.baeldung.com/java-inheritance)
 - [Guide to Externalizable Interface in Java](http://www.baeldung.com/java-externalizable)
 - [Object Type Casting in Java](http://www.baeldung.com/java-type-casting)
 - [A Practical Guide to DecimalFormat](http://www.baeldung.com/java-decimalformat)
 - [How to Detect the OS Using Java](http://www.baeldung.com/java-detect-os)
 - [ASCII Art in Java](http://www.baeldung.com/ascii-art-in-java)
-- [An Advanced Tagging Implementation with JPA](http://www.baeldung.com/jpa-tagging-advanced)
 - [Handling Daylight Savings Time in Java](http://www.baeldung.com/java-daylight-savings)
 - [Inheritance and Composition (Is-a vs Has-a relationship) in Java](http://www.baeldung.com/java-inheritance-composition)
 - [Finding Max/Min of a List or Collection](http://www.baeldung.com/java-collection-min-max)
@@ -139,11 +121,9 @@
 - [Infinite Loops in Java](http://www.baeldung.com/infinite-loops-java)
 - [Using Java Assertions](http://www.baeldung.com/java-assert)
 - [Pass-By-Value as a Parameter Passing Mechanism in Java](http://www.baeldung.com/java-pass-by-value-or-pass-by-reference)
-- [Check If a String Is Numeric in Java](http://www.baeldung.com/java-check-string-number)
 - [Variable and Method Hiding in Java](http://www.baeldung.com/java-variable-method-hiding)
 - [Access Modifiers in Java](http://www.baeldung.com/java-access-modifiers)
 - [Infinite Loops in Java](http://www.baeldung.com/infinite-loops-java)
-- [Why Use char[] Array Over a String for Storing Passwords in Java?](http://www.baeldung.com/java-storing-passwords)
 - [Introduction to Creational Design Patterns](http://www.baeldung.com/creational-design-patterns)
 - [Proxy, Decorator, Adapter and Bridge Patterns](http://www.baeldung.com/java-structural-design-patterns)
 - [Singletons in Java](http://www.baeldung.com/java-singleton)
@@ -157,7 +137,6 @@
 - [Importance of Main Manifest Attribute in a Self-Executing JAR](http://www.baeldung.com/java-jar-executable-manifest-main-class)
 - [Extracting Year, Month and Day from Date in Java](http://www.baeldung.com/java-year-month-day)
 - [Get Date Without Time in Java](http://www.baeldung.com/java-date-without-time)
-- [Convert a String to Title Case](http://www.baeldung.com/java-string-title-case)
 - [How to Get the File Extension of a File in Java](http://www.baeldung.com/java-file-extension)
 - [Immutable Objects in Java](http://www.baeldung.com/java-immutable-object)
 - [Console I/O in Java](http://www.baeldung.com/java-console-input-output)
@@ -171,3 +150,4 @@
 - [Guide to Java Instrumentation](http://www.baeldung.com/java-instrumentation)
 - [Getting a File’s Mime Type in Java](http://www.baeldung.com/java-file-mime-type)
 - [Common Java Exceptions](http://www.baeldung.com/java-common-exceptions)
+- [Java Constructors vs Static Factory Methods](https://www.baeldung.com/java-constructors-vs-static-factory-methods)

core-java/pom.xml

@@ -137,11 +137,6 @@
             <artifactId>mail</artifactId>
             <version>${javax.mail.version}</version>
         </dependency>
-        <dependency>
-            <groupId>com.ibm.icu</groupId>
-            <artifactId>icu4j</artifactId>
-            <version>${icu4j.version}</version>
-        </dependency>
         <!-- Mime Type Resolution Libraries -->
         <dependency>
             <groupId>org.apache.tika</groupId>

core-java/src/main/java/com/baeldung/constructorsstaticfactorymethods/application/Application.java

@@ -0,0 +1,12 @@
+package com.baeldung.constructorsstaticfactorymethods.application;
+
+import com.baeldung.constructorsstaticfactorymethods.entities.User;
+ 
+public class Application {
+
+    public static void main(String[] args) {
+        User user1 = User.createWithDefaultCountry("John", "john@domain.com");
+        User user2 = User.createWithLoggedInstantiationTime("John", "john@domain.com", "Argentina");
+        User user3 = User.getSingletonInstance("John", "john@domain.com", "Argentina");
+    }
+}

core-java/src/main/java/com/baeldung/constructorsstaticfactorymethods/entities/User.java

@@ -0,0 +1,63 @@
+package com.baeldung.constructorsstaticfactorymethods.entities;
+
+import java.time.LocalTime;
+import java.util.logging.ConsoleHandler;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import java.util.logging.SimpleFormatter;
+
+public class User {
+
+    private static volatile User instance = null;
+    private static final Logger LOGGER = Logger.getLogger(User.class.getName());
+    private final String name;
+    private final String email;
+    private final String country;
+    
+    public static User createWithDefaultCountry(String name, String email) {
+        return new User(name, email, "Argentina");
+    }
+
+    public static User createWithLoggedInstantiationTime(String name, String email, String country) {
+        setLoggerProperties();
+        LOGGER.log(Level.INFO, "Creating User instance at : {0}", LocalTime.now());
+        return new User(name, email, country);
+    }
+
+    public static User getSingletonInstance(String name, String email, String country) {
+        if (instance == null) {
+            synchronized (User.class) {
+                if (instance == null) {
+                    instance = new User(name, email, country);
+                }
+            }
+        }
+        return instance;
+
+    }
+
+    private User(String name, String email, String country) {
+        this.name = name;
+        this.email = email;
+        this.country = country;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public String getCountry() {
+        return country;
+    }
+    
+    private static void setLoggerProperties() {
+        ConsoleHandler handler = new ConsoleHandler();
+        handler.setLevel(Level.INFO);
+        handler.setFormatter(new SimpleFormatter());
+        LOGGER.addHandler(handler);
+    }
+}

core-java/src/main/java/com/baeldung/exceptionhandling/Exceptions.java

@@ -25,7 +25,11 @@ public class Exceptions {
     }
 
     public List<Player> loadAllPlayers(String playersFile) throws IOException{
+        try {
             throw new IOException();
+        } catch(IOException ex) {
+            throw new IllegalStateException();
+        }
     }
 
     public int getPlayerScoreThrows(String playerFile) throws FileNotFoundException {		 
@@ -160,7 +164,13 @@ public class Exceptions {
     }
 
     public void throwAsGotoAntiPattern() throws MyException {
+        try {
+            // bunch of code
             throw new MyException();
+            // second bunch of code
+        } catch ( MyException e ) {
+            // third bunch of code
+        }
     }
 
     public int getPlayerScoreSwallowingExceptionAntiPattern(String playerFile) {

core-java/src/main/java/com/baeldung/hashcode/entities/User.java

@@ -25,7 +25,7 @@ public class User {
         if (this.getClass() != o.getClass())
             return false;
         User user = (User) o;
-        return id != user.id && (!name.equals(user.name) && !email.equals(user.email));
+        return id == user.id && (name.equals(user.name) && email.equals(user.email));
     }
 
     @Override
@@ -38,4 +38,5 @@ public class User {
         return hash;
     }
     // getters and setters here
+    
 }

core-java/src/test/java/com/baeldung/array/RemoveFirstElementUnitTest.java

@@ -1,42 +0,0 @@
-package com.baeldung.array;
-
-import org.junit.Test;
-
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.LinkedList;
-import java.util.List;
-
-import static org.assertj.core.api.Assertions.assertThat;
-
-public class RemoveFirstElementUnitTest {
-
-    @Test
-    public void givenStringArray_whenRemovingFirstElement_thenArrayIsSmallerAndElementRemoved() {
-        String[] stringArray = {"foo", "bar", "baz"};
-
-        String[] modifiedArray = Arrays.copyOfRange(stringArray, 1, stringArray.length);
-
-        assertThat(modifiedArray.length).isEqualTo(2);
-        assertThat(modifiedArray[0]).isEqualTo("bar");
-    }
-
-    @Test
-    public void givenArrayList_whenRemovingFirstElement_thenListSmallerAndElementRemoved() {
-        List<String> stringList = new ArrayList<>(Arrays.asList("foo", "bar", "baz"));
-        stringList.remove(0);
-
-        assertThat(stringList.size()).isEqualTo(2);
-        assertThat(stringList.get(0)).isEqualTo("bar");
-    }
-
-    @Test
-    public void givenLinkedList_whenRemovingFirstElement_thenListSmallerAndElementRemoved() {
-        List<String> stringList = new LinkedList<>(Arrays.asList("foo", "bar", "baz"));
-        stringList.remove(0);
-
-        assertThat(stringList.size()).isEqualTo(2);
-        assertThat(stringList.get(0)).isEqualTo("bar");
-    }
-
-}

core-java/src/test/java/com/baeldung/constructorsstaticfactorymethods/UserUnitTest.java

@@ -0,0 +1,43 @@
+package com.baeldung.constructorsstaticfactorymethods;
+
+import com.baeldung.constructorsstaticfactorymethods.entities.User;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class UserUnitTest {
+    
+    @Test
+    public void givenUserClass_whenCalledcreateWithDefaultCountry_thenCorrect() {
+        assertThat(User.createWithDefaultCountry("John", "john@domain.com")).isInstanceOf(User.class);
+    }
+    
+    @Test
+    public void givenUserIntanceCreatedWithcreateWithDefaultCountry_whenCalledgetName_thenCorrect() {
+        User user = User.createWithDefaultCountry("John", "john@domain.com");
+        assertThat(user.getName()).isEqualTo("John");
+    }
+    
+    @Test
+    public void givenUserIntanceCreatedWithcreateWithDefaultCountry_whenCalledgetEmail_thenCorrect() {
+        User user = User.createWithDefaultCountry("John", "john@domain.com");
+        assertThat(user.getEmail()).isEqualTo("john@domain.com");
+    }
+    
+    @Test
+    public void givenUserIntanceCreatedWithcreateWithDefaultCountry_whenCalledgetCountry_thenCorrect() {
+        User user = User.createWithDefaultCountry("John", "john@domain.com");
+        assertThat(user.getCountry()).isEqualTo("Argentina");
+    }
+    
+    @Test
+    public void givenUserInstanceCreatedWithcreateWithInstantiationTime_whenCalledcreateWithInstantiationTime_thenCorrect() {
+        assertThat(User.createWithLoggedInstantiationTime("John", "john@domain.com", "Argentina")).isInstanceOf(User.class);
+    }
+    
+    @Test
+    public void givenUserInstanceCreatedWithgetSingletonIntance_whenCalledgetSingletonInstance_thenCorrect() {
+        User user1 = User.getSingletonInstance("John", "john@domain.com", "Argentina");
+        User user2 = User.getSingletonInstance("John", "john@domain.com", "Argentina");
+        assertThat(user1).isEqualTo(user2);
+    }
+}

core-java/src/test/java/com/baeldung/enums/PizzaUnitTest.java

@@ -76,25 +76,4 @@ public class PizzaUnitTest {
         pz.deliver();
         assertTrue(pz.getStatus() == Pizza.PizzaStatusEnum.DELIVERED);
     }   
-    
-    @Test
-    public void whenConvertedIntoEnum_thenGetsConvertedCorrectly() {
-        String pizzaEnumValue = "READY";
-        PizzaStatusEnum pizzaStatusEnum = PizzaStatusEnum.valueOf(pizzaEnumValue);
-        assertTrue(pizzaStatusEnum == PizzaStatusEnum.READY);
-    }
-    
-    @Test(expected = IllegalArgumentException.class)
-    public void whenConvertedIntoEnum_thenThrowsException() {
-        String pizzaEnumValue = "rEAdY";
-        PizzaStatusEnum pizzaStatusEnum = PizzaStatusEnum.valueOf(pizzaEnumValue);
-    }
-
-    @Test(expected = IllegalArgumentException.class)
-    public void givenInvalidEnumValueContentWiseAsString_whenConvertedIntoEnum_thenThrowsException() {
-        String pizzaEnumValue = "invalid";
-        PizzaStatusEnum pizzaStatusEnum = PizzaStatusEnum.valueOf(pizzaEnumValue);
-    }
-    
-
 }

core-java/src/test/java/com/baeldung/exceptionhandling/ExceptionsUnitTest.java

@@ -21,7 +21,7 @@ public class ExceptionsUnitTest {
     @Test
     public void loadAllPlayers() {
         assertThatThrownBy(() -> exceptions.loadAllPlayers(""))
-            .isInstanceOf(IOException.class);
+            .isInstanceOf(IllegalStateException.class);
     }
 
     @Test
@@ -72,12 +72,6 @@ public class ExceptionsUnitTest {
             .isInstanceOf(NullPointerException.class);
     }
     
-    @Test
-    public void throwAsGotoAntiPattern() {
-        assertThatThrownBy(() -> exceptions.throwAsGotoAntiPattern())
-            .isInstanceOf(MyException.class);
-    }
-    
     @Test
     public void getPlayerScoreSwallowingExceptionAntiPatternAlternative2() {
         assertThatThrownBy(() -> exceptions.getPlayerScoreSwallowingExceptionAntiPatternAlternative2(""))

core-java/src/test/java/org/baeldung/java/enums/PizzaUnitTest.java

@@ -1,81 +0,0 @@
-package org.baeldung.java.enums;
-
-import static junit.framework.TestCase.assertTrue;
-
-import java.util.ArrayList;
-import java.util.EnumMap;
-import java.util.List;
-
-import org.junit.Test;
-
-import com.baeldung.enums.Pizza;
-
-public class PizzaUnitTest {
-
-    @Test
-    public void givenPizaOrder_whenReady_thenDeliverable() {
-        Pizza testPz = new Pizza();
-        testPz.setStatus(Pizza.PizzaStatusEnum.READY);
-        assertTrue(testPz.isDeliverable());
-    }
-
-    @Test
-    public void givenPizaOrders_whenRetrievingUnDeliveredPzs_thenCorrectlyRetrieved() {
-        List<Pizza> pzList = new ArrayList<>();
-        Pizza pz1 = new Pizza();
-        pz1.setStatus(Pizza.PizzaStatusEnum.DELIVERED);
-
-        Pizza pz2 = new Pizza();
-        pz2.setStatus(Pizza.PizzaStatusEnum.ORDERED);
-
-        Pizza pz3 = new Pizza();
-        pz3.setStatus(Pizza.PizzaStatusEnum.ORDERED);
-
-        Pizza pz4 = new Pizza();
-        pz4.setStatus(Pizza.PizzaStatusEnum.READY);
-
-        pzList.add(pz1);
-        pzList.add(pz2);
-        pzList.add(pz3);
-        pzList.add(pz4);
-
-        List<Pizza> undeliveredPzs = Pizza.getAllUndeliveredPizzas(pzList);
-        assertTrue(undeliveredPzs.size() == 3);
-    }
-
-    @Test
-    public void givenPizaOrders_whenGroupByStatusCalled_thenCorrectlyGrouped() {
-
-        List<Pizza> pzList = new ArrayList<>();
-        Pizza pz1 = new Pizza();
-        pz1.setStatus(Pizza.PizzaStatusEnum.DELIVERED);
-
-        Pizza pz2 = new Pizza();
-        pz2.setStatus(Pizza.PizzaStatusEnum.ORDERED);
-
-        Pizza pz3 = new Pizza();
-        pz3.setStatus(Pizza.PizzaStatusEnum.ORDERED);
-
-        Pizza pz4 = new Pizza();
-        pz4.setStatus(Pizza.PizzaStatusEnum.READY);
-
-        pzList.add(pz1);
-        pzList.add(pz2);
-        pzList.add(pz3);
-        pzList.add(pz4);
-
-        EnumMap<Pizza.PizzaStatusEnum, List<Pizza>> map = Pizza.groupPizzaByStatus(pzList);
-        assertTrue(map.get(Pizza.PizzaStatusEnum.DELIVERED).size() == 1);
-        assertTrue(map.get(Pizza.PizzaStatusEnum.ORDERED).size() == 2);
-        assertTrue(map.get(Pizza.PizzaStatusEnum.READY).size() == 1);
-    }
-
-    @Test
-    public void givenPizaOrder_whenDelivered_thenPizzaGetsDeliveredAndStatusChanges() {
-        Pizza pz = new Pizza();
-        pz.setStatus(Pizza.PizzaStatusEnum.READY);
-        pz.deliver();
-        assertTrue(pz.getStatus() == Pizza.PizzaStatusEnum.DELIVERED);
-    }
-
-}

core-kotlin/src/main/kotlin/com/baeldung/builder/FoodOrder.kt

@@ -1,39 +1,22 @@
 package com.baeldung.builder
 
-class FoodOrder private constructor(builder: FoodOrder.Builder) {
-
-    val bread: String?
-    val condiments: String?
-    val meat: String?
+class FoodOrder(
+  val bread: String?,
+  val condiments: String?,
+  val meat: String?,
   val fish: String?
-
-    init {
-        this.bread = builder.bread
-        this.condiments = builder.condiments
-        this.meat = builder.meat
-        this.fish = builder.fish
-    }
-
-    class Builder {
-
-        var bread: String? = null
-            private set
-        var condiments: String? = null
-            private set
-        var meat: String? = null
-            private set
-        var fish: String? = null
-            private set
+) {
+    data class Builder(
+      var bread: String? = null,
+      var condiments: String? = null,
+      var meat: String? = null,
+      var fish: String? = null) {
 
         fun bread(bread: String) = apply { this.bread = bread }
-
         fun condiments(condiments: String) = apply { this.condiments = condiments }
-
         fun meat(meat: String) = apply { this.meat = meat }
-
         fun fish(fish: String) = apply { this.fish = fish }
-
-        fun build() = FoodOrder(this)
-
+        fun build() = FoodOrder(bread, condiments, meat, fish)
     }
 }
+

core-kotlin/src/main/kotlin/com/baeldung/builder/Main.kt

@@ -0,0 +1,9 @@
+package com.baeldung.builder
+
+fun main(args: Array<String>) {
+    FoodOrder.Builder()
+      .bread("bread")
+      .condiments("condiments")
+      .meat("meat")
+      .fish("bread").let { println(it) }
+}

core-kotlin/src/test/kotlin/com/baeldung/kotlin/CoroutinesTest.kt

@@ -103,7 +103,7 @@ class CoroutinesTest {
             //given
             val job = launch(CommonPool) {
                 while (isActive) {
-                    println("is working")
+                    //println("is working")
                 }
             }
 

core-kotlin/src/test/kotlin/com/baeldung/random/RandomNumberTest.kt

@@ -0,0 +1,55 @@
+
+import org.junit.jupiter.api.Test
+import java.util.concurrent.ThreadLocalRandom
+import kotlin.test.assertTrue
+
+class RandomNumberTest {
+
+    @Test
+    fun whenRandomNumberWithJavaUtilMath_thenResultIsBetween0And1() {
+        val randomNumber = Math.random()
+        assertTrue { randomNumber >=0 }
+        assertTrue { randomNumber <= 1 }
+    }
+
+    @Test
+    fun whenRandomNumberWithJavaThreadLocalRandom_thenResultsInDefaultRanges() {
+        val randomDouble = ThreadLocalRandom.current().nextDouble()
+        val randomInteger = ThreadLocalRandom.current().nextInt()
+        val randomLong = ThreadLocalRandom.current().nextLong()
+        assertTrue { randomDouble >= 0 }
+        assertTrue { randomDouble <= 1 }
+        assertTrue { randomInteger >= Integer.MIN_VALUE }
+        assertTrue { randomInteger <= Integer.MAX_VALUE }
+        assertTrue { randomLong >= Long.MIN_VALUE }
+        assertTrue { randomLong <= Long.MAX_VALUE }
+    }
+
+    @Test
+    fun whenRandomNumberWithKotlinJSMath_thenResultIsBetween0And1() {
+        val randomDouble = Math.random()
+        assertTrue { randomDouble >=0 }
+        assertTrue { randomDouble <= 1 }
+    }
+
+    @Test
+    fun whenRandomNumberWithKotlinNumberRange_thenResultInGivenRange() {
+        val randomInteger = (1..12).shuffled().first()
+        assertTrue { randomInteger >= 1 }
+        assertTrue { randomInteger <= 12 }
+    }
+
+    @Test
+    fun whenRandomNumberWithJavaThreadLocalRandom_thenResultsInGivenRanges() {
+        val randomDouble = ThreadLocalRandom.current().nextDouble(1.0, 10.0)
+        val randomInteger = ThreadLocalRandom.current().nextInt(1, 10)
+        val randomLong = ThreadLocalRandom.current().nextLong(1, 10)
+        assertTrue { randomDouble >= 1 }
+        assertTrue { randomDouble <= 10 }
+        assertTrue { randomInteger >= 1 }
+        assertTrue { randomInteger <= 10 }
+        assertTrue { randomLong >= 1 }
+        assertTrue { randomLong <= 10 }
+    }
+
+}

ethereum/pom.xml

@@ -214,7 +214,7 @@
         <web3j.core.version>3.3.1</web3j.core.version>
         <springframework.version>5.0.5.RELEASE</springframework.version>
         <spring.boot.version>1.5.6.RELEASE</spring.boot.version>
-        <mockito.version>1.10.19</mockito.version>
+        <mockito.version>2.21.0</mockito.version>
         <jackson-databind.version>2.5.0</jackson-databind.version>
         <hamcrest.version>1.3</hamcrest.version>
         <jackson.version>2.9.3</jackson.version>

guest/core-kotlin/.gitignore

@@ -0,0 +1,14 @@
+/bin/
+
+#ignore gradle
+.gradle/
+
+
+#ignore build and generated files
+build/
+node/
+out/
+
+#ignore installed node modules and package lock file
+node_modules/
+package-lock.json

guest/core-kotlin/pom.xml

@@ -0,0 +1,199 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-kotlin</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <groupId>com.stackify</groupId>
+    <packaging>jar</packaging>
+
+    <repositories>
+        <repository>
+            <id>jcenter</id>
+            <url>http://jcenter.bintray.com</url>
+        </repository>
+    </repositories>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-runner</artifactId>
+            <version>${junit.platform.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib</artifactId>
+            <version>${kotlin-stdlib.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib-jdk8</artifactId>
+            <version>${kotlin-stdlib.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-test-junit</artifactId>
+            <version>${kotlin-test-junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-reflect</artifactId>
+            <version>${kotlin-reflect.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.spek</groupId>
+            <artifactId>spek-api</artifactId>
+            <version>1.1.5</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.spek</groupId>
+            <artifactId>spek-subject-extension</artifactId>
+            <version>1.1.5</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.spek</groupId>
+            <artifactId>spek-junit-platform-engine</artifactId>
+            <version>1.1.5</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.nhaarman</groupId>
+            <artifactId>mockito-kotlin</artifactId>
+            <version>${mockito-kotlin.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-compiler-plugin</artifactId>
+            <version>${maven-compiler-plugin.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-failsafe-plugin</artifactId>
+            <version>${maven-failsafe-plugin.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-maven-plugin</artifactId>
+            <version>${kotlin-maven-plugin.version}</version>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.jetbrains.kotlin</groupId>
+                <artifactId>kotlin-maven-plugin</artifactId>
+                <version>${kotlin-maven-plugin.version}</version>
+                <executions>
+                    <execution>
+                        <id>compile</id>
+                        <goals>
+                            <goal>compile</goal>
+                        </goals>
+                        <configuration>
+                            <sourceDirs>
+                                <sourceDir>${project.basedir}/src/main/kotlin</sourceDir>
+                            </sourceDirs>
+                        </configuration>
+                    </execution>
+                    <execution>
+                        <id>test-compile</id>
+                        <goals>
+                            <goal>test-compile</goal>
+                        </goals>
+                        <configuration>
+                            <sourceDirs>
+                                <sourceDir>${project.basedir}/src/test/kotlin</sourceDir>
+                            </sourceDirs>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>${maven-compiler-plugin.version}</version>
+                <configuration>
+                    <source>${java.version}</source>
+                    <target>${java.version}</target>
+                </configuration>
+                <executions>
+                    <!-- Replacing default-compile as it is treated specially 
+                        by maven -->
+                    <execution>
+                        <id>default-compile</id>
+                        <phase>none</phase>
+                    </execution>
+                    <!-- Replacing default-testCompile as it is treated specially 
+                        by maven -->
+                    <execution>
+                        <id>default-testCompile</id>
+                        <phase>none</phase>
+                    </execution>
+                    <execution>
+                        <id>java-compile</id>
+                        <phase>compile</phase>
+                        <goals>
+                            <goal>compile</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <artifactId>maven-failsafe-plugin</artifactId>
+                <version>${maven-failsafe-plugin.version}</version>
+                <dependencies>
+                    <dependency>
+                        <groupId>org.junit.platform</groupId>
+                        <artifactId>junit-platform-surefire-provider</artifactId>
+                        <version>${junit.platform.version}</version>
+                    </dependency>
+                </dependencies>
+                <executions>
+                    <execution>
+                        <id>junit5</id>
+                        <goals>
+                            <goal>integration-test</goal>
+                            <goal>verify</goal>
+                        </goals>
+                        <configuration>
+                            <includes>
+                                <include>**/*Test5.java</include>
+                            </includes>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <maven-failsafe-plugin.version>2.22.0</maven-failsafe-plugin.version>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <kotlin-maven-plugin.version>1.2.60</kotlin-maven-plugin.version>
+        <kotlin-test-junit.version>1.2.51</kotlin-test-junit.version>
+        <kotlin-stdlib.version>1.2.51</kotlin-stdlib.version>
+        <kotlin-reflect.version>1.2.51</kotlin-reflect.version>
+        <kotlinx.version>0.22.5</kotlinx.version>
+        <mockito-kotlin.version>1.5.0</mockito-kotlin.version>
+        <commons-math3.version>3.6.1</commons-math3.version>
+        <junit.platform.version>1.0.0</junit.platform.version>
+        <junit.vintage.version>5.2.0</junit.vintage.version>
+        <assertj.version>3.10.0</assertj.version>
+        <maven-compiler-plugin.version>3.7.0</maven-compiler-plugin.version>
+    </properties>
+
+</project>

guest/core-kotlin/src/test/kotlin/com/baeldung/kotlinvsjava/ExceptionsTest.kt

@@ -24,7 +24,7 @@ class ExceptionsTest {
     fun givenANullString_whenUsingElvisOperator_thenExceptionIsThrown() {
         val sampleString: String? = null
 
-        val length: Int = sampleString?.length ?: throw IllegalArgumentException("String must not be null")
+        sampleString?.length ?: throw IllegalArgumentException("String must not be null")
     }
 
     private fun funThrowingException(): Nothing {

java-strings/README.md

@@ -0,0 +1,27 @@
+=========
+
+## Java Strings Cookbooks and Examples
+
+### Relevant Articles: 
+- [String Operations with Java Streams](http://www.baeldung.com/java-stream-operations-on-strings)
+- [Converting String to Stream of chars](http://www.baeldung.com/java-string-to-stream)
+- [Java 8 StringJoiner](http://www.baeldung.com/java-string-joiner)
+- [Image to Base64 String Conversion](http://www.baeldung.com/java-base64-image-string)
+- [Java – Generate Random String](http://www.baeldung.com/java-random-string)
+- [Convert char to String in Java](http://www.baeldung.com/java-convert-char-to-string)
+- [Convert String to int or Integer in Java](http://www.baeldung.com/java-convert-string-to-int-or-integer)
+- [How to Convert String to different data types in Java](http://www.baeldung.com/java-string-conversions)
+- [Converting Strings to Enums in Java](http://www.baeldung.com/java-string-to-enum)
+- [Quick Guide to the Java StringTokenizer](http://www.baeldung.com/java-stringtokenizer)
+- [Count Occurrences of a Char in a String](http://www.baeldung.com/java-count-chars)
+- [Split a String in Java](http://www.baeldung.com/java-split-string)
+- [How to Remove the Last Character of a String?](http://www.baeldung.com/java-remove-last-character-of-string)
+- [CharSequence vs. String in Java](http://www.baeldung.com/java-char-sequence-string)
+- [StringBuilder and StringBuffer in Java](http://www.baeldung.com/java-string-builder-string-buffer)
+- [Guide to Java String Pool](http://www.baeldung.com/java-string-pool)
+- [Check if a String is a Palindrome](http://www.baeldung.com/java-palindrome)
+- [Comparing Strings in Java](http://www.baeldung.com/java-compare-strings)
+- [Check If a String Is Numeric in Java](http://www.baeldung.com/java-check-string-number)
+- [Why Use char[] Array Over a String for Storing Passwords in Java?](http://www.baeldung.com/java-storing-passwords)
+- [Convert a String to Title Case](http://www.baeldung.com/java-string-title-case)
+- [Compact Strings in Java 9](http://www.baeldung.com/java-9-compact-string)

java-strings/pom.xml

@@ -0,0 +1,107 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung</groupId>
+    <artifactId>java-strings</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    <name>java-strings</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-java</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../parent-java</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>${commons-io.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>${log4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>commons-codec</groupId>
+            <artifactId>commons-codec</artifactId>
+            <version>${commons-codec.version}</version>
+        </dependency>
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${jmh-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.ibm.icu</groupId>
+            <artifactId>icu4j</artifactId>
+            <version>${icu4j.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>java-strings</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-dependency-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <id>copy-dependencies</id>
+                        <phase>prepare-package</phase>
+                        <goals>
+                            <goal>copy-dependencies</goal>
+                        </goals>
+                        <configuration>
+                            <outputDirectory>${project.build.directory}/libs</outputDirectory>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.1</version>
+                <configuration>
+                    <source>1.8</source>
+                    <target>1.8</target>
+                    <compilerArgument>-parameters</compilerArgument>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <!-- util -->
+        <commons-lang3.version>3.5</commons-lang3.version>
+        <commons-codec.version>1.10</commons-codec.version>
+        <!-- testing -->
+        <assertj.version>3.6.1</assertj.version>
+        <jmh-core.version>1.19</jmh-core.version>
+        <icu4j.version>61.1</icu4j.version>
+    </properties>
+
+</project>

java-strings/src/main/java/com/baeldung/enums/PizzaStatusEnum.java

@@ -0,0 +1,44 @@
+package com.baeldung.enums;
+
+public enum PizzaStatusEnum {
+    ORDERED(5) {
+        @Override
+        public boolean isOrdered() {
+            return true;
+        }
+    },
+    READY(2) {
+        @Override
+        public boolean isReady() {
+            return true;
+        }
+    },
+    DELIVERED(0) {
+        @Override
+        public boolean isDelivered() {
+            return true;
+        }
+    };
+
+    private int timeToDelivery;
+
+    public boolean isOrdered() {
+        return false;
+    }
+
+    public boolean isReady() {
+        return false;
+    }
+
+    public boolean isDelivered() {
+        return false;
+    }
+
+    public int getTimeToDelivery() {
+        return timeToDelivery;
+    }
+
+    PizzaStatusEnum(int timeToDelivery) {
+        this.timeToDelivery = timeToDelivery;
+    }
+}

java-strings/src/main/java/com/baeldung/string/TitleCaseConverter.java

@@ -1,12 +1,13 @@
 package com.baeldung.string;
 
-import com.ibm.icu.lang.UCharacter;
-import com.ibm.icu.text.BreakIterator;
-import org.apache.commons.lang.WordUtils;
-
 import java.util.Arrays;
 import java.util.stream.Collectors;
 
+import org.apache.commons.lang3.text.WordUtils;
+
+import com.ibm.icu.lang.UCharacter;
+import com.ibm.icu.text.BreakIterator;
+
 public class TitleCaseConverter {
 
     private static final String WORD_SEPARATOR = " ";

java-strings/src/main/resources/logback.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

java-strings/src/test/java/com/baeldung/enums/PizzaUnitTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.enums;
+
+import static junit.framework.TestCase.assertTrue;
+
+import org.junit.Test;
+
+public class PizzaUnitTest {
+    
+    @Test
+    public void whenConvertedIntoEnum_thenGetsConvertedCorrectly() {
+        String pizzaEnumValue = "READY";
+        PizzaStatusEnum pizzaStatusEnum = PizzaStatusEnum.valueOf(pizzaEnumValue);
+        assertTrue(pizzaStatusEnum == PizzaStatusEnum.READY);
+    }
+    
+    @Test(expected = IllegalArgumentException.class)
+    public void whenConvertedIntoEnum_thenThrowsException() {
+        String pizzaEnumValue = "rEAdY";
+        PizzaStatusEnum pizzaStatusEnum = PizzaStatusEnum.valueOf(pizzaEnumValue);
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void givenInvalidEnumValueContentWiseAsString_whenConvertedIntoEnum_thenThrowsException() {
+        String pizzaEnumValue = "invalid";
+        PizzaStatusEnum pizzaStatusEnum = PizzaStatusEnum.valueOf(pizzaEnumValue);
+    }
+}

java-strings/src/test/java/com/baeldung/java/countingChars/CountCharsExampleUnitTest.java

@@ -1,13 +1,14 @@
 package com.baeldung.java.countingChars;
 
-import com.google.common.base.CharMatcher;
-import org.apache.commons.lang.StringUtils;
-import org.junit.Test;
+import static org.junit.Assert.assertEquals;
 
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
-import static org.junit.Assert.assertEquals;
+import org.apache.commons.lang3.StringUtils;
+import org.junit.Test;
+
+import com.google.common.base.CharMatcher;
 
 
 /***

java-strings/src/test/java/com/baeldung/string/SplitUnitTest.java

@@ -1,12 +1,13 @@
 package com.baeldung.string;
 
-import com.google.common.base.Splitter;
-import org.apache.commons.lang.StringUtils;
-import org.junit.Test;
+import static org.assertj.core.api.Assertions.assertThat;
 
 import java.util.List;
 
-import static org.assertj.core.api.Assertions.assertThat;
+import org.apache.commons.lang3.StringUtils;
+import org.junit.Test;
+
+import com.google.common.base.Splitter;
 
 public class SplitUnitTest {