Merge remote-tracking branch 'upstream/master'

algorithms-miscellaneous-6/README.md

@@ -7,4 +7,6 @@
 - [Efficiently Merge Sorted Java Sequences](https://www.baeldung.com/java-merge-sorted-sequences)
 - [Introduction to Greedy Algorithms with Java](https://www.baeldung.com/java-greedy-algorithms)
 - [The Caesar Cipher in Java](https://www.baeldung.com/java-caesar-cipher)
+- [Implementing a 2048 Solver in Java](https://www.baeldung.com/2048-java-solver)
+- [Finding Top K Elements in an Array](https://www.baeldung.com/java-array-top-elements)
 - More articles: [[<-- prev]](/../algorithms-miscellaneous-5)

apache-shiro/README.md

@@ -6,4 +6,4 @@ This module contains articles about Apache Shiro
 
 - [Introduction to Apache Shiro](https://www.baeldung.com/apache-shiro)
 - [Permissions-Based Access Control with Apache Shiro](https://www.baeldung.com/apache-shiro-access-control)
-
+- [Spring Security vs Apache Shiro](https://www.baeldung.com/spring-security-vs-apache-shiro)

core-groovy/README.md

@@ -13,4 +13,5 @@ This module contains articles about core Groovy concepts
 - [Converting a String to a Date in Groovy](https://www.baeldung.com/groovy-string-to-date)
 - [Guide to I/O in Groovy](https://www.baeldung.com/groovy-io)
 - [Convert String to Integer in Groovy](https://www.baeldung.com/groovy-convert-string-to-integer)
+- [Groovy Variable Scope](https://www.baeldung.com/groovy/variable-scope)
 - [[More -->]](/core-groovy-2)

core-java-modules/core-java-11/README.md

@@ -8,7 +8,7 @@ This module contains articles about Java 11 core features
 - [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)
-- [Exploring the New HTTP Client in Java 9 and 11](https://www.baeldung.com/java-9-http-client)
+- [Exploring the New HTTP Client in Java](https://www.baeldung.com/java-9-http-client)
 - [An Introduction to Epsilon GC: A No-Op Experimental Garbage Collector](https://www.baeldung.com/jvm-epsilon-gc-garbage-collector)
 - [Guide to jlink](https://www.baeldung.com/jlink)
 - [Negate a Predicate Method Reference with Java 11](https://www.baeldung.com/java-negate-predicate-method-reference)

core-java-modules/core-java-9-jigsaw/src/simple-modules/main.app/com/baeldung/modules/main/MainApp.java

@@ -1,12 +1,15 @@
 package com.baeldung.modules.main;
 
+import com.baeldung.modules.hello.HelloInterface;
 import com.baeldung.modules.hello.HelloModules;
+import java.util.ServiceLoader;
 
 public class MainApp {
     public static void main(String[] args) {
         HelloModules.doSomething();
-
-        HelloModules module = new HelloModules();
-        module.sayHello();
+        
+        Iterable<HelloInterface> services = ServiceLoader.load(HelloInterface.class);
+        HelloInterface service = services.iterator().next();
+        service.sayHello();
     }
 }

core-java-modules/core-java-9-new-features/README.md

@@ -13,3 +13,4 @@ This module contains articles about core Java features that have been introduced
 - [Java 9 Platform Logging API](https://www.baeldung.com/java-9-logging-api)
 - [Java 9 Reactive Streams](https://www.baeldung.com/java-9-reactive-streams)
 - [Multi-Release JAR Files with Maven](https://www.baeldung.com/maven-multi-release-jars)
+- [The Difference between RxJava API and the Java 9 Flow API](https://www.baeldung.com/rxjava-vs-java-flow-api)

core-java-modules/core-java-9/README.md

@@ -9,3 +9,4 @@ This module contains articles about Java 9 core features
 - [Iterate Through a Range of Dates in Java](https://www.baeldung.com/java-iterate-date-range)
 - [Initialize a HashMap in Java](https://www.baeldung.com/java-initialize-hashmap)
 - [Immutable ArrayList in Java](https://www.baeldung.com/java-immutable-list)
+- [Easy Ways to Write a Java InputStream to an OutputStream](https://www.baeldung.com/java-inputstream-to-outputstream)

core-java-modules/core-java-arrays-guides/README.md

@@ -5,4 +5,4 @@ This module contains complete guides about arrays in Java
 ### Relevant Articles: 
 - [Arrays in Java: A Reference Guide](https://www.baeldung.com/java-arrays-guide)
 - [Guide to the java.util.Arrays Class](https://www.baeldung.com/java-util-arrays)
-- [What is [Ljava.lang.Object;?]](https://www.baeldung.com/java-tostring-array)
+- [What is \[Ljava.lang.Object;?](https://www.baeldung.com/java-tostring-array)

core-java-modules/core-java-collections-3/README.md

@@ -3,6 +3,7 @@
 ## Core Java Collections Cookbooks and Examples
 
 ### Relevant Articles: 
+
 - [Time Comparison of Arrays.sort(Object[]) and Arrays.sort(int[])](https://www.baeldung.com/arrays-sortobject-vs-sortint)
 - [Java ArrayList vs Vector](https://www.baeldung.com/java-arraylist-vs-vector)
 - [Differences Between HashMap and Hashtable](https://www.baeldung.com/hashmap-hashtable-differences)
@@ -10,3 +11,4 @@
 - [Performance of contains() in a HashSet vs ArrayList](https://www.baeldung.com/java-hashset-arraylist-contains-performance)
 - [Fail-Safe Iterator vs Fail-Fast Iterator](https://www.baeldung.com/java-fail-safe-vs-fail-fast-iterator)
 - [Quick Guide to the Java Stack](https://www.baeldung.com/java-stack)
+- [Convert an Array of Primitives to a List](https://www.baeldung.com/java-primitive-array-to-list)

core-java-modules/core-java-collections-3/pom.xml

@@ -16,6 +16,11 @@
     </parent>
 
     <dependencies>
+        <dependency>
+            <groupId>org.openjdk.jol</groupId>
+            <artifactId>jol-core</artifactId>
+            <version>${jol-core.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.openjdk.jmh</groupId>
             <artifactId>jmh-core</artifactId>
@@ -37,6 +42,7 @@
     <properties>
         <openjdk.jmh.version>1.19</openjdk.jmh.version>
         <assertj.version>3.11.1</assertj.version>
+        <jol-core.version>0.10</jol-core.version>
     </properties>
 
 </project>

core-java-modules/core-java-collections-3/src/test/java/com/baeldung/collections/bitset/BitSetUnitTest.java

@@ -0,0 +1,178 @@
+package com.baeldung.collections.bitset;
+
+import org.junit.Test;
+import org.openjdk.jol.info.ClassLayout;
+import org.openjdk.jol.info.GraphLayout;
+
+import java.util.BitSet;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class BitSetUnitTest {
+
+    @Test
+    public void givenBoolArray_whenMemoryLayout_thenConsumeMoreThanOneBit() {
+        boolean[] bits = new boolean[1024 * 1024];
+
+        System.out.println(ClassLayout.parseInstance(bits).toPrintable());
+    }
+
+    @Test
+    public void givenBitSet_whenMemoryLayout_thenConsumeOneBitPerFlag() {
+        BitSet bitSet = new BitSet(1024 * 1024);
+
+        System.out.println(GraphLayout.parseInstance(bitSet).toPrintable());
+    }
+
+    @Test
+    public void givenBitSet_whenSetting_thenShouldBeTrue() {
+        BitSet bitSet = new BitSet();
+
+        bitSet.set(10);
+        assertThat(bitSet.get(10)).isTrue();
+
+        bitSet.set(20, 30);
+        for (int i = 20; i <= 29; i++) {
+            assertThat(bitSet.get(i)).isTrue();
+        }
+        assertThat(bitSet.get(30)).isFalse();
+
+        bitSet.set(10, false);
+        assertThat(bitSet.get(10)).isFalse();
+
+        bitSet.set(20, 30, false);
+        for (int i = 20; i <= 30; i++) {
+            assertThat(bitSet.get(i)).isFalse();
+        }
+    }
+
+    @Test
+    public void givenBitSet_whenClearing_thenShouldBeFalse() {
+        BitSet bitSet = new BitSet();
+        bitSet.set(42);
+        assertThat(bitSet.get(42)).isTrue();
+
+        bitSet.clear(42);
+        assertThat(bitSet.get(42)).isFalse();
+
+        bitSet.set(10, 20);
+        for (int i = 10; i < 20; i++) {
+            assertThat(bitSet.get(i)).isTrue();
+        }
+
+        bitSet.clear(10, 20);
+        for (int i = 10; i < 20; i++) {
+            assertThat(bitSet.get(i)).isFalse();
+        }
+
+        bitSet.set(10, 20);
+        bitSet.clear();
+        for (int i = 0; i < 100; i++) {
+            assertThat(bitSet.get(i)).isFalse();
+        }
+    }
+
+    @Test
+    public void givenBitSet_whenGettingElements_thenShouldReturnRequestedBits() {
+        BitSet bitSet = new BitSet();
+        bitSet.set(42);
+
+        assertThat(bitSet.get(42)).isTrue();
+        assertThat(bitSet.get(43)).isFalse();
+
+        bitSet.set(10, 20);
+        BitSet newBitSet = bitSet.get(10, 20);
+        for (int i = 0; i < 10; i++) {
+            assertThat(newBitSet.get(i)).isTrue();
+        }
+    }
+
+    @Test
+    public void givenBitSet_whenFlip_thenTogglesTrueToFalseAndViceVersa() {
+        BitSet bitSet = new BitSet();
+        bitSet.set(42);
+        bitSet.flip(42);
+        assertThat(bitSet.get(42)).isFalse();
+
+        bitSet.flip(12);
+        assertThat(bitSet.get(12)).isTrue();
+
+        bitSet.flip(30, 40);
+        for (int i = 30; i < 40; i++) {
+            assertThat(bitSet.get(i)).isTrue();
+        }
+    }
+
+    @Test
+    public void givenBitSet_whenGettingTheSize_thenReturnsTheSize() {
+        BitSet defaultBitSet = new BitSet();
+        assertThat(defaultBitSet.size()).isEqualTo(64);
+
+        BitSet bitSet = new BitSet(1024);
+        assertThat(bitSet.size()).isEqualTo(1024);
+
+        assertThat(bitSet.cardinality()).isEqualTo(0);
+        bitSet.set(10, 30);
+        assertThat(bitSet.cardinality()).isEqualTo(30 - 10);
+
+        assertThat(bitSet.length()).isEqualTo(30);
+        bitSet.set(100);
+        assertThat(bitSet.length()).isEqualTo(101);
+
+        assertThat(bitSet.isEmpty()).isFalse();
+        bitSet.clear();
+        assertThat(bitSet.isEmpty()).isTrue();
+    }
+
+    @Test
+    public void givenBitSet_whenSetOperations_thenShouldReturnAnotherBitSet() {
+        BitSet first = new BitSet();
+        first.set(5, 10);
+
+        BitSet second = new BitSet();
+        second.set(7, 15);
+
+        assertThat(first.intersects(second)).isTrue();
+
+        first.and(second);
+        assertThat(first.get(7)).isTrue();
+        assertThat(first.get(8)).isTrue();
+        assertThat(first.get(9)).isTrue();
+        assertThat(first.get(10)).isFalse();
+
+        first.clear();
+        first.set(5, 10);
+
+        first.xor(second);
+        for (int i = 5; i < 7; i++) {
+            assertThat(first.get(i)).isTrue();
+        }
+        for (int i = 10; i < 15; i++) {
+            assertThat(first.get(i)).isTrue();
+        }
+    }
+
+    @Test
+    public void givenBitSet_whenStream_thenStreamsAllSetBits() {
+        BitSet bitSet = new BitSet();
+        bitSet.set(15, 25);
+
+        bitSet.stream().forEach(System.out::println);
+        assertThat(bitSet.stream().count()).isEqualTo(10);
+    }
+
+    @Test
+    public void givenBitSet_whenNextOrPrev_thenReturnsTheNextOrPrevClearOrSetBit() {
+        BitSet bitSet = new BitSet();
+        bitSet.set(15, 25);
+
+        assertThat(bitSet.nextSetBit(13)).isEqualTo(15);
+        assertThat(bitSet.nextSetBit(25)).isEqualTo(-1);
+
+        assertThat(bitSet.nextClearBit(23)).isEqualTo(25);
+
+        assertThat(bitSet.previousClearBit(24)).isEqualTo(14);
+        assertThat(bitSet.previousSetBit(29)).isEqualTo(24);
+        assertThat(bitSet.previousSetBit(14)).isEqualTo(-1);
+    }
+}

core-java-modules/core-java-concurrency-advanced-3/README.md

@@ -15,4 +15,5 @@ This module contains articles about advanced topics about multithreading with co
 - [The ABA Problem in Concurrency](https://www.baeldung.com/cs/aba-concurrency)
 - [Introduction to Lock-Free Data Structures](https://www.baeldung.com/lock-free-programming)
 - [Introduction to Exchanger in Java](https://www.baeldung.com/java-exchanger)
+- [Why Not To Start A Thread In The Constructor?](https://www.baeldung.com/java-thread-constructor)
 - [[<-- previous]](/core-java-modules/core-java-concurrency-advanced-2)

core-java-modules/core-java-concurrency-basic-2/README.md

@@ -3,10 +3,12 @@
 This module contains articles about basic Java concurrency
 
 ### Relevant Articles: 
+
 - [How to Delay Code Execution in Java](https://www.baeldung.com/java-delay-code-execution)
 - [wait and notify() Methods in Java](https://www.baeldung.com/java-wait-notify)
 - [Difference Between Wait and Sleep in Java](https://www.baeldung.com/java-wait-and-sleep)
 - [Guide to the Synchronized Keyword in Java](https://www.baeldung.com/java-synchronized)
 - [Life Cycle of a Thread in Java](https://www.baeldung.com/java-thread-lifecycle)
 - [Guide to AtomicMarkableReference](https://www.baeldung.com/java-atomicmarkablereference)
+- [Why are Local Variables Thread-Safe in Java](https://www.baeldung.com/java-local-variables-thread-safe)
 - [[<-- Prev]](/core-java-modules/core-java-concurrency-basic)

core-java-modules/core-java-console/src/main/java/com/baeldung/consoleout/ConsoleAndOut.java

@@ -0,0 +1,31 @@
+package com.baeldung.consoleout;
+
+import java.io.Console;
+
+public class ConsoleAndOut {
+    public static void main(String[] args) {
+        try {
+            printConsoleObject();
+            readPasswordFromConsole();
+        } catch (Exception ex) {
+            // Eating NullPointerExcpetion which will occur when this 
+            // program will be run from mediums other than console
+        }
+        printSysOut();    
+    }
+
+    static void printConsoleObject() {
+        Console console = System.console();
+        console.writer().print(console);
+    }
+
+    static void readPasswordFromConsole() {
+        Console console = System.console();
+        char[] password = console.readPassword("Enter password: ");
+        console.printf(String.valueOf(password));
+    }
+    
+    static void printSysOut() {
+        System.out.println(System.out);
+    }
+}

core-java-modules/core-java-console/src/test/java/com/baeldung/consoleout/ConsoleAndOutUnitTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.consoleout;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+class ConsoleAndOutUnitTest {
+
+    @Test
+    void whenRetreivingConsole_thenPrintConsoleObject() {
+        assertThrows(NullPointerException.class, () -> {
+            ConsoleAndOut.printConsoleObject();  
+        });
+    }
+    
+    @Test
+    void whenReadingPassword_thenReadPassword() {
+        assertThrows(NullPointerException.class, () -> {
+            ConsoleAndOut.readPasswordFromConsole();  
+        });
+    }
+    
+    @Test
+    void whenRetrievingSysOut_thenPrintSysOutObject() {
+        ConsoleAndOut.printSysOut();
+    }
+}

core-java-modules/core-java-date-operations-2/README.md

@@ -2,6 +2,7 @@
 This module contains articles about date operations in Java.
 
 ### Relevant Articles:
+
 - [Get the Current Date Prior to Java 8](https://www.baeldung.com/java-get-the-current-date-legacy)
 - [Skipping Weekends While Adding Days to LocalDate in Java 8](https://www.baeldung.com/java-localdate-add-days-skip-weekends)
 - [Checking If Two Java Dates Are on the Same Day](https://www.baeldung.com/java-check-two-dates-on-same-day)
@@ -9,4 +10,5 @@ This module contains articles about date operations in Java.
 - [How to Set the JVM Time Zone](https://www.baeldung.com/java-jvm-time-zone)
 - [How to determine day of week by passing specific date in Java?](https://www.baeldung.com/java-get-day-of-week)
 - [Finding Leap Years in Java](https://www.baeldung.com/java-leap-year)
+- [Getting the Week Number From Any Date](https://www.baeldung.com/java-get-week-number)
 - [[<-- Prev]](/core-java-modules/core-java-date-operations-1)

core-java-modules/core-java-exceptions-2/README.md

@@ -12,3 +12,5 @@ This module contains articles about core java exceptions
 - [Java – Try with Resources](https://www.baeldung.com/java-try-with-resources)
 - [Java Global Exception Handler](https://www.baeldung.com/java-global-exception-handler)
 - [How to Find an Exception’s Root Cause in Java](https://www.baeldung.com/java-exception-root-cause)
+- [Java IOException “Too many open files”](https://www.baeldung.com/java-too-many-open-files)
+- [When Does Java Throw the ExceptionInInitializerError?](https://www.baeldung.com/java-exceptionininitializererror)

core-java-modules/core-java-io-2/README.md

@@ -13,4 +13,4 @@ This module contains articles about core Java input and output (IO)
 - [How to Copy a File with Java](https://www.baeldung.com/java-copy-file)
 - [Create a Directory in Java](https://www.baeldung.com/java-create-directory) 
 - [Java IO vs NIO](https://www.baeldung.com/java-io-vs-nio)
-- [[<-- Prev]](/core-java-modules/core-java-io)
+- [[<-- Prev]](/core-java-modules/core-java-io)[[More -->]](/core-java-modules/core-java-io-3)

core-java-modules/core-java-io-3/README.md

@@ -0,0 +1,9 @@
+## Core Java IO
+
+This module contains articles about core Java input and output (IO)
+
+### Relevant Articles: 
+
+- [Java – Create a File](https://www.baeldung.com/java-how-to-create-a-file)
+- [Check If a Directory Is Empty in Java](https://www.baeldung.com/java-check-empty-directory)
+- [[<-- Prev]](/core-java-modules/core-java-io-2)

core-java-modules/core-java-io-3/pom.xml

@@ -0,0 +1,59 @@
+<?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-java-io-3</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-io-3</name>
+    <packaging>jar</packaging>
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../</relativePath>
+    </parent>
+
+    <dependencies>
+        <!-- utils -->
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>${guava.version}</version>
+        </dependency>
+        <!-- utils -->
+        <dependency>
+            <groupId>commons-io</groupId>
+            <artifactId>commons-io</artifactId>
+            <version>${commons-io.version}</version>
+        </dependency>
+        <!-- logging -->
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>${log4j.version}</version>
+        </dependency>
+        <dependency> <!-- needed to bridge to slf4j for projects that use the log4j APIs directly -->
+            <groupId>org.slf4j</groupId>
+            <artifactId>log4j-over-slf4j</artifactId>
+            <version>${org.slf4j.version}</version>
+        </dependency>
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+    </dependencies>
+
+    <build>
+    </build>
+
+    <properties>
+        <assertj.version>3.6.1</assertj.version>
+    </properties>
+
+</project>

core-java-modules/core-java-io-3/src/test/java/com/baeldung/createfile/CreateFileUnitTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.createfile;
+
+import org.apache.commons.io.FileUtils;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class CreateFileUnitTest {
+
+    private final String FILE_NAME = "src/test/resources/fileToCreate.txt";
+
+    @AfterEach
+    @BeforeEach
+    public void cleanUpFiles() {
+        File targetFile = new File(FILE_NAME);
+        targetFile.delete();
+    }
+
+    @Test
+    public void givenUsingNio_whenCreatingFile_thenCorrect() throws IOException {
+        Path newFilePath = Paths.get(FILE_NAME);
+        Files.createFile(newFilePath);
+    }
+
+    @Test
+    public void givenUsingFile_whenCreatingFile_thenCorrect() throws IOException {
+        File newFile = new File(FILE_NAME);
+        boolean success = newFile.createNewFile();
+        assertTrue(success);
+    }
+
+    @Test
+    public void givenUsingGuava_whenCreatingFile_thenCorrect() throws IOException {
+        com.google.common.io.Files.touch(new File(FILE_NAME));
+    }
+
+    @Test
+    public void givenUsingCommonsIo_whenCreatingFile_thenCorrect() throws IOException {
+        FileUtils.touch(new File(FILE_NAME));
+    }
+
+}

core-java-modules/core-java-io-3/src/test/java/com/baeldung/emptiness/DirectoryEmptinessUnitTest.java

@@ -0,0 +1,63 @@
+package com.baeldung.emptiness;
+
+import org.junit.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.DirectoryStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.stream.Stream;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class DirectoryEmptinessUnitTest {
+
+    @Test
+    public void givenPath_whenInvalid_thenReturnsFalse() throws IOException {
+        assertThat(isEmpty(Paths.get("invalid-addr"))).isFalse();
+    }
+
+    @Test
+    public void givenPath_whenNotDirectory_thenReturnsFalse() throws IOException {
+        Path aFile = Paths.get(getClass().getResource("/notDir.txt").getPath());
+        assertThat(isEmpty(aFile)).isFalse();
+    }
+
+    @Test
+    public void givenPath_whenNotEmptyDir_thenReturnsFalse() throws IOException {
+        Path currentDir = new File("").toPath().toAbsolutePath();
+        assertThat(isEmpty(currentDir)).isFalse();
+    }
+
+    @Test
+    public void givenPath_whenIsEmpty_thenReturnsTrue() throws Exception {
+        Path path = Files.createTempDirectory("baeldung-empty");
+        assertThat(isEmpty(path)).isTrue();
+    }
+
+    private static boolean isEmpty(Path path) throws IOException {
+        if (Files.isDirectory(path)) {
+            try (DirectoryStream<Path> directory = Files.newDirectoryStream(path)) {
+                return !directory.iterator().hasNext();
+            }
+        }
+
+        return false;
+    }
+
+    private static boolean isEmpty2(Path path) throws IOException {
+        if (Files.isDirectory(path)) {
+            try (Stream<Path> entries = Files.list(path)) {
+                return !entries.findFirst().isPresent();
+            }
+        }
+
+        return false;
+    }
+
+    private static boolean isEmptyInefficient(Path path) {
+        return path.toFile().listFiles().length == 0;
+    }
+}

core-java-modules/core-java-io-apis/README.md

@@ -7,7 +7,6 @@ This module contains articles about core Java input/output(IO) APIs.
 - [A Guide to the Java FileReader Class](https://www.baeldung.com/java-filereader)
 - [The Java File Class](https://www.baeldung.com/java-io-file)
 - [Java FileWriter](https://www.baeldung.com/java-filewriter)
-- [Differences Between the Java WatchService API and the Apache Commons IO Monitor Library](https://www.baeldung.com/java-watchservice-vs-apache-commons-io-monitor-library)
 - [Comparing getPath(), getAbsolutePath(), and getCanonicalPath() in Java](https://www.baeldung.com/java-path)
 - [Quick Use of FilenameFilter](https://www.baeldung.com/java-filename-filter)
 - [Guide to BufferedReader](https://www.baeldung.com/java-buffered-reader)

core-java-modules/core-java-jvm-2/README.md

@@ -8,4 +8,6 @@ This module contains articles about working with the Java Virtual Machine (JVM).
 - [Measuring Object Sizes in the JVM](https://www.baeldung.com/jvm-measuring-object-sizes)
 - [Adding Shutdown Hooks for JVM Applications](https://www.baeldung.com/jvm-shutdown-hooks)
 - [boolean and boolean[] Memory Layout in the JVM](https://www.baeldung.com/jvm-boolean-memory-layout)
-- More articles: [[<-- prev]](/core-java-modules/core-java-jvm)
+- [Where Is the Array Length Stored in JVM?](https://www.baeldung.com/java-jvm-array-length)
+- [Memory Address of Objects in Java](https://www.baeldung.com/java-object-memory-address)
+- More articles: [[<-- prev]](/core-java-modules/core-java-jvm)

core-java-modules/core-java-lang-3/README.md

@@ -2,4 +2,6 @@
 
 This module contains articles about core features in the Java language
 
+- [Class.isInstance vs Class.isAssignableFrom](https://www.baeldung.com/java-isinstance-isassignablefrom)
+- [Converting a Java String Into a Boolean](https://www.baeldung.com/java-string-to-boolean)
 - [[<-- Prev]](/core-java-modules/core-java-lang-2)

core-java-modules/core-java-lang-3/pom.xml

@@ -39,4 +39,4 @@
         <assertj.version>3.12.2</assertj.version>
     </properties>
       
-</project>
+</project>

core-java-modules/core-java-lang-3/src/main/java/com/baeldung/staticvariables/StaticVariableDemo.java

@@ -0,0 +1,23 @@
+package com.baeldung.staticvariables;
+
+public class StaticVariableDemo {
+    public static int i;
+    public static int j = 20;
+    public static int z;
+
+    static {
+        z = 30;
+        a = 40;
+    }
+
+    public static int a = 50;
+
+    public static final int b = 100;
+
+    public StaticVariableDemo() {
+    }
+
+    static class Nested {
+        public static String nestedClassStaticVariable = "test";
+    }
+}

core-java-modules/core-java-lang-3/src/test/java/com/baeldung/staticvariables/StaticVariableUnitTest.java

@@ -0,0 +1,113 @@
+package com.baeldung.staticvariables;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.lang.reflect.Field;
+
+import org.junit.jupiter.api.Test;
+
+public class StaticVariableUnitTest {
+
+    @Test
+    public void initializeStaticVariable_checkAssignedValues() {
+
+        try {
+            Class<?> staticVariableDemo = this.getClass()
+                .getClassLoader()
+                .loadClass("com.baeldung.staticvariables.StaticVariableDemo");
+
+            Field field1 = staticVariableDemo.getField("i");
+
+            assertThat(field1.getInt(staticVariableDemo)).isEqualTo(0);
+
+            Field field2 = staticVariableDemo.getField("j");
+
+            assertThat(field2.getInt(staticVariableDemo)).isEqualTo(20);
+
+        } catch (ClassNotFoundException | NoSuchFieldException | SecurityException e) {
+            e.printStackTrace();
+        } catch (IllegalArgumentException e) {
+            e.printStackTrace();
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    @Test
+    public void initializeStaticVariable_checkStaticBlock() {
+
+        try {
+            Class<?> staticVariableDemo = this.getClass()
+                .getClassLoader()
+                .loadClass("com.baeldung.staticvariables.StaticVariableDemo");
+
+            Field field1 = staticVariableDemo.getField("z");
+
+            assertThat(field1.getInt(staticVariableDemo)).isEqualTo(30);
+
+            Field field2 = staticVariableDemo.getField("a");
+
+            assertThat(field2.getInt(staticVariableDemo)).isEqualTo(50);
+
+        } catch (ClassNotFoundException | NoSuchFieldException | SecurityException e) {
+            e.printStackTrace();
+        } catch (IllegalArgumentException e) {
+            e.printStackTrace();
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    @Test
+    public void initializeStaticVariable_checkFinalValues() {
+
+        try {
+            Class<?> staticVariableDemo = this.getClass()
+                .getClassLoader()
+                .loadClass("com.baeldung.staticvariables.StaticVariableDemo");
+
+            Field field1 = staticVariableDemo.getField("b");
+
+            assertThat(field1.getInt(staticVariableDemo)).isEqualTo(100);
+
+        } catch (ClassNotFoundException | NoSuchFieldException | SecurityException e) {
+            e.printStackTrace();
+        } catch (IllegalArgumentException e) {
+            e.printStackTrace();
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    @Test
+    public void initializeStaticVariable_checkInnerClassValues() {
+
+        try {
+            Class<?> staticVariableDemo = this.getClass()
+                .getClassLoader()
+                .loadClass("com.baeldung.staticvariables.StaticVariableDemo");
+
+            Class<?>[] nestedClasses = staticVariableDemo.getClasses();
+
+            for (Class<?> nestedClass : nestedClasses) {
+                if (nestedClass.getName()
+                    .equals("Nested")) {
+
+                    Field field1 = nestedClass.getField("nestedClassStaticVariable");
+                    assertThat(field1.get(nestedClass)).isEqualTo("test");
+                }
+            }
+
+        } catch (ClassNotFoundException | NoSuchFieldException | SecurityException e) {
+            e.printStackTrace();
+        } catch (IllegalArgumentException e) {
+            e.printStackTrace();
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        }
+
+    }
+}

core-java-modules/core-java-lang-oop-methods/README.md

@@ -3,7 +3,9 @@
 This module contains articles about methods in Java
 
 ### Relevant Articles: 
+
 - [Methods in Java](https://www.baeldung.com/java-methods)
 - [Method Overloading and Overriding in Java](https://www.baeldung.com/java-method-overload-override)
 - [Java equals() and hashCode() Contracts](https://www.baeldung.com/java-equals-hashcode-contracts)
 - [Guide to hashCode() in Java](https://www.baeldung.com/java-hashcode)
+- [The Covariant Return Type in Java](https://www.baeldung.com/java-covariant-return-type)

core-java-modules/core-java-networking-2/README.md

@@ -12,4 +12,5 @@ This module contains articles about networking in Java
 - [Authentication with HttpUrlConnection](https://www.baeldung.com/java-http-url-connection)
 - [Download a File from an URL in Java](https://www.baeldung.com/java-download-file)
 - [Handling java.net.ConnectException](https://www.baeldung.com/java-net-connectexception)
+- [Getting MAC addresses in Java](https://www.baeldung.com/java-mac-address)
 - [[<-- Prev]](/core-java-modules/core-java-networking)

core-java-modules/core-java-reflection-2/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Reading the Value of ‘private’ Fields from a Different Class in Java](https://www.baeldung.com/java-reflection-read-private-field-value)

core-java-modules/core-java-reflection/README.MD

@@ -8,5 +8,4 @@
 - [Changing Annotation Parameters At Runtime](http://www.baeldung.com/java-reflection-change-annotation-params)
 - [Dynamic Proxies in Java](http://www.baeldung.com/java-dynamic-proxies)
 - [What Causes java.lang.reflect.InvocationTargetException?](https://www.baeldung.com/java-lang-reflect-invocationtargetexception)
-- [How to Find all Getters Returning Null](http://www.baeldung.com/java-getters-returning-null)
 - [How to Get a Name of a Method Being Executed?](http://www.baeldung.com/java-name-of-executing-method)

core-java-modules/core-java-regex/README.md

@@ -3,6 +3,7 @@
 ## Core Java 8 Cookbooks and Examples
 
 ### Relevant Articles: 
+
 - [An Overview of Regular Expressions Performance in Java](https://www.baeldung.com/java-regex-performance)
 - [A Guide To Java Regular Expressions API](http://www.baeldung.com/regular-expressions-java)
 - [Guide to Escaping Characters in Java RegExps](http://www.baeldung.com/java-regexp-escape-char)
@@ -11,3 +12,4 @@
 - [How to Use Regular Expressions to Replace Tokens in Strings](https://www.baeldung.com/java-regex-token-replacement)
 - [Regular Expressions \s and \s+ in Java](https://www.baeldung.com/java-regex-s-splus)
 - [Validate Phone Numbers With Java Regex](https://www.baeldung.com/java-regex-validate-phone-numbers)
+- [How to Count the Number of Matches for a Regex?](https://www.baeldung.com/java-count-regex-matches)

core-java-modules/core-java-security-2/README.md

@@ -9,4 +9,5 @@ This module contains articles about core Java Security
 - [Hashing a Password in Java](https://www.baeldung.com/java-password-hashing)
 - [SHA-256 and SHA3-256 Hashing in Java](https://www.baeldung.com/sha-256-hashing-java)
 - [Checksums in Java](https://www.baeldung.com/java-checksums)
+- [How to Read PEM File to Get Public and Private Keys](https://www.baeldung.com/java-read-pem-file-keys)
 - More articles: [[<-- prev]](/core-java-modules/core-java-security)

core-java-modules/core-java-string-operations-3/README.md

@@ -0,0 +1,3 @@
+### Relevant Articles:
+
+- [Version Comparison in Java](https://www.baeldung.com/java-comparing-versions)

core-java-modules/pom.xml

@@ -72,6 +72,7 @@
 
         <module>core-java-io</module>
         <module>core-java-io-2</module>
+        <module>core-java-io-3</module>
         <module>core-java-io-apis</module>
         <module>core-java-io-conversions</module>
         <module>core-java-io-conversions-2</module>

core-kotlin-modules/core-kotlin-collections/README.md

@@ -3,6 +3,7 @@
 This module contains articles about core Kotlin collections.
 
 ### Relevant articles:
+
 - [Split a List Into Parts in Kotlin](https://www.baeldung.com/kotlin-split-list-into-parts)
 - [Finding an Element in a List Using Kotlin](https://www.baeldung.com/kotlin-finding-element-in-list)
 - [Overview of Kotlin Collections API](https://www.baeldung.com/kotlin-collections-api)
@@ -12,3 +13,4 @@ This module contains articles about core Kotlin collections.
 - [Difference between fold and reduce in Kotlin](https://www.baeldung.com/kotlin/fold-vs-reduce)
 - [Guide to Sorting in Kotlin](https://www.baeldung.com/kotlin-sort)
 - [Working With Lists in Kotlin](https://www.baeldung.com/kotlin/lists)
+- [Iterating Collections by Index in Kotlin](https://www.baeldung.com/kotlin/iterating-collections-by-index)

core-kotlin-modules/core-kotlin-collections/src/main/kotlin/com/baeldung/index/IndexedIteration.kt

@@ -0,0 +1,33 @@
+package com.baeldung.index
+
+fun main() {
+
+    // Index only
+    val colors = listOf("Red", "Green", "Blue")
+    for (i in colors.indices) {
+        println(colors[i])
+    }
+
+    val colorArray = arrayOf("Red", "Green", "Blue")
+    for (i in colorArray.indices) {
+        println(colorArray[i])
+    }
+
+    (0 until colors.size).forEach { println(colors[it]) }
+    for (i in 0 until colors.size) {
+        println(colors[i])
+    }
+
+    // Index and Value
+    colors.forEachIndexed { i, v -> println("The value for index $i is $v") }
+    for (indexedValue in colors.withIndex()) {
+        println("The value for index ${indexedValue.index} is ${indexedValue.value}")
+    }
+
+    for ((i, v) in colors.withIndex()) {
+        println("The value for index $i is $v")
+    }
+
+    colors.filterIndexed { i, _ -> i % 2 == 0 }
+    colors.filterIndexed { _, v -> v == "RED" }
+}

core-kotlin-modules/core-kotlin-lang-oop-2/README.md

@@ -7,4 +7,5 @@ This module contains articles about Object-Oriented Programming in Kotlin
 - [Generics in Kotlin](https://www.baeldung.com/kotlin-generics)
 - [Delegated Properties in Kotlin](https://www.baeldung.com/kotlin-delegated-properties)
 - [Delegation Pattern in Kotlin](https://www.baeldung.com/kotlin-delegation-pattern)
+- [Anonymous Inner Classes in Kotlin](https://www.baeldung.com/kotlin/anonymous-inner-classes)
 - [[<-- Prev]](/core-kotlin-modules/core-kotlin-lang-oop)

core-kotlin-modules/core-kotlin-lang-oop-2/src/main/kotlin/com/baeldung/anonymous/Anonymous.kt

@@ -0,0 +1,41 @@
+package com.baeldung.anonymous
+
+import java.io.Serializable
+import java.nio.channels.Channel
+
+fun main() {
+    val channel = object : Channel {
+        override fun isOpen() = false
+
+        override fun close() {
+        }
+    }
+
+    val maxEntries = 10
+    val lruCache = object : LinkedHashMap<String, Int>(10, 0.75f) {
+
+        override fun removeEldestEntry(eldest: MutableMap.MutableEntry<String, Int>?): Boolean {
+            return size > maxEntries
+        }
+    }
+
+    val map = object : LinkedHashMap<String, Int>() {
+        // omitted
+    }
+
+    val serializableChannel = object : Channel, Serializable {
+        override fun isOpen(): Boolean {
+            TODO("Not yet implemented")
+        }
+
+        override fun close() {
+            TODO("Not yet implemented")
+        }
+    }
+
+    val obj = object {
+        val question = "answer"
+        val answer = 42
+    }
+    println("The ${obj.question} is ${obj.answer}")
+}

data-structures/README.md

@@ -11,3 +11,4 @@ This module contains articles about data structures in Java
 - [Introduction to Big Queue](https://www.baeldung.com/java-big-queue)
 - [Guide to AVL Trees in Java](https://www.baeldung.com/java-avl-trees)
 - [Graphs in Java](https://www.baeldung.com/java-graphs)
+- [Implementing a Ring Buffer in Java](https://www.baeldung.com/java-ring-buffer)

ddd/src/main/java/com/baeldung/ddd/order/config/CustomMongoConfiguration.java

@@ -0,0 +1,46 @@
+package com.baeldung.ddd.order.config;
+
+import org.bson.Document;
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.data.convert.ReadingConverter;
+import org.springframework.data.mongodb.core.convert.MongoCustomConversions;
+
+import java.math.BigDecimal;
+import java.util.Collections;
+
+@Configuration
+public class CustomMongoConfiguration {
+
+    @Bean
+    public MongoCustomConversions customConversions() {
+        return new MongoCustomConversions(Collections.singletonList(DocumentToMoneyConverter.INSTANCE));
+    }
+
+    @ReadingConverter
+    enum DocumentToMoneyConverter implements Converter<Document, Money> {
+
+        INSTANCE;
+
+        @Override
+        public Money convert(Document source) {
+            Document money = source.get("money", Document.class);
+
+            return Money.of(getCurrency(money), getAmount(money));
+        }
+
+        private CurrencyUnit getCurrency(Document money) {
+            Document currency = money.get("currency", Document.class);
+            String currencyCode = currency.getString("code");
+            return CurrencyUnit.of(currencyCode);
+        }
+
+        private BigDecimal getAmount(Document money) {
+            String amount = money.getString("amount");
+            return BigDecimal.valueOf(Double.parseDouble(amount));
+        }
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/jpa/PersistOrderLiveTest.java

@@ -1,19 +1,24 @@
 package com.baeldung.ddd.order.jpa;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
-import java.math.BigDecimal;
-import java.util.Arrays;
-
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
 
+import java.math.BigDecimal;
+import java.util.Arrays;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/*
+ To run this test we need to run the databases first.
+ A dedicated docker-compose.yml file is located under the resources directory.
+ We can run it by simple executing `docker-compose up`.
+ */
 @SpringJUnitConfig
 @SpringBootTest
-public class PersistOrderIntegrationTest {
+public class PersistOrderLiveTest {
     @Autowired
     private JpaOrderRepository repository;
 

ddd/src/test/java/com/baeldung/ddd/order/mongo/OrderMongoLiveTest.java

@@ -17,9 +17,14 @@ import com.baeldung.ddd.order.Order;
 import com.baeldung.ddd.order.OrderLine;
 import com.baeldung.ddd.order.Product;
 
+/*
+ To run this test we need to run the databases first.
+ A dedicated docker-compose.yml file is located under the resources directory.
+ We can run it by simple executing `docker-compose up`.
+ */
 @SpringJUnitConfig
 @SpringBootTest
-public class OrderMongoIntegrationTest {
+public class OrderMongoLiveTest {
     @Autowired
     private OrderMongoRepository repo;
 

ddd/src/test/java/com/baeldung/dddhexagonalspring/infrastracture/repository/CassandraDbOrderRepositoryLiveTest.java

@@ -18,10 +18,15 @@ import com.baeldung.dddhexagonalspring.domain.Product;
 import com.baeldung.dddhexagonalspring.domain.repository.OrderRepository;
 import com.baeldung.dddhexagonalspring.infrastracture.repository.cassandra.SpringDataCassandraOrderRepository;
 
+/*
+ To run this test we need to run the databases first.
+ A dedicated docker-compose.yml file is located under the resources directory.
+ We can run it by simple executing `docker-compose up`.
+ */
 @SpringJUnitConfig
 @SpringBootTest
 @TestPropertySource("classpath:ddd-layers-test.properties")
-class CassandraDbOrderRepositoryIntegrationTest {
+class CassandraDbOrderRepositoryLiveTest {
 
     @Autowired
     private SpringDataCassandraOrderRepository cassandraOrderRepository;

ddd/src/test/java/com/baeldung/dddhexagonalspring/infrastracture/repository/MongoDbOrderRepositoryLiveTest.java

@@ -18,10 +18,15 @@ import com.baeldung.dddhexagonalspring.domain.Product;
 import com.baeldung.dddhexagonalspring.domain.repository.OrderRepository;
 import com.baeldung.dddhexagonalspring.infrastracture.repository.mongo.SpringDataMongoOrderRepository;
 
+/*
+ To run this test we need to run the databases first.
+ A dedicated docker-compose.yml file is located under the resources directory.
+ We can run it by simple executing `docker-compose up`.
+ */
 @SpringJUnitConfig
 @SpringBootTest
 @TestPropertySource("classpath:ddd-layers-test.properties")
-class MongoDbOrderRepositoryIntegrationTest {
+class MongoDbOrderRepositoryLiveTest {
 
     @Autowired
     private SpringDataMongoOrderRepository mongoOrderRepository;

docker/docker-spring-boot/mvnw

@@ -0,0 +1,310 @@
+#!/bin/sh
+# ----------------------------------------------------------------------------
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#    https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+# ----------------------------------------------------------------------------
+
+# ----------------------------------------------------------------------------
+# Maven Start Up Batch script
+#
+# Required ENV vars:
+# ------------------
+#   JAVA_HOME - location of a JDK home dir
+#
+# Optional ENV vars
+# -----------------
+#   M2_HOME - location of maven2's installed home dir
+#   MAVEN_OPTS - parameters passed to the Java VM when running Maven
+#     e.g. to debug Maven itself, use
+#       set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+#   MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+# ----------------------------------------------------------------------------
+
+if [ -z "$MAVEN_SKIP_RC" ] ; then
+
+  if [ -f /etc/mavenrc ] ; then
+    . /etc/mavenrc
+  fi
+
+  if [ -f "$HOME/.mavenrc" ] ; then
+    . "$HOME/.mavenrc"
+  fi
+
+fi
+
+# OS specific support.  $var _must_ be set to either true or false.
+cygwin=false;
+darwin=false;
+mingw=false
+case "`uname`" in
+  CYGWIN*) cygwin=true ;;
+  MINGW*) mingw=true;;
+  Darwin*) darwin=true
+    # Use /usr/libexec/java_home if available, otherwise fall back to /Library/Java/Home
+    # See https://developer.apple.com/library/mac/qa/qa1170/_index.html
+    if [ -z "$JAVA_HOME" ]; then
+      if [ -x "/usr/libexec/java_home" ]; then
+        export JAVA_HOME="`/usr/libexec/java_home`"
+      else
+        export JAVA_HOME="/Library/Java/Home"
+      fi
+    fi
+    ;;
+esac
+
+if [ -z "$JAVA_HOME" ] ; then
+  if [ -r /etc/gentoo-release ] ; then
+    JAVA_HOME=`java-config --jre-home`
+  fi
+fi
+
+if [ -z "$M2_HOME" ] ; then
+  ## resolve links - $0 may be a link to maven's home
+  PRG="$0"
+
+  # need this for relative symlinks
+  while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+      PRG="$link"
+    else
+      PRG="`dirname "$PRG"`/$link"
+    fi
+  done
+
+  saveddir=`pwd`
+
+  M2_HOME=`dirname "$PRG"`/..
+
+  # make it fully qualified
+  M2_HOME=`cd "$M2_HOME" && pwd`
+
+  cd "$saveddir"
+  # echo Using m2 at $M2_HOME
+fi
+
+# For Cygwin, ensure paths are in UNIX format before anything is touched
+if $cygwin ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --unix "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --unix "$CLASSPATH"`
+fi
+
+# For Mingw, ensure paths are in UNIX format before anything is touched
+if $mingw ; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME="`(cd "$M2_HOME"; pwd)`"
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME="`(cd "$JAVA_HOME"; pwd)`"
+fi
+
+if [ -z "$JAVA_HOME" ]; then
+  javaExecutable="`which javac`"
+  if [ -n "$javaExecutable" ] && ! [ "`expr \"$javaExecutable\" : '\([^ ]*\)'`" = "no" ]; then
+    # readlink(1) is not available as standard on Solaris 10.
+    readLink=`which readlink`
+    if [ ! `expr "$readLink" : '\([^ ]*\)'` = "no" ]; then
+      if $darwin ; then
+        javaHome="`dirname \"$javaExecutable\"`"
+        javaExecutable="`cd \"$javaHome\" && pwd -P`/javac"
+      else
+        javaExecutable="`readlink -f \"$javaExecutable\"`"
+      fi
+      javaHome="`dirname \"$javaExecutable\"`"
+      javaHome=`expr "$javaHome" : '\(.*\)/bin'`
+      JAVA_HOME="$javaHome"
+      export JAVA_HOME
+    fi
+  fi
+fi
+
+if [ -z "$JAVACMD" ] ; then
+  if [ -n "$JAVA_HOME"  ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+      # IBM's JDK on AIX uses strange locations for the executables
+      JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+      JAVACMD="$JAVA_HOME/bin/java"
+    fi
+  else
+    JAVACMD="`which java`"
+  fi
+fi
+
+if [ ! -x "$JAVACMD" ] ; then
+  echo "Error: JAVA_HOME is not defined correctly." >&2
+  echo "  We cannot execute $JAVACMD" >&2
+  exit 1
+fi
+
+if [ -z "$JAVA_HOME" ] ; then
+  echo "Warning: JAVA_HOME environment variable is not set."
+fi
+
+CLASSWORLDS_LAUNCHER=org.codehaus.plexus.classworlds.launcher.Launcher
+
+# traverses directory structure from process work directory to filesystem root
+# first directory with .mvn subdirectory is considered project base directory
+find_maven_basedir() {
+
+  if [ -z "$1" ]
+  then
+    echo "Path not specified to find_maven_basedir"
+    return 1
+  fi
+
+  basedir="$1"
+  wdir="$1"
+  while [ "$wdir" != '/' ] ; do
+    if [ -d "$wdir"/.mvn ] ; then
+      basedir=$wdir
+      break
+    fi
+    # workaround for JBEAP-8937 (on Solaris 10/Sparc)
+    if [ -d "${wdir}" ]; then
+      wdir=`cd "$wdir/.."; pwd`
+    fi
+    # end of workaround
+  done
+  echo "${basedir}"
+}
+
+# concatenates all lines of a file
+concat_lines() {
+  if [ -f "$1" ]; then
+    echo "$(tr -s '\n' ' ' < "$1")"
+  fi
+}
+
+BASE_DIR=`find_maven_basedir "$(pwd)"`
+if [ -z "$BASE_DIR" ]; then
+  exit 1;
+fi
+
+##########################################################################################
+# Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+# This allows using the maven wrapper in projects that prohibit checking in binary data.
+##########################################################################################
+if [ -r "$BASE_DIR/.mvn/wrapper/maven-wrapper.jar" ]; then
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Found .mvn/wrapper/maven-wrapper.jar"
+    fi
+else
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Couldn't find .mvn/wrapper/maven-wrapper.jar, downloading it ..."
+    fi
+    if [ -n "$MVNW_REPOURL" ]; then
+      jarUrl="$MVNW_REPOURL/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    else
+      jarUrl="https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    fi
+    while IFS="=" read key value; do
+      case "$key" in (wrapperUrl) jarUrl="$value"; break ;;
+      esac
+    done < "$BASE_DIR/.mvn/wrapper/maven-wrapper.properties"
+    if [ "$MVNW_VERBOSE" = true ]; then
+      echo "Downloading from: $jarUrl"
+    fi
+    wrapperJarPath="$BASE_DIR/.mvn/wrapper/maven-wrapper.jar"
+    if $cygwin; then
+      wrapperJarPath=`cygpath --path --windows "$wrapperJarPath"`
+    fi
+
+    if command -v wget > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found wget ... using wget"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            wget "$jarUrl" -O "$wrapperJarPath"
+        else
+            wget --http-user=$MVNW_USERNAME --http-password=$MVNW_PASSWORD "$jarUrl" -O "$wrapperJarPath"
+        fi
+    elif command -v curl > /dev/null; then
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Found curl ... using curl"
+        fi
+        if [ -z "$MVNW_USERNAME" ] || [ -z "$MVNW_PASSWORD" ]; then
+            curl -o "$wrapperJarPath" "$jarUrl" -f
+        else
+            curl --user $MVNW_USERNAME:$MVNW_PASSWORD -o "$wrapperJarPath" "$jarUrl" -f
+        fi
+
+    else
+        if [ "$MVNW_VERBOSE" = true ]; then
+          echo "Falling back to using Java to download"
+        fi
+        javaClass="$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.java"
+        # For Cygwin, switch paths to Windows format before running javac
+        if $cygwin; then
+          javaClass=`cygpath --path --windows "$javaClass"`
+        fi
+        if [ -e "$javaClass" ]; then
+            if [ ! -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Compiling MavenWrapperDownloader.java ..."
+                fi
+                # Compiling the Java class
+                ("$JAVA_HOME/bin/javac" "$javaClass")
+            fi
+            if [ -e "$BASE_DIR/.mvn/wrapper/MavenWrapperDownloader.class" ]; then
+                # Running the downloader
+                if [ "$MVNW_VERBOSE" = true ]; then
+                  echo " - Running MavenWrapperDownloader.java ..."
+                fi
+                ("$JAVA_HOME/bin/java" -cp .mvn/wrapper MavenWrapperDownloader "$MAVEN_PROJECTBASEDIR")
+            fi
+        fi
+    fi
+fi
+##########################################################################################
+# End of extension
+##########################################################################################
+
+export MAVEN_PROJECTBASEDIR=${MAVEN_BASEDIR:-"$BASE_DIR"}
+if [ "$MVNW_VERBOSE" = true ]; then
+  echo $MAVEN_PROJECTBASEDIR
+fi
+MAVEN_OPTS="$(concat_lines "$MAVEN_PROJECTBASEDIR/.mvn/jvm.config") $MAVEN_OPTS"
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin; then
+  [ -n "$M2_HOME" ] &&
+    M2_HOME=`cygpath --path --windows "$M2_HOME"`
+  [ -n "$JAVA_HOME" ] &&
+    JAVA_HOME=`cygpath --path --windows "$JAVA_HOME"`
+  [ -n "$CLASSPATH" ] &&
+    CLASSPATH=`cygpath --path --windows "$CLASSPATH"`
+  [ -n "$MAVEN_PROJECTBASEDIR" ] &&
+    MAVEN_PROJECTBASEDIR=`cygpath --path --windows "$MAVEN_PROJECTBASEDIR"`
+fi
+
+# Provide a "standardized" way to retrieve the CLI args that will
+# work with both Windows and non-Windows executions.
+MAVEN_CMD_LINE_ARGS="$MAVEN_CONFIG $@"
+export MAVEN_CMD_LINE_ARGS
+
+WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+exec "$JAVACMD" \
+  $MAVEN_OPTS \
+  -classpath "$MAVEN_PROJECTBASEDIR/.mvn/wrapper/maven-wrapper.jar" \
+  "-Dmaven.home=${M2_HOME}" "-Dmaven.multiModuleProjectDirectory=${MAVEN_PROJECTBASEDIR}" \
+  ${WRAPPER_LAUNCHER} $MAVEN_CONFIG "$@"

docker/docker-spring-boot/mvnw.cmd

@@ -0,0 +1,182 @@
+@REM ----------------------------------------------------------------------------
+@REM Licensed to the Apache Software Foundation (ASF) under one
+@REM or more contributor license agreements.  See the NOTICE file
+@REM distributed with this work for additional information
+@REM regarding copyright ownership.  The ASF licenses this file
+@REM to you under the Apache License, Version 2.0 (the
+@REM "License"); you may not use this file except in compliance
+@REM with the License.  You may obtain a copy of the License at
+@REM
+@REM    https://www.apache.org/licenses/LICENSE-2.0
+@REM
+@REM Unless required by applicable law or agreed to in writing,
+@REM software distributed under the License is distributed on an
+@REM "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+@REM KIND, either express or implied.  See the License for the
+@REM specific language governing permissions and limitations
+@REM under the License.
+@REM ----------------------------------------------------------------------------
+
+@REM ----------------------------------------------------------------------------
+@REM Maven Start Up Batch script
+@REM
+@REM Required ENV vars:
+@REM JAVA_HOME - location of a JDK home dir
+@REM
+@REM Optional ENV vars
+@REM M2_HOME - location of maven2's installed home dir
+@REM MAVEN_BATCH_ECHO - set to 'on' to enable the echoing of the batch commands
+@REM MAVEN_BATCH_PAUSE - set to 'on' to wait for a keystroke before ending
+@REM MAVEN_OPTS - parameters passed to the Java VM when running Maven
+@REM     e.g. to debug Maven itself, use
+@REM set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000
+@REM MAVEN_SKIP_RC - flag to disable loading of mavenrc files
+@REM ----------------------------------------------------------------------------
+
+@REM Begin all REM lines with '@' in case MAVEN_BATCH_ECHO is 'on'
+@echo off
+@REM set title of command window
+title %0
+@REM enable echoing by setting MAVEN_BATCH_ECHO to 'on'
+@if "%MAVEN_BATCH_ECHO%" == "on"  echo %MAVEN_BATCH_ECHO%
+
+@REM set %HOME% to equivalent of $HOME
+if "%HOME%" == "" (set "HOME=%HOMEDRIVE%%HOMEPATH%")
+
+@REM Execute a user defined script before this one
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPre
+@REM check for pre script, once with legacy .bat ending and once with .cmd ending
+if exist "%HOME%\mavenrc_pre.bat" call "%HOME%\mavenrc_pre.bat"
+if exist "%HOME%\mavenrc_pre.cmd" call "%HOME%\mavenrc_pre.cmd"
+:skipRcPre
+
+@setlocal
+
+set ERROR_CODE=0
+
+@REM To isolate internal variables from possible post scripts, we use another setlocal
+@setlocal
+
+@REM ==== START VALIDATION ====
+if not "%JAVA_HOME%" == "" goto OkJHome
+
+echo.
+echo Error: JAVA_HOME not found in your environment. >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+:OkJHome
+if exist "%JAVA_HOME%\bin\java.exe" goto init
+
+echo.
+echo Error: JAVA_HOME is set to an invalid directory. >&2
+echo JAVA_HOME = "%JAVA_HOME%" >&2
+echo Please set the JAVA_HOME variable in your environment to match the >&2
+echo location of your Java installation. >&2
+echo.
+goto error
+
+@REM ==== END VALIDATION ====
+
+:init
+
+@REM Find the project base dir, i.e. the directory that contains the folder ".mvn".
+@REM Fallback to current working directory if not found.
+
+set MAVEN_PROJECTBASEDIR=%MAVEN_BASEDIR%
+IF NOT "%MAVEN_PROJECTBASEDIR%"=="" goto endDetectBaseDir
+
+set EXEC_DIR=%CD%
+set WDIR=%EXEC_DIR%
+:findBaseDir
+IF EXIST "%WDIR%"\.mvn goto baseDirFound
+cd ..
+IF "%WDIR%"=="%CD%" goto baseDirNotFound
+set WDIR=%CD%
+goto findBaseDir
+
+:baseDirFound
+set MAVEN_PROJECTBASEDIR=%WDIR%
+cd "%EXEC_DIR%"
+goto endDetectBaseDir
+
+:baseDirNotFound
+set MAVEN_PROJECTBASEDIR=%EXEC_DIR%
+cd "%EXEC_DIR%"
+
+:endDetectBaseDir
+
+IF NOT EXIST "%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config" goto endReadAdditionalConfig
+
+@setlocal EnableExtensions EnableDelayedExpansion
+for /F "usebackq delims=" %%a in ("%MAVEN_PROJECTBASEDIR%\.mvn\jvm.config") do set JVM_CONFIG_MAVEN_PROPS=!JVM_CONFIG_MAVEN_PROPS! %%a
+@endlocal & set JVM_CONFIG_MAVEN_PROPS=%JVM_CONFIG_MAVEN_PROPS%
+
+:endReadAdditionalConfig
+
+SET MAVEN_JAVA_EXE="%JAVA_HOME%\bin\java.exe"
+set WRAPPER_JAR="%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.jar"
+set WRAPPER_LAUNCHER=org.apache.maven.wrapper.MavenWrapperMain
+
+set DOWNLOAD_URL="https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+
+FOR /F "tokens=1,2 delims==" %%A IN ("%MAVEN_PROJECTBASEDIR%\.mvn\wrapper\maven-wrapper.properties") DO (
+    IF "%%A"=="wrapperUrl" SET DOWNLOAD_URL=%%B
+)
+
+@REM Extension to allow automatically downloading the maven-wrapper.jar from Maven-central
+@REM This allows using the maven wrapper in projects that prohibit checking in binary data.
+if exist %WRAPPER_JAR% (
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Found %WRAPPER_JAR%
+    )
+) else (
+    if not "%MVNW_REPOURL%" == "" (
+        SET DOWNLOAD_URL="%MVNW_REPOURL%/io/takari/maven-wrapper/0.5.6/maven-wrapper-0.5.6.jar"
+    )
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Couldn't find %WRAPPER_JAR%, downloading it ...
+        echo Downloading from: %DOWNLOAD_URL%
+    )
+
+    powershell -Command "&{"^
+		"$webclient = new-object System.Net.WebClient;"^
+		"if (-not ([string]::IsNullOrEmpty('%MVNW_USERNAME%') -and [string]::IsNullOrEmpty('%MVNW_PASSWORD%'))) {"^
+		"$webclient.Credentials = new-object System.Net.NetworkCredential('%MVNW_USERNAME%', '%MVNW_PASSWORD%');"^
+		"}"^
+		"[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12; $webclient.DownloadFile('%DOWNLOAD_URL%', '%WRAPPER_JAR%')"^
+		"}"
+    if "%MVNW_VERBOSE%" == "true" (
+        echo Finished downloading %WRAPPER_JAR%
+    )
+)
+@REM End of extension
+
+@REM Provide a "standardized" way to retrieve the CLI args that will
+@REM work with both Windows and non-Windows executions.
+set MAVEN_CMD_LINE_ARGS=%*
+
+%MAVEN_JAVA_EXE% %JVM_CONFIG_MAVEN_PROPS% %MAVEN_OPTS% %MAVEN_DEBUG_OPTS% -classpath %WRAPPER_JAR% "-Dmaven.multiModuleProjectDirectory=%MAVEN_PROJECTBASEDIR%" %WRAPPER_LAUNCHER% %MAVEN_CONFIG% %*
+if ERRORLEVEL 1 goto error
+goto end
+
+:error
+set ERROR_CODE=1
+
+:end
+@endlocal & set ERROR_CODE=%ERROR_CODE%
+
+if not "%MAVEN_SKIP_RC%" == "" goto skipRcPost
+@REM check for post script, once with legacy .bat ending and once with .cmd ending
+if exist "%HOME%\mavenrc_post.bat" call "%HOME%\mavenrc_post.bat"
+if exist "%HOME%\mavenrc_post.cmd" call "%HOME%\mavenrc_post.cmd"
+:skipRcPost
+
+@REM pause the script if MAVEN_BATCH_PAUSE is set to 'on'
+if "%MAVEN_BATCH_PAUSE%" == "on" pause
+
+if "%MAVEN_TERMINATE_CMD%" == "on" exit %ERROR_CODE%
+
+exit /B %ERROR_CODE%

docker/docker-spring-boot/pom.xml

@@ -0,0 +1,54 @@
+<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-starter-parent</artifactId>
+        <version>2.3.1.RELEASE</version>
+        <relativePath/> <!-- lookup parent from repository -->
+    </parent>
+    <groupId>com.baeldung.docker</groupId>
+    <artifactId>spring-boot-docker</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+    <name>spring-boot-docker</name>
+    <description>Demo project showing Spring Boot and Docker</description>
+
+    <properties>
+        <java.version>8</java.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+            <exclusions>
+                <exclusion>
+                    <groupId>org.junit.vintage</groupId>
+                    <artifactId>junit-vintage-engine</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+                <configuration>
+                    <layers>
+                        <enabled>true</enabled>
+                    </layers>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

docker/docker-spring-boot/src/main/docker/Dockerfile

@@ -0,0 +1,15 @@
+# To build, run the following command from the top level project directory:
+#
+# docker build -f src/main/docker/Dockerfile .
+
+FROM adoptopenjdk:11-jre-hotspot as builder
+ARG JAR_FILE=target/*.jar
+COPY ${JAR_FILE} application.jar
+RUN java -Djarmode=layertools -jar application.jar extract
+
+FROM adoptopenjdk:11-jre-hotspot
+COPY --from=builder dependencies/ ./
+COPY --from=builder snapshot-dependencies/ ./
+COPY --from=builder spring-boot-loader/ ./
+COPY --from=builder application/ ./
+ENTRYPOINT ["java", "org.springframework.boot.loader.JarLauncher"]

docker/docker-spring-boot/src/main/java/com/baeldung/docker/DemoApplication.java

@@ -0,0 +1,13 @@
+package com.baeldung.docker;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class DemoApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(DemoApplication.class, args);
+    }
+
+}

docker/docker-spring-boot/src/main/java/com/baeldung/docker/HelloController.java

@@ -0,0 +1,16 @@
+package com.baeldung.docker;
+
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+public class HelloController {
+
+    @GetMapping("/hello")
+    public ResponseEntity<String> hello()
+    {
+        return ResponseEntity.ok("hello2    ");
+    }
+
+}

docker/docker-spring-boot/src/main/resources/application.properties

@@ -0,0 +1 @@
+

gradle-5/README.md

@@ -1,3 +1,4 @@
 ### Relevant Articles:
 
 - [Run a Java main Method Using Gradle](https://www.baeldung.com/gradle-run-java-main)
+- [Finding Unused Gradle Dependencies](https://www.baeldung.com/gradle-finding-unused-dependencies)

guava-2/README.md

@@ -1,7 +0,0 @@
-## Guava
-
-This module contains articles a Google Guava
-
-### Relevant Articles: 
-- [Introduction to Guava Throwables](https://www.baeldung.com/guava-throwables)
-- [Guava CharMatcher](https://www.baeldung.com/guava-string-charmatcher)

guava-modules/guava-18/README.md

@@ -1,8 +1,5 @@
-=========
-
-## Guava and Hamcrest Cookbooks and Examples
+## Guava 18
 
 
 ### Relevant Articles: 
-- [Guava Functional Cookbook](http://www.baeldung.com/guava-functions-predicates)
 - [Guava 18: What’s New?](http://www.baeldung.com/whats-new-in-guava-18)

guava-modules/guava-19/README.md

@@ -1,5 +1,3 @@
-=========
-
 ## Guava 19
 
 

guava-modules/guava-21/README.md

@@ -1,4 +1,6 @@
+## Guava 21
+
 ### Relevant articles:
+
 - [New Stream, Comparator and Collector in Guava 21](http://www.baeldung.com/guava-21-new)
 - [New in Guava 21 common.util.concurrent](http://www.baeldung.com/guava-21-util-concurrent)
-- [Zipping Collections in Java](http://www.baeldung.com/java-collections-zip)

guava-modules/guava-21/pom.xml

@@ -13,17 +13,8 @@
         <relativePath>../</relativePath>
     </parent>
 
-    <dependencies>
-        <dependency>
-            <groupId>org.jooq</groupId>
-            <artifactId>jool</artifactId>
-            <version>${jool.version}</version>
-        </dependency>
-    </dependencies>
-
     <properties>
         <guava.version>21.0</guava.version>
-        <jool.version>0.9.12</jool.version>
     </properties>
 
 </project>

guava-modules/guava-collections-list/README.md

@@ -0,0 +1,8 @@
+## Guava Collections List examples
+
+This module contains articles about list collections in Guava
+
+### Relevant Articles: 
+
+- [Partition a List in Java](https://www.baeldung.com/java-list-split)
+- [Guava – Lists](https://www.baeldung.com/guava-lists)

guava-modules/guava-collections-list/pom.xml

@@ -4,15 +4,15 @@
     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>guava-collections</artifactId>
+    <artifactId>guava-collections-list</artifactId>
     <version>0.1.0-SNAPSHOT</version>
-    <name>guava-collections</name>
+    <name>guava-collections-list</name>
 
     <parent>
         <groupId>com.baeldung</groupId>
-        <artifactId>parent-java</artifactId>
+        <artifactId>guava-modules</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../parent-java</relativePath>
+        <relativePath>../</relativePath>
     </parent>
 
     <dependencies>

guava-modules/guava-collections-map/pom.xml

@@ -9,9 +9,9 @@
 
     <parent>
         <groupId>com.baeldung</groupId>
-        <artifactId>parent-java</artifactId>
+        <artifactId>guava-modules</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../parent-java</relativePath>
+        <relativePath>../</relativePath>
     </parent>
 
     <dependencies>

guava-modules/guava-collections-set/pom.xml

@@ -8,9 +8,9 @@
 
     <parent>
         <groupId>com.baeldung</groupId>
-        <artifactId>parent-java</artifactId>
+        <artifactId>guava-modules</artifactId>
         <version>0.0.1-SNAPSHOT</version>
-        <relativePath>../parent-java</relativePath>
+        <relativePath>../</relativePath>
     </parent>
 
     <dependencies>

guava-modules/guava-collections/README.md

@@ -8,9 +8,8 @@ This module contains articles about Google Guava collections
 - [Guava Ordering Cookbook](https://www.baeldung.com/guava-order)
 - [Guide to Guava’s Ordering](https://www.baeldung.com/guava-ordering)
 - [Hamcrest Collections Cookbook](https://www.baeldung.com/hamcrest-collections-arrays)
-- [Partition a List in Java](https://www.baeldung.com/java-list-split)
 - [Filtering and Transforming Collections in Guava](https://www.baeldung.com/guava-filter-and-transform-a-collection)
 - [Guava – Join and Split Collections](https://www.baeldung.com/guava-joiner-and-splitter-tutorial)
-- [Guava – Lists](https://www.baeldung.com/guava-lists)
 - [Guide to Guava MinMaxPriorityQueue and EvictingQueue](https://www.baeldung.com/guava-minmax-priority-queue-and-evicting-queue)
 - [Guide to Guava Table](https://www.baeldung.com/guava-table)
+- [Zipping Collections in Java](http://www.baeldung.com/java-collections-zip)

guava-modules/guava-collections/pom.xml

@@ -0,0 +1,95 @@
+<?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>guava-collections</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>guava-collections</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>guava-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../</relativePath>
+    </parent>
+
+    <dependencies>
+        <!-- utils -->
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-collections4</artifactId>
+            <version>${commons-collections4.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${commons-lang3.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.jooq</groupId>
+            <artifactId>jool</artifactId>
+            <version>${jool.version}</version>
+        </dependency>
+
+        <!-- test scoped -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>${junit-jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.vintage</groupId>
+            <artifactId>junit-vintage-engine</artifactId>
+            <version>${junit-jupiter.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+
+        <!-- https://mvnrepository.com/artifact/org.hamcrest/java-hamcrest -->
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>java-hamcrest</artifactId>
+            <version>${java-hamcrest.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>guava-collections</finalName>
+
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>2.22.2</version>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <!-- util -->
+        <commons-collections4.version>4.1</commons-collections4.version>
+        <jool.version>0.9.12</jool.version>
+
+        <!-- testing -->
+        <assertj.version>3.6.1</assertj.version>
+        <java-hamcrest.version>2.0.0.0</java-hamcrest.version>
+        <junit-jupiter.version>5.6.2</junit-jupiter.version>
+    </properties>
+
+</project>