Merge remote-tracking branch 'baeldung/master' into BAEL-4015

aws-lambda/shipping-tracker/ShippingFunction/src/main/java/com/baeldung/lambda/shipping/App.java

@@ -6,10 +6,12 @@ import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyRequestEvent;
 import com.amazonaws.services.lambda.runtime.events.APIGatewayProxyResponseEvent;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.zaxxer.hikari.HikariDataSource;
 import org.hibernate.SessionFactory;
 import org.hibernate.boot.MetadataSources;
 import org.hibernate.boot.registry.StandardServiceRegistry;
 import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
+import org.hibernate.engine.jdbc.connections.spi.ConnectionProvider;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -22,11 +24,14 @@ import static org.hibernate.cfg.AvailableSettings.PASS;
  */
 public class App implements RequestHandler<APIGatewayProxyRequestEvent, APIGatewayProxyResponseEvent> {
 private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
+    private SessionFactory sessionFactory = createSessionFactory();
 
     public APIGatewayProxyResponseEvent handleRequest(APIGatewayProxyRequestEvent input, Context context) {
-        try (SessionFactory sessionFactory = createSessionFactory()) {
+        try {
             ShippingService service = new ShippingService(sessionFactory, new ShippingDao());
             return routeRequest(input, service);
+        } finally {
+            flushConnectionPool();
         }
     }
 
@@ -105,4 +110,12 @@ private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();
           .buildMetadata()
           .buildSessionFactory();
     }
+
+    private void flushConnectionPool() {
+        ConnectionProvider connectionProvider = sessionFactory.getSessionFactoryOptions()
+          .getServiceRegistry()
+          .getService(ConnectionProvider.class);
+        HikariDataSource hikariDataSource = connectionProvider.unwrap(HikariDataSource.class);
+        hikariDataSource.getHikariPoolMXBean().softEvictConnections();
+    }
 }

core-java-modules/core-java-14/src/test/java/com/baeldung/java14/character/IsLetterOrAlphabetUnitTest.java

@@ -0,0 +1,30 @@
+package com.baeldung.java14.character;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertFalse;
+
+public class IsLetterOrAlphabetUnitTest {
+
+    @Test
+    public void givenACharacter_whenLetter_thenAssertIsLetterTrue() {
+        assertTrue(Character.isLetter(65));
+    }
+
+    @Test
+    public void givenACharacter_whenLetter_thenAssertIsAlphabeticTrue() {
+        assertTrue(Character.isAlphabetic(65));
+    }
+
+    @Test
+    public void givenACharacter_whenAlphabeticAndNotLetter_thenAssertIsLetterFalse() {
+        assertFalse(Character.isLetter(837));
+    }
+
+    @Test
+    public void givenACharacter_whenAlphabeticAndNotLetter_thenAssertIsAlphabeticTrue() {
+        assertTrue(Character.isAlphabetic(837));
+    }
+
+}

core-java-modules/core-java-15/README.md

@@ -4,4 +4,4 @@ This module contains articles about Java 15.
 
 ### Relevant articles
 
-- TODO: add article links here
+- [Sealed Classes and Interfaces in Java 15](https://www.baeldung.com/java-sealed-classes-interfaces)

core-java-modules/core-java-15/pom.xml

@@ -51,8 +51,8 @@
                 <configuration>
                     <release>${maven.compiler.release}</release>
                     <compilerArgs>--enable-preview</compilerArgs>
-                    <source>15</source>
+                    <source>14</source>
-                    <target>15</target>
+                    <target>14</target>
                 </configuration>
             </plugin>
             <plugin>

core-java-modules/core-java-15/src/main/java/com/baeldung/whatsnew/records/Person.java

@@ -0,0 +1,15 @@
+package com.baeldung.whatsnew.records;
+
+/**
+ * Java record with a header indicating 2 fields.
+ */
+public record Person(String name, int age) {
+    /**
+     * Public constructor that does some basic validation.
+     */
+    public Person {
+        if (age < 0) {
+            throw new IllegalArgumentException("Age cannot be negative");
+        }
+    }
+}

core-java-modules/core-java-15/src/main/java/com/baeldung/whatsnew/sealedclasses/Employee.java

@@ -0,0 +1,9 @@
+package com.baeldung.whatsnew.sealedclasses;
+
+import java.util.Date;
+
+public non-sealed class Employee extends Person {
+    public Date getHiredDate() {
+        return new Date();
+    }
+}

core-java-modules/core-java-15/src/main/java/com/baeldung/whatsnew/sealedclasses/Manager.java

@@ -0,0 +1,4 @@
+package com.baeldung.whatsnew.sealedclasses;
+
+public final class Manager extends Person {
+}

core-java-modules/core-java-15/src/main/java/com/baeldung/whatsnew/sealedclasses/Person.java

@@ -0,0 +1,21 @@
+package com.baeldung.whatsnew.sealedclasses;
+
+import java.util.Date;
+
+public sealed class Person permits Employee, Manager {
+    /**
+     * Demonstration of pattern matching for instanceof
+     *
+     * @param person A Person object
+     * @return
+     */
+    public static void patternMatchingDemo(Person person) {
+        if(person instanceof Employee employee) {
+            Date hiredDate = employee.getHiredDate();
+        }
+
+        if(person instanceof Employee employee && employee.getHiredDate() != null) {
+            Date hiredDate = employee.getHiredDate();
+        }
+    }
+}

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

@@ -7,3 +7,4 @@ This module contains complete guides about arrays in Java
 - [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)
 - [Guide to ArrayStoreException](https://www.baeldung.com/java-arraystoreexception)
+- [Creating a Generic Array in Java](https://www.baeldung.com/java-generic-array)

core-java-modules/core-java-arrays-guides/src/main/java/com/baeldung/genericarrays/MyStack.java

@@ -0,0 +1,30 @@
+package com.baeldung.genericarrays;
+
+import java.lang.reflect.Array;
+
+public class MyStack<E> {
+    private E[] elements;
+    private int size = 0;
+
+    public MyStack(Class<E> clazz, int capacity) {
+        elements = (E[]) Array.newInstance(clazz, capacity);
+    }
+
+    public void push(E item) {
+        if (size == elements.length) {
+            throw new RuntimeException();
+        }
+        elements[size++] = item;
+    }
+
+    public E pop() {
+        if (size == 0) {
+            throw new RuntimeException();
+        }
+        return elements[--size];
+    }
+
+    public E[] getAllElements() {
+        return elements;
+    }
+}

core-java-modules/core-java-arrays-guides/src/test/java/com/baeldung/genericarrays/ListToArrayUnitTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.genericarrays;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+
+public class ListToArrayUnitTest {
+
+    @Test
+    public void givenListOfItems_whenToArray_thenReturnArrayOfItems() {
+        List<String> items = new LinkedList<>();
+        items.add("first item");
+        items.add("second item");
+
+        String[] itemsAsArray = items.toArray(new String[0]);
+
+        assertEquals("first item", itemsAsArray[0]);
+        assertEquals("second item", itemsAsArray[1]);
+    }
+}

core-java-modules/core-java-arrays-guides/src/test/java/com/baeldung/genericarrays/MyStackUnitTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.genericarrays;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class MyStackUnitTest {
+
+    @Test
+    public void givenStackWithTwoItems_whenPop_thenReturnLastAdded() {
+        MyStack<String> myStack = new MyStack<>(String.class, 2);
+        myStack.push("hello");
+        myStack.push("example");
+
+        assertEquals("example", myStack.pop());
+    }
+
+    @Test (expected = RuntimeException.class)
+    public void givenStackWithFixedCapacity_whenExceedCapacity_thenThrowException() {
+        MyStack<Integer> myStack = new MyStack<>(Integer.class, 2);
+        myStack.push(100);
+        myStack.push(200);
+        myStack.push(300);
+    }
+
+    @Test(expected = RuntimeException.class)
+    public void givenStack_whenPopOnEmptyStack_thenThrowException() {
+        MyStack<Integer> myStack = new MyStack<>(Integer.class, 1);
+        myStack.push(100);
+        myStack.pop();
+        myStack.pop();
+    }
+
+    @Test
+    public void givenStackWithItems_whenGetAllElements_thenSizeShouldEqualTotal() {
+        MyStack<String> myStack = new MyStack<>(String.class, 2);
+        myStack.push("hello");
+        myStack.push("example");
+
+        String[] items = myStack.getAllElements();
+
+        assertEquals(2, items.length);
+    }
+}

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

@@ -0,0 +1,6 @@
+## Core Java Character
+
+This module contains articles about Java Character Class
+
+### Relevant Articles: 
+- Character#isAlphabetic vs Character#isLetter

core-java-modules/core-java-char/pom.xml

@@ -0,0 +1,42 @@
+<?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-char</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-char</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>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${openjdk.jmh.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>${openjdk.jmh.version}</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <openjdk.jmh.version>1.19</openjdk.jmh.version>
+        <assertj.version>3.11.1</assertj.version>
+    </properties>
+
+</project>

core-java-modules/core-java-char/src/test/java/com/baeldung/character/CharacterGeneralCategoryTypeUnitTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.character;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertTrue;
+
+public class CharacterGeneralCategoryTypeUnitTest {
+    @Test
+    public void givenACharacter_whenUpperCaseLetter_thenAssertTrue() {
+        assertTrue(Character.getType('U') == Character.UPPERCASE_LETTER);
+    }
+
+    @Test
+    public void givenACharacter_whenLowerCaseLetter_thenAssertTrue() {
+        assertTrue(Character.getType('u') == Character.LOWERCASE_LETTER);
+    }
+
+    @Test
+    public void givenACharacter_whenTitleCaseLetter_thenAssertTrue() {
+        assertTrue(Character.getType('\u01f2') == Character.TITLECASE_LETTER);
+    }
+
+    @Test
+    public void givenACharacter_whenModifierLetter_thenAssertTrue() {
+        assertTrue(Character.getType('\u02b0') == Character.MODIFIER_LETTER);
+    }
+
+    @Test
+    public void givenACharacter_whenOtherLetter_thenAssertTrue() {
+        assertTrue(Character.getType('\u05d0') == Character.OTHER_LETTER);
+    }
+
+    @Test
+    public void givenACharacter_whenLetterNumber_thenAssertTrue() {
+        assertTrue(Character.getType('\u2164') == Character.LETTER_NUMBER);
+    }
+}

core-java-modules/core-java-char/src/test/java/com/baeldung/character/IsLetterOrAlphabetUnitTest.java

@@ -0,0 +1,28 @@
+package com.baeldung.character;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertFalse;
+
+public class IsLetterOrAlphabetUnitTest {
+    @Test
+    public void givenACharacter_whenLetter_thenAssertIsLetterTrue() {
+        assertTrue(Character.isLetter('a'));
+    }
+
+    @Test
+    public void givenACharacter_whenLetter_thenAssertIsAlphabeticTrue() {
+        assertTrue(Character.isAlphabetic('a'));
+    }
+
+    @Test
+    public void givenACharacter_whenAlphabeticAndNotLetter_thenAssertIsLetterFalse() {
+        assertFalse(Character.isLetter('\u2164'));
+    }
+
+    @Test
+    public void givenACharacter_whenAlphabeticAndNotLetter_thenAssertIsAlphabeticTrue() {
+        assertTrue(Character.isAlphabetic('\u2164'));
+    }
+}

core-java-modules/core-java-collections-array-list/README.md

@@ -8,4 +8,4 @@ This module contains articles about the Java ArrayList collection
 - [ClassCastException: Arrays$ArrayList cannot be cast to ArrayList](https://www.baeldung.com/java-classcastexception-arrays-arraylist)
 - [Multi Dimensional ArrayList in Java](https://www.baeldung.com/java-multi-dimensional-arraylist)
 - [Removing an Element From an ArrayList](https://www.baeldung.com/java-arraylist-remove-element)
-
+- [The Capacity of an ArrayList vs the Size of an Array in Java](https://www.baeldung.com/java-list-capacity-array-size)

core-java-modules/core-java-collections-array-list/src/test/java/com/baeldung/listcapacityvsarraysize/ArrayCreatorUnitTest.java

@@ -0,0 +1,20 @@
+package com.baeldung.listcapacityvsarraysize;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+class ArrayCreatorUnitTest {
+
+    @Test
+    void whenSizeOfAnArrayIsNonZero_thenReturnNewArrayOfGivenSize() {
+        Integer[] array = new Integer[10];
+        assertEquals(10, array.length);
+    }
+
+    @Test
+    void whenSizeOfAnArrayIsLessThanZero_thenThrowException() {
+        assertThrows(NegativeArraySizeException.class, () -> { Integer[] array = new Integer[-1]; });
+    }
+}

core-java-modules/core-java-collections-array-list/src/test/java/com/baeldung/listcapacityvsarraysize/ArrayListCreatorUnitTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.listcapacityvsarraysize;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.ArrayList;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ArrayListCreatorUnitTest {
+
+    @Test
+    void givenValidCapacityOfList_whenCreateListInvoked_thenCreateNewArrayListWithGivenCapacity() {
+        ArrayList<Integer> list = new ArrayList<>(100);
+
+        assertNotNull(list);
+    }
+
+    @Test
+    void givenInvalidCapacityOfList_whenCreateListInvoked_thenThrowException() {
+        assertThrows(IllegalArgumentException.class, () -> new ArrayList<>(-1));
+    }
+
+    @Test
+    void givenValidCapacityOfList_whenCreateListInvoked_thenCreateNewArrayListWithSizeZero() {
+        assertEquals(0, new ArrayList<Integer>(100).size());
+    }
+}

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

@@ -6,3 +6,4 @@
 - [AbstractMethodError in Java](https://www.baeldung.com/java-abstractmethoderror)
 - [Java IndexOutOfBoundsException “Source Does Not Fit in Dest”](https://www.baeldung.com/java-indexoutofboundsexception)
 - [Localizing Exception Messages in Java](https://www.baeldung.com/java-localize-exception-messages)
+- [Explanation of ClassCastException in Java](https://www.baeldung.com/java-classcastexception)

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Amphibian.java

@@ -1,9 +1,9 @@
 package com.baeldung.exceptions.classcastexception;
 
-public class Reptile implements Animal {
+public class Amphibian implements Animal {
 
     @Override
     public String getName() {
-        return "Reptile";
+        return "Amphibian";
     }
 }

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/classcastexception/Frog.java

@@ -1,6 +1,6 @@
 package com.baeldung.exceptions.classcastexception;
 
-public class Frog extends Reptile {
+public class Frog extends Amphibian {
 
     @Override
     public String getName() {

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/nosuchfielderror/Dependency.java

@@ -0,0 +1,8 @@
+package com.baeldung.exceptions.nosuchfielderror;
+
+public class Dependency {
+    
+    // This needed to be commented post compilation of NoSuchFielDError and Compile
+    public static String message = "Hello Baeldung!!";
+    
+}

core-java-modules/core-java-exceptions-3/src/main/java/com/baeldung/exceptions/nosuchfielderror/FieldErrorExample.java

@@ -0,0 +1,20 @@
+package com.baeldung.exceptions.nosuchfielderror;
+
+public class FieldErrorExample {
+
+    public static void main(String... args) {
+
+        fetchAndPrint();
+    }
+
+    public static String getDependentMessage() {
+
+        return Dependency.message;
+    }
+
+    public static void fetchAndPrint() {
+
+        System.out.println(getDependentMessage());
+    }
+
+}

core-java-modules/core-java-exceptions-3/src/test/java/com/baeldung/exceptions/nosuchfielderror/FieldErrorExampleUnitTest.java

@@ -0,0 +1,16 @@
+package com.baeldung.exceptions.nosuchfielderror;
+
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+public class FieldErrorExampleUnitTest {
+    
+    @Test
+    public void whenDependentMessage_returnMessage() {
+        
+        String dependentMessage = FieldErrorExample.getDependentMessage();
+        assertTrue("Hello Baeldung!!".equals(dependentMessage));
+    }
+    
+}

core-java-modules/core-java-io/src/main/java/com/baeldung/unzip/UnzipFile.java

@@ -16,31 +16,42 @@ public class UnzipFile {
         ZipEntry zipEntry = zis.getNextEntry();
         while (zipEntry != null) {
             final File newFile = newFile(destDir, zipEntry);
-            final FileOutputStream fos = new FileOutputStream(newFile);
+            if (zipEntry.isDirectory()) {
-            int len;
+                if (!newFile.isDirectory() && !newFile.mkdirs()) {
-            while ((len = zis.read(buffer)) > 0) {
+                    throw new IOException("Failed to create directory " + newFile);
-                fos.write(buffer, 0, len);
+                }
+            } else {
+                File parent = newFile.getParentFile();
+                if (!parent.isDirectory() && !parent.mkdirs()) {
+                    throw new IOException("Failed to create directory " + parent);
+                }
+
+                final FileOutputStream fos = new FileOutputStream(newFile);
+                int len;
+                while ((len = zis.read(buffer)) > 0) {
+                    fos.write(buffer, 0, len);
+                }
+                fos.close();
             }
-            fos.close();
             zipEntry = zis.getNextEntry();
         }
         zis.closeEntry();
         zis.close();
     }
-    
+
     /**
      * @see https://snyk.io/research/zip-slip-vulnerability
      */
     public static File newFile(File destinationDir, ZipEntry zipEntry) throws IOException {
         File destFile = new File(destinationDir, zipEntry.getName());
-        
+
         String destDirPath = destinationDir.getCanonicalPath();
         String destFilePath = destFile.getCanonicalPath();
-        
+
         if (!destFilePath.startsWith(destDirPath + File.separator)) {
             throw new IOException("Entry is outside of the target dir: " + zipEntry.getName());
         }
-        
+
         return destFile;
     }
 }

core-java-modules/core-java-lang-3/src/main/java/com/baeldung/iterationcounter/IterationCounter.java

@@ -0,0 +1,68 @@
+package com.baeldung.iterationcounter;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.BiConsumer;
+import java.util.function.Consumer;
+import java.util.stream.Stream;
+
+public class IterationCounter {
+    public static final List<String> IMDB_TOP_MOVIES = Arrays.asList("The Shawshank Redemption",
+      "The Godfather", "The Godfather II", "The Dark Knight");
+
+    public static List<String> getRankingsWithForLoop(List<String> movies) {
+        List<String> rankings = new ArrayList<>();
+        for (int i = 0; i < movies.size(); i++) {
+            String ranking = (i + 1) + ": " + movies.get(i);
+            rankings.add(ranking);
+        }
+        return rankings;
+    }
+
+    public static List<String> getRankingsWithForEachLoop(List<String> movies) {
+        List<String> rankings = new ArrayList<>();
+        int i = 0;
+        for (String movie : movies) {
+            String ranking = (i + 1) + ": " + movies.get(i);
+            rankings.add(ranking);
+
+            i++;
+        }
+        return rankings;
+    }
+
+    public static List<String> getRankingsWithFunctionalForEachLoop(List<String> movies) {
+        List<String> rankings = new ArrayList<>();
+        forEachWithCounter(movies, (i, movie) -> {
+            String ranking = (i + 1) + ": " + movie;
+            rankings.add(ranking);
+        });
+
+        return rankings;
+    }
+
+    public static <T> void forEachWithCounter(Iterable<T> source, BiConsumer<Integer, T> consumer) {
+        int i = 0;
+        for (T item : source) {
+            consumer.accept(i, item);
+            i++;
+        }
+    }
+
+    public static List<String> getRankingsWithStream(Stream<String> movies) {
+        List<String> rankings = new ArrayList<>();
+        movies.forEach(withCounter((i, movie) -> {
+            String ranking = (i + 1) + ": " + movie;
+            rankings.add(ranking);
+        }));
+
+        return rankings;
+    }
+
+    public static <T> Consumer<T> withCounter(BiConsumer<Integer, T> consumer) {
+        AtomicInteger counter = new AtomicInteger(0);
+        return item -> consumer.accept(counter.getAndIncrement(), item);
+    }
+}

core-java-modules/core-java-lang-3/src/test/java/com/baeldung/iterationcounter/IterationCounterUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.iterationcounter;
+
+import org.junit.Test;
+
+import static com.baeldung.iterationcounter.IterationCounter.*;
+import static org.assertj.core.api.Assertions.*;
+
+public class IterationCounterUnitTest {
+    @Test
+    public void givenRankings_whenCalculateWithForLoop_thenRankingsCorrect() {
+        assertThat(getRankingsWithForLoop(IMDB_TOP_MOVIES))
+          .containsExactly("1: The Shawshank Redemption",
+            "2: The Godfather", "3: The Godfather II", "4: The Dark Knight");
+    }
+
+    @Test
+    public void givenRankings_whenCalculateWithForEachLoop_thenRankingsCorrect() {
+        assertThat(getRankingsWithForEachLoop(IMDB_TOP_MOVIES))
+          .containsExactly("1: The Shawshank Redemption",
+            "2: The Godfather", "3: The Godfather II", "4: The Dark Knight");
+    }
+
+    @Test
+    public void givenRankings_whenCalculateWithFunctionalForEach_thenRankingsCorrect() {
+        assertThat(getRankingsWithFunctionalForEachLoop(IMDB_TOP_MOVIES))
+          .containsExactly("1: The Shawshank Redemption",
+            "2: The Godfather", "3: The Godfather II", "4: The Dark Knight");
+    }
+
+    @Test
+    public void givenRankings_whenCalculateWithStream_thenRankingsCorrect() {
+        assertThat(getRankingsWithStream(IMDB_TOP_MOVIES.stream()))
+          .containsExactly("1: The Shawshank Redemption",
+            "2: The Godfather", "3: The Godfather II", "4: The Dark Knight");
+    }
+}

core-java-modules/core-java-lang-oop-types/pom.xml

@@ -12,12 +12,20 @@
     <artifactId>core-java-lang-oop-types</artifactId>
     <name>core-java-lang-oop-types</name>
     <packaging>jar</packaging>
-    
+
     <dependencies>
         <dependency>
             <groupId>org.apache.commons</groupId>
             <artifactId>commons-lang3</artifactId>
             <version>${commons-lang3.version}</version>
         </dependency>
+        <dependency>
+            <groupId>commons-codec</groupId>
+            <artifactId>commons-codec</artifactId>
+            <version>${commons-codec.version}</version>
+        </dependency>
     </dependencies>
+    <properties>
+        <commons-codec.version>1.15</commons-codec.version>
+    </properties>
 </project>

core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/Application.java

@@ -0,0 +1,35 @@
+package com.baeldung.enums.extendenum;
+
+import org.apache.commons.lang3.StringUtils;
+
+import java.util.Arrays;
+import java.util.EnumMap;
+import java.util.Map;
+
+public class Application {
+    private static final Map<ImmutableOperation, Operator> OPERATION_MAP;
+
+    static {
+        OPERATION_MAP = new EnumMap<>(ImmutableOperation.class);
+        OPERATION_MAP.put(ImmutableOperation.TO_LOWER, String::toLowerCase);
+        OPERATION_MAP.put(ImmutableOperation.INVERT_CASE, StringUtils::swapCase);
+        OPERATION_MAP.put(ImmutableOperation.REMOVE_WHITESPACES, input -> input.replaceAll("\\s", ""));
+
+        if (Arrays.stream(ImmutableOperation.values()).anyMatch(it -> !OPERATION_MAP.containsKey(it))) {
+            throw new IllegalStateException("Unmapped enum constant found!");
+        }
+    }
+
+    public String applyImmutableOperation(ImmutableOperation operation, String input) {
+        return OPERATION_MAP.get(operation).apply(input);
+    }
+
+    public String getDescription(StringOperation stringOperation) {
+        return stringOperation.getDescription();
+    }
+
+    public String applyOperation(StringOperation operation, String input) {
+        return operation.apply(input);
+    }
+
+}

core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/ApplicationWithEx.java

@@ -0,0 +1,26 @@
+package com.baeldung.enums.extendenum;
+
+import org.apache.commons.lang3.StringUtils;
+
+import java.util.Arrays;
+import java.util.EnumMap;
+import java.util.Map;
+
+public class ApplicationWithEx {
+    private static final Map<ImmutableOperation, Operator> OPERATION_MAP;
+
+    static {
+        OPERATION_MAP = new EnumMap<>(ImmutableOperation.class);
+        OPERATION_MAP.put(ImmutableOperation.TO_LOWER, String::toLowerCase);
+        OPERATION_MAP.put(ImmutableOperation.INVERT_CASE, StringUtils::swapCase);
+        // ImmutableOperation.REMOVE_WHITESPACES is not mapped
+
+        if (Arrays.stream(ImmutableOperation.values()).anyMatch(it -> !OPERATION_MAP.containsKey(it))) {
+            throw new IllegalStateException("Unmapped enum constant found!");
+        }
+    }
+
+    public String applyImmutableOperation(ImmutableOperation operation, String input) {
+        return OPERATION_MAP.get(operation).apply(input);
+    }
+}

core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/BasicStringOperation.java

@@ -0,0 +1,33 @@
+package com.baeldung.enums.extendenum;
+
+public enum BasicStringOperation implements StringOperation {
+    TRIM("Removing leading and trailing spaces.") {
+        @Override
+        public String apply(String input) {
+            return input.trim();
+        }
+    },
+    TO_UPPER("Changing all characters into upper case.") {
+        @Override
+        public String apply(String input) {
+            return input.toUpperCase();
+        }
+    },
+    REVERSE("Reversing the given string.") {
+        @Override
+        public String apply(String input) {
+            return new StringBuilder(input).reverse().toString();
+        }
+    };
+
+    private String description;
+
+    public String getDescription() {
+        return description;
+    }
+
+    BasicStringOperation(String description) {
+        this.description = description;
+    }
+}
+

core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/ExtendedStringOperation.java

@@ -0,0 +1,31 @@
+package com.baeldung.enums.extendenum;
+
+import org.apache.commons.codec.binary.Base64;
+import org.apache.commons.codec.digest.DigestUtils;
+
+public enum ExtendedStringOperation implements StringOperation {
+    MD5_ENCODE("Encoding the given string using the MD5 algorithm.") {
+        @Override
+        public String apply(String input) {
+            return DigestUtils.md5Hex(input);
+        }
+    },
+    BASE64_ENCODE("Encoding the given string using the BASE64 algorithm.") {
+        @Override
+        public String apply(String input) {
+            return new String(new Base64().encode(input.getBytes()));
+        }
+    };
+
+    private String description;
+
+    ExtendedStringOperation(String description) {
+        this.description = description;
+    }
+
+
+    @Override
+    public String getDescription() {
+        return description;
+    }
+}

core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/ImmutableOperation.java

@@ -0,0 +1,6 @@
+package com.baeldung.enums.extendenum;
+
+public enum ImmutableOperation {
+    REMOVE_WHITESPACES, TO_LOWER, INVERT_CASE
+}
+

core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/Operator.java

@@ -0,0 +1,5 @@
+package com.baeldung.enums.extendenum;
+
+public interface Operator {
+    String apply(String input);
+}

core-java-modules/core-java-lang-oop-types/src/main/java/com/baeldung/enums/extendenum/StringOperation.java

@@ -0,0 +1,7 @@
+package com.baeldung.enums.extendenum;
+
+public interface StringOperation {
+    String getDescription();
+
+    String apply(String input);
+}

core-java-modules/core-java-lang-oop-types/src/test/java/com/baeldung/enums/extendenum/ExtendEnumUnitTest.java

@@ -0,0 +1,43 @@
+package com.baeldung.enums.extendenum;
+
+import org.junit.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class ExtendEnumUnitTest {
+    private Application app = new Application();
+
+    @Test
+    public void givenAStringAndOperation_whenApplyOperation_thenGetExpectedResult() {
+        String input = " hello";
+        String expectedToUpper = " HELLO";
+        String expectedReverse = "olleh ";
+        String expectedTrim = "hello";
+        String expectedBase64 = "IGhlbGxv";
+        String expectedMd5 = "292a5af68d31c10e31ad449bd8f51263";
+        assertEquals(expectedTrim, app.applyOperation(BasicStringOperation.TRIM, input));
+        assertEquals(expectedToUpper, app.applyOperation(BasicStringOperation.TO_UPPER, input));
+        assertEquals(expectedReverse, app.applyOperation(BasicStringOperation.REVERSE, input));
+        assertEquals(expectedBase64, app.applyOperation(ExtendedStringOperation.BASE64_ENCODE, input));
+        assertEquals(expectedMd5, app.applyOperation(ExtendedStringOperation.MD5_ENCODE, input));
+    }
+
+    @Test
+    public void givenAStringAndImmutableOperation_whenApplyOperation_thenGetExpectedResult() {
+        String input = " He ll O ";
+        String expectedToLower = " he ll o ";
+        String expectedRmWhitespace = "HellO";
+        String expectedInvertCase = " hE LL o ";
+        assertEquals(expectedToLower, app.applyImmutableOperation(ImmutableOperation.TO_LOWER, input));
+        assertEquals(expectedRmWhitespace, app.applyImmutableOperation(ImmutableOperation.REMOVE_WHITESPACES, input));
+        assertEquals(expectedInvertCase, app.applyImmutableOperation(ImmutableOperation.INVERT_CASE, input));
+    }
+
+    @Test
+    public void givenUnmappedImmutableOperationValue_whenAppStarts_thenGetException() {
+        Throwable throwable = assertThrows(ExceptionInInitializerError.class, () -> {
+            ApplicationWithEx appEx = new ApplicationWithEx();
+        });
+        assertTrue(throwable.getCause() instanceof IllegalStateException);
+    }
+}

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

@@ -0,0 +1,8 @@
+## Core Java Networking (Part 3)
+
+This module contains articles about networking in Java
+
+### Relevant Articles
+
+- TODO: add link once live
+- [[<-- Prev]](/core-java-modules/core-java-networking-2)

core-java-modules/core-java-networking-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-networking-3</artifactId>
+    <name>core-java-networking-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>../pom.xml</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-core</artifactId>
+            <version>${spring.core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.eclipse.jetty</groupId>
+            <artifactId>jetty-server</artifactId>
+            <version>${jetty.embeded.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.tomcat.embed</groupId>
+            <artifactId>tomcat-embed-core</artifactId>
+            <version>${tomcat.embeded.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-networking-3</finalName>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <spring.core.version>5.2.8.RELEASE</spring.core.version>
+        <jetty.embeded.version>9.4.31.v20200723</jetty.embeded.version>
+        <tomcat.embeded.version>10.0.0-M7</tomcat.embeded.version>
+        <assertj.version>3.11.1</assertj.version>
+    </properties>
+
+</project>

core-java-modules/core-java-networking-3/src/test/java/com/baeldung/socket/FindFreePortUnitTest.java

@@ -0,0 +1,150 @@
+package com.baeldung.socket;
+
+import org.apache.catalina.LifecycleException;
+import org.apache.catalina.startup.Tomcat;
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.ServerConnector;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.springframework.util.SocketUtils;
+
+import java.io.IOException;
+import java.net.ServerSocket;
+
+import static org.assertj.core.api.Assertions.*;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class FindFreePortUnitTest {
+
+    private static int FREE_PORT_NUMBER;
+    private static int[] FREE_PORT_RANGE;
+
+    @BeforeAll
+    public static void getExplicitFreePortNumberAndRange() {
+        try (ServerSocket serverSocket = new ServerSocket(0)) {
+            FREE_PORT_NUMBER = serverSocket.getLocalPort();
+            FREE_PORT_RANGE = new int[] {FREE_PORT_NUMBER, FREE_PORT_NUMBER + 1, FREE_PORT_NUMBER + 2};
+        } catch (IOException e) {
+            fail("No free port is available");
+        }
+    }
+
+    @Test
+    public void givenExplicitFreePort_whenCreatingServerSocket_thenThatPortIsAssigned() {
+        try (ServerSocket serverSocket = new ServerSocket(FREE_PORT_NUMBER)) {
+            assertThat(serverSocket).isNotNull();
+            assertThat(serverSocket.getLocalPort()).isEqualTo(FREE_PORT_NUMBER);
+        } catch (IOException e) {
+            fail("Port is not available");
+        }
+    }
+
+    @Test
+    public void givenExplicitOccupiedPort_whenCreatingServerSocket_thenExceptionIsThrown() {
+        try (ServerSocket serverSocket = new ServerSocket(FREE_PORT_NUMBER)) {
+            new ServerSocket(FREE_PORT_NUMBER);
+            fail("Same port cannot be used twice");
+        } catch (IOException e) {
+            assertThat(e).hasMessageContaining("Address already in use");
+        }
+    }
+
+    @Test
+    public void givenExplicitPortRange_whenCreatingServerSocket_thenOnePortIsAssigned() {
+        for (int port : FREE_PORT_RANGE) {
+            try (ServerSocket serverSocket = new ServerSocket(port)) {
+                assertThat(serverSocket).isNotNull();
+                assertThat(serverSocket.getLocalPort()).isEqualTo(port);
+                return;
+            } catch (IOException e) {
+                assertThat(e).hasMessageContaining("Address already in use");
+            }
+        }
+        fail("No free port in the range found");
+    }
+
+    @Test
+    public void givenPortZero_whenCreatingServerSocket_thenFreePortIsAssigned() {
+        try (ServerSocket serverSocket = new ServerSocket(0)) {
+            assertThat(serverSocket).isNotNull();
+            assertThat(serverSocket.getLocalPort()).isGreaterThan(0);
+        } catch (IOException e) {
+            fail("Port is not available");
+        }
+    }
+
+    @Test
+    public void givenAvailableTcpPort_whenCreatingServerSocket_thenThatPortIsAssigned() {
+        int port = SocketUtils.findAvailableTcpPort();
+        try (ServerSocket serverSocket = new ServerSocket(port)) {
+            assertThat(serverSocket).isNotNull();
+            assertThat(serverSocket.getLocalPort()).isEqualTo(port);
+        } catch (IOException e) {
+            fail("Port is not available");
+        }
+    }
+
+    @Test
+    public void givenNoPortDefined_whenCreatingJettyServer_thenFreePortIsAssigned() throws Exception {
+        Server jettyServer = new Server();
+        ServerConnector serverConnector = new ServerConnector(jettyServer);
+        jettyServer.addConnector(serverConnector);
+        try {
+            jettyServer.start();
+            assertThat(serverConnector.getLocalPort()).isGreaterThan(0);
+        } catch (Exception e) {
+            fail("Failed to start Jetty server");
+        } finally {
+            jettyServer.stop();
+            jettyServer.destroy();
+        }
+    }
+
+    @Test
+    public void givenExplicitFreePort_whenCreatingJettyServer_thenThatPortIsAssigned() throws Exception {
+        Server jettyServer = new Server();
+        ServerConnector serverConnector = new ServerConnector(jettyServer);
+        serverConnector.setPort(FREE_PORT_NUMBER);
+        jettyServer.addConnector(serverConnector);
+        try {
+            jettyServer.start();
+            assertThat(serverConnector.getLocalPort()).isEqualTo(FREE_PORT_NUMBER);
+        } catch (Exception e) {
+            fail("Failed to start Jetty server");
+        } finally {
+            jettyServer.stop();
+            jettyServer.destroy();
+        }
+    }
+
+    @Test
+    public void givenPortZero_whenCreatingTomcatServer_thenFreePortIsAssigned() throws Exception {
+        Tomcat tomcatServer = new Tomcat();
+        tomcatServer.setPort(0);
+        try {
+            tomcatServer.start();
+            assertThat(tomcatServer.getConnector().getLocalPort()).isGreaterThan(0);
+        } catch (LifecycleException e) {
+            fail("Failed to start Tomcat server");
+        } finally {
+            tomcatServer.stop();
+            tomcatServer.destroy();
+        }
+    }
+
+    @Test
+    public void givenExplicitFreePort_whenCreatingTomcatServer_thenThatPortIsAssigned() throws Exception {
+        Tomcat tomcatServer = new Tomcat();
+        tomcatServer.setPort(FREE_PORT_NUMBER);
+        try {
+            tomcatServer.start();
+            assertThat(tomcatServer.getConnector().getLocalPort()).isEqualTo(FREE_PORT_NUMBER);
+        } catch (LifecycleException e) {
+            fail("Failed to start Tomcat server");
+        } finally {
+            tomcatServer.stop();
+            tomcatServer.destroy();
+        }
+    }
+
+}

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

@@ -8,5 +8,5 @@ This module contains articles about string APIs.
 - [Guide to java.util.Formatter](https://www.baeldung.com/java-string-formatter)
 - [Guide to StreamTokenizer](https://www.baeldung.com/java-streamtokenizer)
 - [CharSequence vs. String in Java](https://www.baeldung.com/java-char-sequence-string)
-- [StringBuilder and StringBuffer in Java](https://www.baeldung.com/java-string-builder-string-buffer)
+- [StringBuilder vs StringBuffer in Java](https://www.baeldung.com/java-string-builder-string-buffer)
 - [Generate a Secure Random Password in Java](https://www.baeldung.com/java-generate-secure-password)

core-java-modules/pom.xml

@@ -29,7 +29,8 @@
         <module>core-java-arrays-convert</module>
         <module>core-java-arrays-operations-basic</module>
         <module>core-java-arrays-operations-advanced</module>
-        
+
+        <module>core-java-char</module>
         <module>core-java-collections</module>
         <module>core-java-collections-2</module>
         <module>core-java-collections-3</module>

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

@@ -1,11 +0,0 @@
-## Core Kotlin Advanced
-
-This module contains articles about advanced topics in Kotlin.
-
-### Relevant articles:
-- [Building DSLs in Kotlin](https://www.baeldung.com/kotlin-dsl)
-- [Regular Expressions in Kotlin](https://www.baeldung.com/kotlin-regular-expressions)
-- [Idiomatic Logging in Kotlin](https://www.baeldung.com/kotlin-logging)
-- [Mapping of Data Objects in Kotlin](https://www.baeldung.com/kotlin-data-objects)
-- [Reflection with Kotlin](https://www.baeldung.com/kotlin-reflection)
-- [Kotlin Contracts](https://www.baeldung.com/kotlin-contracts)

core-kotlin-modules/core-kotlin-advanced/pom.xml

@@ -1,41 +0,0 @@
-<?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-advanced</artifactId>
-    <name>core-kotlin-advanced</name>
-    <packaging>jar</packaging>
-
-    <parent>
-        <groupId>com.baeldung.core-kotlin-modules</groupId>
-        <artifactId>core-kotlin-modules</artifactId>
-        <version>1.0.0-SNAPSHOT</version>
-    </parent>
-
-    <dependencies>
-        <dependency>
-            <groupId>org.jetbrains.kotlin</groupId>
-            <artifactId>kotlin-stdlib-jdk8</artifactId>
-            <version>${kotlin.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.assertj</groupId>
-            <artifactId>assertj-core</artifactId>
-            <version>${assertj.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.jetbrains.kotlin</groupId>
-            <artifactId>kotlin-test</artifactId>
-            <version>${kotlin.version}</version>
-            <scope>test</scope>
-        </dependency>
-    </dependencies>
-
-    <properties>
-        <kotlin.version>1.3.30</kotlin.version>
-        <assertj.version>3.10.0</assertj.version>
-    </properties>
-
-</project>

core-kotlin-modules/core-kotlin-advanced/src/main/kotlin/com/baeldung/contract/CallsInPlaceEffect.kt

@@ -1,23 +0,0 @@
-package com.baeldung.contract
-
-import kotlin.contracts.ExperimentalContracts
-import kotlin.contracts.InvocationKind
-import kotlin.contracts.contract
-
-@ExperimentalContracts
-inline fun <R> myRun(block: () -> R): R {
-    contract {
-        callsInPlace(block, InvocationKind.EXACTLY_ONCE)
-    }
-    return block()
-}
-
-@ExperimentalContracts
-fun callsInPlace() {
-    val i: Int
-    myRun {
-        i = 1 // Without contract initialization is forbidden due to possible re-assignment
-    }
-    println(i) // Without contract variable might be uninitialized
-}
-

core-kotlin-modules/core-kotlin-advanced/src/main/kotlin/com/baeldung/contract/ReturnsEffect.kt

@@ -1,43 +0,0 @@
-package com.baeldung.contract
-
-import kotlin.contracts.ExperimentalContracts
-import kotlin.contracts.contract
-
-data class Request(val arg: String)
-
-class Service {
-
-    @ExperimentalContracts
-    fun process(request: Request?) {
-        validate(request)
-        println(request.arg)
-    }
-
-}
-
-@ExperimentalContracts
-private fun validate(request: Request?) {
-    contract {
-        returns() implies (request != null)
-    }
-    if (request == null) {
-        throw IllegalArgumentException("Undefined request")
-    }
-}
-
-data class MyEvent(val message: String)
-
-@ExperimentalContracts
-fun processEvent(event: Any?) {
-    if (isInterested(event)) {
-        println(event.message) // Compiler makes smart cast here with the help of contract
-    }
-}
-
-@ExperimentalContracts
-fun isInterested(event: Any?): Boolean {
-    contract {
-        returns(true) implies (event is MyEvent)
-    }
-    return event is MyEvent
-}

core-kotlin-modules/core-kotlin-advanced/src/main/kotlin/com/baeldung/datamapping/User.kt

@@ -1,10 +0,0 @@
-package com.baeldung.datamapping
-
-data class User(
-  val firstName: String,
-  val lastName: String,
-  val street: String,
-  val houseNumber: String,
-  val phone: String,
-  val age: Int,
-  val password: String)

core-kotlin-modules/core-kotlin-advanced/src/main/kotlin/com/baeldung/datamapping/UserExtensions.kt

@@ -1,22 +0,0 @@
-package com.baeldung.datamapping
-
-import kotlin.reflect.full.memberProperties
-
-fun User.toUserView() = UserView(
-        name = "$firstName $lastName",
-        address = "$street $houseNumber",
-        telephone = phone,
-        age = age
-)
-
-fun User.toUserViewReflection() = with(::UserView) {
-    val propertiesByName = User::class.memberProperties.associateBy { it.name }
-    callBy(parameters.associate { parameter ->
-        parameter to when (parameter.name) {
-            UserView::name.name -> "$firstName $lastName"
-            UserView::address.name -> "$street $houseNumber"
-            UserView::telephone.name -> phone
-            else -> propertiesByName[parameter.name]?.get(this@toUserViewReflection)
-        }
-    })
-}

core-kotlin-modules/core-kotlin-advanced/src/main/kotlin/com/baeldung/datamapping/UserView.kt

@@ -1,8 +0,0 @@
-package com.baeldung.datamapping
-
-data class UserView(
-  val name: String,
-  val address: String,
-  val telephone: String,
-  val age: Int
-)

core-kotlin-modules/core-kotlin-advanced/src/main/kotlin/com/baeldung/dsl/SqlDsl.kt

@@ -1,114 +0,0 @@
-package com.baeldung.dsl
-
-abstract class Condition {
-
-    fun and(initializer: Condition.() -> Unit) {
-        addCondition(And().apply(initializer))
-    }
-
-    fun or(initializer: Condition.() -> Unit) {
-        addCondition(Or().apply(initializer))
-    }
-
-    infix fun String.eq(value: Any?) {
-        addCondition(Eq(this, value))
-    }
-
-    protected abstract fun addCondition(condition: Condition)
-}
-
-open class CompositeCondition(private val sqlOperator: String) : Condition() {
-    private val conditions = mutableListOf<Condition>()
-
-    override fun addCondition(condition: Condition) {
-        conditions += condition
-    }
-
-    override fun toString(): String {
-        return if (conditions.size == 1) {
-            conditions.first().toString()
-        } else {
-            conditions.joinToString(prefix = "(", postfix = ")", separator = " $sqlOperator ") {
-                "$it"
-            }
-        }
-    }
-}
-
-class And : CompositeCondition("and")
-
-class Or : CompositeCondition("or")
-
-class Eq(private val column: String, private val value: Any?) : Condition() {
-
-    init {
-        if (value != null && value !is Number && value !is String) {
-            throw IllegalArgumentException("Only <null>, numbers and strings values can be used in the 'where' clause")
-        }
-    }
-
-    override fun addCondition(condition: Condition) {
-        throw IllegalStateException("Can't add a nested condition to the sql 'eq'")
-    }
-
-    override fun toString(): String {
-        return when (value) {
-            null -> "$column is null"
-            is String -> "$column = '$value'"
-            else -> "$column = $value"
-        }
-    }
-}
-
-class SqlSelectBuilder {
-
-    private val columns = mutableListOf<String>()
-    private lateinit var table: String
-    private var condition: Condition? = null
-
-    fun select(vararg columns: String) {
-        if (columns.isEmpty()) {
-            throw IllegalArgumentException("At least one column should be defined")
-        }
-        if (this.columns.isNotEmpty()) {
-            throw IllegalStateException("Detected an attempt to re-define columns to fetch. Current columns list: "
-                                        + "${this.columns}, new columns list: $columns")
-        }
-        this.columns.addAll(columns)
-    }
-
-    fun from(table: String) {
-        this.table = table
-    }
-
-    fun where(initializer: Condition.() -> Unit) {
-        condition = And().apply(initializer)
-    }
-
-    fun build(): String {
-        if (!::table.isInitialized) {
-            throw IllegalStateException("Failed to build an sql select - target table is undefined")
-        }
-        return toString()
-    }
-
-    override fun toString(): String {
-        val columnsToFetch =
-                if (columns.isEmpty()) {
-                    "*"
-                } else {
-                    columns.joinToString(", ")
-                }
-        val conditionString =
-                if (condition == null) {
-                    ""
-                } else {
-                    " where $condition"
-                }
-        return "select $columnsToFetch from $table$conditionString"
-    }
-}
-
-fun query(initializer: SqlSelectBuilder.() -> Unit): SqlSelectBuilder {
-    return SqlSelectBuilder().apply(initializer)
-}

core-kotlin-modules/core-kotlin-advanced/src/main/kotlin/com/baeldung/logging/LoggerAsExtensionOnAny.kt

@@ -1,30 +0,0 @@
-package com.baeldung.logging
-
-import org.slf4j.Logger
-
-open class LoggerAsExtensionOnAny {
-    val logger = logger()
-
-    fun log(s: String) {
-        logger().info(s)
-        logger.info(s)
-    }
-}
-
-class ExtensionSubclass : LoggerAsExtensionOnAny()
-
-fun <T : Any> T.logger(): Logger = getLogger(getClassForLogging(javaClass))
-
-fun main(args: Array<String>) {
-    LoggerAsExtensionOnAny().log("test")
-    ExtensionSubclass().log("sub")
-    "foo".logger().info("foo")
-    1.logger().info("uh-oh!")
-    SomeOtherClass().logger()
-}
-
-class SomeOtherClass {
-    fun logger(): String {
-        return "foo"
-    }
-}

core-kotlin-modules/core-kotlin-advanced/src/main/kotlin/com/baeldung/logging/LoggerAsExtensionOnMarkerInterface.kt

@@ -1,30 +0,0 @@
-package com.baeldung.logging
-
-import org.slf4j.Logger
-import org.slf4j.LoggerFactory
-
-interface Logging
-
-inline fun <reified T : Logging> T.logger(): Logger =
-        //Wrong logger name!
-        //LoggerFactory.getLogger(javaClass.name + " w/interface")
-        LoggerFactory.getLogger(getClassForLogging(T::class.java).name + " w/interface")
-
-open class LoggerAsExtensionOnMarkerInterface : Logging {
-    companion object : Logging {
-        val logger = logger()
-    }
-
-    fun log(s: String) {
-        logger().info(s)
-        logger.info(s)
-    }
-}
-
-class MarkerExtensionSubclass : LoggerAsExtensionOnMarkerInterface()
-
-fun main(args: Array<String>) {
-    LoggerAsExtensionOnMarkerInterface().log("test")
-    MarkerExtensionSubclass().log("sub")
-    "foo".logger().info("foo")
-}

core-kotlin-modules/core-kotlin-advanced/src/main/kotlin/com/baeldung/logging/LoggerAsProperty.kt

@@ -1,17 +0,0 @@
-package com.baeldung.logging
-
-open class LoggerAsProperty {
-    private val logger = getLogger(javaClass)
-
-    fun log(s: String) {
-        logger.info(s)
-    }
-
-}
-
-class PropertySubclass : LoggerAsProperty()
-
-fun main(args: Array<String>) {
-    LoggerAsProperty().log("test")
-    PropertySubclass().log("sub")
-}

core-kotlin-modules/core-kotlin-advanced/src/main/kotlin/com/baeldung/logging/LoggerAsPropertyDelegate.kt

@@ -1,47 +0,0 @@
-package com.baeldung.logging
-
-import org.slf4j.Logger
-import kotlin.properties.ReadOnlyProperty
-import kotlin.reflect.KProperty
-
-open class LoggerAsPropertyDelegate {
-    private val lazyLogger by lazyLogger()
-    protected val logger by LoggerDelegate()
-    private val logger2 = logger
-
-    companion object {
-        private val lazyLoggerComp by lazyLogger()
-        private val loggerComp by LoggerDelegate()
-    }
-
-    open fun log(s: String) {
-        logger.info(s)
-        logger2.info(s)
-        lazyLogger.info(s)
-        loggerComp.info(s)
-        lazyLoggerComp.info(s)
-    }
-
-}
-
-class DelegateSubclass : LoggerAsPropertyDelegate() {
-    override fun log(s: String) {
-        logger.info("-- in sub")
-        super.log(s)
-    }
-}
-
-fun lazyLogger(forClass: Class<*>): Lazy<Logger> =
-        lazy { getLogger(getClassForLogging(forClass)) }
-
-fun <T : Any> T.lazyLogger(): Lazy<Logger> = lazyLogger(javaClass)
-
-fun main(args: Array<String>) {
-    LoggerAsPropertyDelegate().log("test")
-    DelegateSubclass().log("sub")
-}
-
-class LoggerDelegate<in R : Any> : ReadOnlyProperty<R, Logger> {
-    override fun getValue(thisRef: R, property: KProperty<*>) =
-            getLogger(getClassForLogging(thisRef.javaClass))
-}

core-kotlin-modules/core-kotlin-advanced/src/main/kotlin/com/baeldung/logging/LoggerInCompanionObject.kt

@@ -1,44 +0,0 @@
-package com.baeldung.logging
-
-open class LoggerInCompanionObject {
-    companion object {
-        private val loggerWithExplicitClass = getLogger(LoggerInCompanionObject::class.java)
-        @Suppress("JAVA_CLASS_ON_COMPANION")
-        private val loggerWithWrongClass = getLogger(javaClass)
-        @Suppress("JAVA_CLASS_ON_COMPANION")
-        private val logger = getLogger(javaClass.enclosingClass)
-    }
-
-    fun log(s: String) {
-        loggerWithExplicitClass.info(s)
-        loggerWithWrongClass.info(s)
-        logger.info(s)
-    }
-
-    class Inner {
-        companion object {
-            private val loggerWithExplicitClass = getLogger(Inner::class.java)
-            @Suppress("JAVA_CLASS_ON_COMPANION")
-            @JvmStatic
-            private val loggerWithWrongClass = getLogger(javaClass)
-            @Suppress("JAVA_CLASS_ON_COMPANION")
-            @JvmStatic
-            private val logger = getLogger(javaClass.enclosingClass)
-        }
-
-        fun log(s: String) {
-            loggerWithExplicitClass.info(s)
-            loggerWithWrongClass.info(s)
-            logger.info(s)
-        }
-    }
-
-}
-
-class CompanionSubclass : LoggerInCompanionObject()
-
-fun main(args: Array<String>) {
-    LoggerInCompanionObject().log("test")
-    LoggerInCompanionObject.Inner().log("test")
-    CompanionSubclass().log("sub")
-}

core-kotlin-modules/core-kotlin-advanced/src/main/kotlin/com/baeldung/logging/Util.kt

@@ -1,13 +0,0 @@
-package com.baeldung.logging
-
-import org.slf4j.Logger
-import org.slf4j.LoggerFactory
-import kotlin.reflect.full.companionObject
-
-fun getLogger(forClass: Class<*>): Logger = LoggerFactory.getLogger(forClass)
-
-fun <T : Any> getClassForLogging(javaClass: Class<T>): Class<*> {
-    return javaClass.enclosingClass?.takeIf {
-        it.kotlin.companionObject?.java == javaClass
-    } ?: javaClass
-}

core-kotlin-modules/core-kotlin-advanced/src/test/kotlin/com/baeldung/datamapping/UserTest.kt

@@ -1,43 +0,0 @@
-package com.baeldung.datamapping
-
-import org.junit.jupiter.api.Test
-import org.junit.jupiter.api.assertAll
-import kotlin.test.assertEquals
-
-class UserTest {
-
-    @Test
-    fun `maps User to UserResponse using extension function`() {
-        val p = buildUser()
-        val view = p.toUserView()
-        assertUserView(view)
-    }
-
-    @Test
-    fun `maps User to UserResponse using reflection`() {
-        val p = buildUser()
-        val view = p.toUserViewReflection()
-        assertUserView(view)
-    }
-
-    private fun buildUser(): User {
-        return User(
-          "Java",
-          "Duke",
-          "Javastreet",
-          "42",
-          "1234567",
-          30,
-          "s3cr37"
-        )
-    }
-
-    private fun assertUserView(pr: UserView) {
-        assertAll(
-          { assertEquals("Java Duke", pr.name) },
-          { assertEquals("Javastreet 42", pr.address) },
-          { assertEquals("1234567", pr.telephone) },
-          { assertEquals(30, pr.age) }
-        )
-    }
-}

core-kotlin-modules/core-kotlin-advanced/src/test/kotlin/com/baeldung/dsl/SqlDslTest.kt

@@ -1,73 +0,0 @@
-package com.baeldung.dsl
-
-import org.assertj.core.api.Assertions.assertThat
-import org.junit.Test
-
-class SqlDslTest {
-
-    @Test
-    fun `when no columns are specified then star is used`() {
-        doTest("select * from table1") {
-            from ("table1")
-        }
-    }
-
-    @Test
-    fun `when no condition is specified then correct query is built`() {
-        doTest("select column1, column2 from table1") {
-            select("column1", "column2")
-            from ("table1")
-        }
-    }
-
-    @Test(expected = Exception::class)
-    fun `when no table is specified then an exception is thrown`() {
-        query {
-            select("column1")
-        }.build()
-    }
-
-    @Test
-    fun `when a list of conditions is specified then it's respected`() {
-        doTest("select * from table1 where (column3 = 4 and column4 is null)") {
-            from ("table1")
-            where {
-                "column3" eq 4
-                "column4" eq null
-            }
-        }
-    }
-
-    @Test
-    fun `when 'or' conditions are specified then they are respected`() {
-        doTest("select * from table1 where (column3 = 4 or column4 is null)") {
-            from ("table1")
-            where {
-                or {
-                    "column3" eq 4
-                    "column4" eq null
-                }
-            }
-        }
-    }
-
-    @Test
-    fun `when either 'and' or 'or' conditions are specified then they are respected`() {
-        doTest("select * from table1 where ((column3 = 4 or column4 is null) and column5 = 42)") {
-            from ("table1")
-            where {
-                and {
-                    or {
-                        "column3" eq 4
-                        "column4" eq null
-                    }
-                    "column5" eq 42
-                }
-            }
-        }
-    }
-
-    private fun doTest(expected: String, sql: SqlSelectBuilder.() -> Unit) {
-        assertThat(query(sql).build()).isEqualTo(expected)
-    }
-}

core-kotlin-modules/core-kotlin-advanced/src/test/kotlin/com/baeldung/reflection/JavaReflectionTest.kt

@@ -1,32 +0,0 @@
-package com.baeldung.reflection
-
-import org.junit.Ignore
-import org.junit.Test
-import org.slf4j.LoggerFactory
-
-@Ignore
-class JavaReflectionTest {
-    private val LOG = LoggerFactory.getLogger(KClassTest::class.java)
-
-    @Test
-    fun listJavaClassMethods() {
-        Exception::class.java.methods
-                .forEach { method -> LOG.info("Method: {}", method) }
-    }
-
-    @Test
-    fun listKotlinClassMethods() {
-        JavaReflectionTest::class.java.methods
-                .forEach { method -> LOG.info("Method: {}", method) }
-    }
-
-    @Test
-    fun listKotlinDataClassMethods() {
-        data class ExampleDataClass(val name: String, var enabled: Boolean)
-
-        ExampleDataClass::class.java.methods
-                .forEach { method -> LOG.info("Method: {}", method) }
-    }
-
-
-}

core-kotlin-modules/core-kotlin-advanced/src/test/kotlin/com/baeldung/reflection/KClassTest.kt

@@ -1,69 +0,0 @@
-package com.baeldung.reflection
-
-import org.junit.Assert
-import org.junit.Ignore
-import org.junit.Test
-import org.slf4j.LoggerFactory
-import java.math.BigDecimal
-import kotlin.reflect.full.*
-
-class KClassTest {
-    private val LOG = LoggerFactory.getLogger(KClassTest::class.java)
-
-    @Test
-    fun testKClassDetails() {
-        val stringClass = String::class
-        Assert.assertEquals("kotlin.String", stringClass.qualifiedName)
-        Assert.assertFalse(stringClass.isData)
-        Assert.assertFalse(stringClass.isCompanion)
-        Assert.assertFalse(stringClass.isAbstract)
-        Assert.assertTrue(stringClass.isFinal)
-        Assert.assertFalse(stringClass.isSealed)
-
-        val listClass = List::class
-        Assert.assertEquals("kotlin.collections.List", listClass.qualifiedName)
-        Assert.assertFalse(listClass.isData)
-        Assert.assertFalse(listClass.isCompanion)
-        Assert.assertTrue(listClass.isAbstract)
-        Assert.assertFalse(listClass.isFinal)
-        Assert.assertFalse(listClass.isSealed)
-    }
-
-    @Test
-    fun testGetRelated() {
-        LOG.info("Companion Object: {}", TestSubject::class.companionObject)
-        LOG.info("Companion Object Instance: {}", TestSubject::class.companionObjectInstance)
-        LOG.info("Object Instance: {}", TestObject::class.objectInstance)
-
-        Assert.assertSame(TestObject, TestObject::class.objectInstance)
-    }
-
-    @Test
-    fun testNewInstance() {
-        val listClass = ArrayList::class
-
-        val list = listClass.createInstance()
-        Assert.assertTrue(list is ArrayList)
-    }
-
-    @Test
-    @Ignore
-    fun testMembers() {
-        val bigDecimalClass = BigDecimal::class
-
-        LOG.info("Constructors: {}", bigDecimalClass.constructors)
-        LOG.info("Functions: {}", bigDecimalClass.functions)
-        LOG.info("Properties: {}", bigDecimalClass.memberProperties)
-        LOG.info("Extension Functions: {}", bigDecimalClass.memberExtensionFunctions)
-    }
-}
-
-class TestSubject {
-    companion object {
-        val name = "TestSubject"
-    }
-}
-
-object TestObject {
-    val answer = 42
-}

core-kotlin-modules/core-kotlin-advanced/src/test/kotlin/com/baeldung/reflection/KMethodTest.kt

@@ -1,88 +0,0 @@
-package com.baeldung.reflection
-
-import org.junit.Assert
-import org.junit.Test
-import java.io.ByteArrayInputStream
-import java.nio.charset.Charset
-import kotlin.reflect.KMutableProperty
-import kotlin.reflect.full.starProjectedType
-
-class KMethodTest {
-
-    @Test
-    fun testCallMethod() {
-        val str = "Hello"
-        val lengthMethod = str::length
-
-        Assert.assertEquals(5, lengthMethod())
-    }
-
-    @Test
-    fun testReturnType() {
-        val str = "Hello"
-        val method = str::byteInputStream
-
-        Assert.assertEquals(ByteArrayInputStream::class.starProjectedType, method.returnType)
-        Assert.assertFalse(method.returnType.isMarkedNullable)
-    }
-
-    @Test
-    fun testParams() {
-        val str = "Hello"
-        val method = str::byteInputStream
-
-        method.isSuspend
-        Assert.assertEquals(1, method.parameters.size)
-        Assert.assertTrue(method.parameters[0].isOptional)
-        Assert.assertFalse(method.parameters[0].isVararg)
-        Assert.assertEquals(Charset::class.starProjectedType, method.parameters[0].type)
-    }
-
-    @Test
-    fun testMethodDetails() {
-        val codePoints = String::codePoints
-        Assert.assertEquals("codePoints", codePoints.name)
-        Assert.assertFalse(codePoints.isSuspend)
-        Assert.assertFalse(codePoints.isExternal)
-        Assert.assertFalse(codePoints.isInline)
-        Assert.assertFalse(codePoints.isOperator)
-
-        val byteInputStream = String::byteInputStream
-        Assert.assertEquals("byteInputStream", byteInputStream.name)
-        Assert.assertFalse(byteInputStream.isSuspend)
-        Assert.assertFalse(byteInputStream.isExternal)
-        Assert.assertTrue(byteInputStream.isInline)
-        Assert.assertFalse(byteInputStream.isOperator)
-    }
-
-    val readOnlyProperty: Int = 42
-    lateinit var mutableProperty: String
-
-    @Test
-    fun testPropertyDetails() {
-        val roProperty = this::readOnlyProperty
-        Assert.assertEquals("readOnlyProperty", roProperty.name)
-        Assert.assertFalse(roProperty.isLateinit)
-        Assert.assertFalse(roProperty.isConst)
-        Assert.assertFalse(roProperty is KMutableProperty<*>)
-
-        val mProperty = this::mutableProperty
-        Assert.assertEquals("mutableProperty", mProperty.name)
-        Assert.assertTrue(mProperty.isLateinit)
-        Assert.assertFalse(mProperty.isConst)
-        Assert.assertTrue(mProperty is KMutableProperty<*>)
-    }
-
-    @Test
-    fun testProperty() {
-        val prop = this::mutableProperty
-
-        Assert.assertEquals(String::class.starProjectedType, prop.getter.returnType)
-
-        prop.set("Hello")
-        Assert.assertEquals("Hello", prop.get())
-
-        prop.setter("World")
-        Assert.assertEquals("World", prop.getter())
-    }
-}

core-kotlin-modules/core-kotlin-advanced/src/test/kotlin/com/baeldung/regex/RegexTest.kt

@@ -1,123 +0,0 @@
-package com.baeldung.regex
-
-import org.junit.Test
-import kotlin.test.*
-
-class RegexTest {
-
-    @Test
-    fun whenRegexIsInstantiated_thenIsEqualToToRegexMethod() {
-        val pattern = """a([bc]+)d?\\"""
-
-        assertEquals(Regex.fromLiteral(pattern).pattern, pattern)
-        assertEquals(pattern, Regex(pattern).pattern)
-        assertEquals(pattern, pattern.toRegex().pattern)
-    }
-
-    @Test
-    fun whenRegexMatches_thenResultIsTrue() {
-        val regex = """a([bc]+)d?""".toRegex()
-
-        assertTrue(regex.containsMatchIn("xabcdy"))
-        assertTrue(regex.matches("abcd"))
-        assertFalse(regex matches "xabcdy")
-    }
-
-    @Test
-    fun givenCompletelyMatchingRegex_whenMatchResult_thenDestructuring() {
-        val regex = """a([bc]+)d?""".toRegex()
-
-        assertNull(regex.matchEntire("xabcdy"))
-
-        val matchResult = regex.matchEntire("abbccbbd")
-
-        assertNotNull(matchResult)
-        assertEquals(matchResult!!.value, matchResult.groupValues[0])
-        assertEquals(matchResult.destructured.toList(), matchResult.groupValues.drop(1))
-        assertEquals("bbccbb", matchResult.destructured.component1())
-        assertNull(matchResult.next())
-    }
-
-    @Test
-    fun givenPartiallyMatchingRegex_whenMatchResult_thenGroups() {
-        val regex = """a([bc]+)d?""".toRegex()
-        var matchResult = regex.find("abcb abbd")
-
-        assertNotNull(matchResult)
-        assertEquals(matchResult!!.value, matchResult.groupValues[0])
-        assertEquals("abcb", matchResult.value)
-        assertEquals(IntRange(0, 3), matchResult.range)
-        assertEquals(listOf("abcb", "bcb"), matchResult.groupValues)
-        assertEquals(matchResult.destructured.toList(), matchResult.groupValues.drop(1))
-
-        matchResult = matchResult.next()
-
-        assertNotNull(matchResult)
-        assertEquals("abbd", matchResult!!.value)
-        assertEquals("bb", matchResult.groupValues[1])
-
-        matchResult = matchResult.next()
-
-        assertNull(matchResult)
-    }
-
-    @Test
-    fun givenPartiallyMatchingRegex_whenMatchResult_thenDestructuring() {
-        val regex = """([\w\s]+) is (\d+) years old""".toRegex()
-        val matchResult = regex.find("Mickey Mouse is 95 years old")
-        val (name, age) = matchResult!!.destructured
-
-        assertEquals("Mickey Mouse", name)
-        assertEquals("95", age)
-    }
-
-    @Test
-    fun givenNonMatchingRegex_whenFindCalled_thenNull() {
-        val regex = """a([bc]+)d?""".toRegex()
-        val matchResult = regex.find("foo")
-
-        assertNull(matchResult)
-    }
-
-    @Test
-    fun givenNonMatchingRegex_whenFindAllCalled_thenEmptySet() {
-        val regex = """a([bc]+)d?""".toRegex()
-        val matchResults = regex.findAll("foo")
-
-        assertNotNull(matchResults)
-        assertTrue(matchResults.none())
-    }
-
-    @Test
-    fun whenReplace_thenReplacement() {
-        val regex = """(red|green|blue)""".toRegex()
-        val beautiful = "Roses are red, Violets are blue"
-        val grim = regex.replace(beautiful, "dark")
-        val shiny = regex.replaceFirst(beautiful, "rainbow")
-
-        assertEquals("Roses are dark, Violets are dark", grim)
-        assertEquals("Roses are rainbow, Violets are blue", shiny)
-    }
-
-    @Test
-    fun whenComplexReplace_thenReplacement() {
-        val regex = """(red|green|blue)""".toRegex()
-        val beautiful = "Roses are red, Violets are blue"
-        val reallyBeautiful = regex.replace(beautiful) {
-            matchResult ->  matchResult.value.toUpperCase() + "!"
-        }
-
-        assertEquals("Roses are RED!, Violets are BLUE!", reallyBeautiful)
-    }
-
-    @Test
-    fun whenSplit_thenList() {
-        val regex = """\W+""".toRegex()
-        val beautiful = "Roses are red, Violets are blue"
-
-        assertEquals(listOf("Roses", "are", "red", "Violets", "are", "blue"), regex.split(beautiful))
-        assertEquals(listOf("Roses", "are", "red", "Violets are blue"), regex.split(beautiful, 4))
-        assertEquals(regex.toPattern().split(beautiful).asList(), regex.split(beautiful))
-    }
-
-}

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

@@ -1,8 +0,0 @@
-## Core Kotlin Annotations
-
-This module contains articles about core Kotlin annotations.
-
-### Relevant articles:
-- [Kotlin Annotations](https://www.baeldung.com/kotlin-annotations)
-- [Guide to Kotlin @JvmField](https://www.baeldung.com/kotlin-jvm-field-annotation)
-- [Guide to JVM Platform Annotations in Kotlin](https://www.baeldung.com/kotlin-jvm-annotations)

core-kotlin-modules/core-kotlin-annotations/pom.xml

@@ -1,41 +0,0 @@
-<?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-annotations</artifactId>
-    <name>core-kotlin-annotations</name>
-    <packaging>jar</packaging>
-
-    <parent>
-        <groupId>com.baeldung.core-kotlin-modules</groupId>
-        <artifactId>core-kotlin-modules</artifactId>
-        <version>1.0.0-SNAPSHOT</version>
-    </parent>
-
-    <dependencies>
-        <dependency>
-            <groupId>org.jetbrains.kotlin</groupId>
-            <artifactId>kotlin-stdlib-jdk8</artifactId>
-            <version>${kotlin.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.assertj</groupId>
-            <artifactId>assertj-core</artifactId>
-            <version>${assertj.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.jetbrains.kotlin</groupId>
-            <artifactId>kotlin-test</artifactId>
-            <version>${kotlin.version}</version>
-            <scope>test</scope>
-        </dependency>
-    </dependencies>
-
-    <properties>
-        <kotlin.version>1.3.30</kotlin.version>
-        <assertj.version>3.10.0</assertj.version>
-    </properties>
-
-</project>

core-kotlin-modules/core-kotlin-annotations/src/main/kotlin/com/baeldung/annotations/Annotations.kt

@@ -1,7 +0,0 @@
-package com.baeldung.annotations
-
-@Target(AnnotationTarget.FIELD)
-annotation class Positive
-
-@Target(AnnotationTarget.FIELD)
-annotation class AllowedNames(val names: Array<String>)

core-kotlin-modules/core-kotlin-annotations/src/main/kotlin/com/baeldung/annotations/Item.kt

@@ -1,3 +0,0 @@
-package com.baeldung.annotations
-
-class Item(@Positive val amount: Float, @AllowedNames(["Alice", "Bob"]) val name: String)

core-kotlin-modules/core-kotlin-annotations/src/main/kotlin/com/baeldung/annotations/Main.kt

@@ -1,7 +0,0 @@
-package com.baeldung.annotations
-
-fun main(args: Array<String>) {
-    val item = Item(amount = 1.0f, name = "Bob")
-    val validator = Validator()
-    println("Is instance valid? ${validator.isValid(item)}")
-}

core-kotlin-modules/core-kotlin-annotations/src/main/kotlin/com/baeldung/annotations/Validator.kt

@@ -1,38 +0,0 @@
-package com.baeldung.annotations
-
-/**
- * Naive annotation-based validator.
- * @author A.Shcherbakov
- */
-class Validator() {
-
-    /**
-     * Return true if every item's property annotated with @Positive is positive and if
-     * every item's property annotated with @AllowedNames has a value specified in that annotation.
-     */
-    fun isValid(item: Item): Boolean {
-        val fields = item::class.java.declaredFields
-        for (field in fields) {
-            field.isAccessible = true
-            for (annotation in field.annotations) {
-                val value = field.get(item)
-                if (field.isAnnotationPresent(Positive::class.java)) {
-                    val amount = value as Float
-                    if (amount < 0) {
-                        return false
-                    }
-                }
-                if (field.isAnnotationPresent(AllowedNames::class.java)) {
-                    val allowedNames = field.getAnnotation(AllowedNames::class.java)?.names
-                    val name = value as String
-                    allowedNames?.let {
-                        if (!it.contains(name)) {
-                            return false
-                        }
-                    }
-                }
-            }
-        }
-        return true
-    }
-}

core-kotlin-modules/core-kotlin-annotations/src/main/kotlin/com/baeldung/jvmannotations/Document.kt

@@ -1,11 +0,0 @@
-package com.baeldung.jvmannotations
-
-import java.util.*
-
-interface Document {
-
-    @JvmDefault
-    fun getTypeDefault() = "document"
-
-    fun getType() = "document"
-}

core-kotlin-modules/core-kotlin-annotations/src/main/kotlin/com/baeldung/jvmannotations/HtmlDocument.java

@@ -1,9 +0,0 @@
-package com.baeldung.jvmannotations;
-
-public class HtmlDocument implements Document {
-
-    @Override
-    public String getType() {
-        return "HTML";
-    }
-}

core-kotlin-modules/core-kotlin-annotations/src/main/kotlin/com/baeldung/jvmannotations/Message.kt

@@ -1,66 +0,0 @@
-@file:JvmName("MessageHelper")
-@file:JvmMultifileClass //used
-package com.baeldung.jvmannotations
-
-import java.util.*
-
-@JvmName("getMyUsername")
-fun getMyName() : String {
-    return "myUserId"
-}
-
-object MessageBroker {
-    @JvmStatic
-    var totalMessagesSent = 0
-
-    const val maxMessageLength = 0
-
-    @JvmStatic
-    fun clearAllMessages() {
-    }
-
-    @JvmStatic
-    @JvmOverloads
-    @Throws(Exception::class)
-    fun findMessages(sender : String, type : String = "text", maxResults : Int = 10) : List<Message> {
-        if(sender.isEmpty()) {
-            throw Exception()
-        }
-        return ArrayList()
-    }
-}
-
-class Message {
-
-    // this would cause a compilation error since sender is immutable
-    // @set:JvmName("setSender")
-    val sender = "myself"
-
-    // this works as name is overridden
-    @JvmName("getSenderName")
-    fun getSender() : String = "from:$sender"
-
-    @get:JvmName("getReceiverName")
-    @set:JvmName("setReceiverName")
-    var receiver : String = ""
-
-    @get:JvmName("getContent")
-    @set:JvmName("setContent")
-    var text = ""
-
-    // generates a warning
-    @get:JvmName("getId")
-    private val id = 0
-
-    @get:JvmName("hasAttachment")
-    var hasAttachment = true
-
-    var isEncrypted = true
-
-    fun setReceivers(receiverNames : List<String>) {
-    }
-
-    @JvmName("setReceiverIds")
-    fun setReceivers(receiverNames : List<Int>) {
-    }
-}

core-kotlin-modules/core-kotlin-annotations/src/main/kotlin/com/baeldung/jvmannotations/MessageConverter.kt

@@ -1,6 +0,0 @@
-@file:JvmMultifileClass
-@file:JvmName("MessageHelper") //applies to all top level functions / variables / constants
-package com.baeldung.jvmannotations
-
-fun convert(message: Message) {
-}

core-kotlin-modules/core-kotlin-annotations/src/main/kotlin/com/baeldung/jvmannotations/TextDocument.kt

@@ -1,16 +0,0 @@
-package com.baeldung.jvmannotations
-
-import java.util.*
-class TextDocument : Document {
-    override fun getType() = "text"
-
-    fun transformList(list : List<Number>) : List<Number> {
-        return list.filter { n -> n.toInt() > 1 }
-    }
-
-    fun transformListInverseWildcards(list : List<@JvmSuppressWildcards Number>) : List<@JvmWildcard Number> {
-        return list.filter { n -> n.toInt() > 1 }
-    }
-
-    var list : List<@JvmWildcard Any> = ArrayList()
-}

core-kotlin-modules/core-kotlin-annotations/src/main/kotlin/com/baeldung/jvmannotations/XmlDocument.kt

@@ -1,5 +0,0 @@
-package com.baeldung.jvmannotations
-
-import java.util.*
-
-class XmlDocument(d : Document) : Document by d

core-kotlin-modules/core-kotlin-annotations/src/main/kotlin/com/baeldung/jvmfield/JvmSample.kt

@@ -1,12 +0,0 @@
-package com.baeldung.jvmfield
-
-class JvmSample(text:String) {
-    @JvmField
-    val sampleText:String = text
-}
-
-class CompanionSample {
-    companion object {
-        @JvmField val MAX_LIMIT = 20
-    }
-}

core-kotlin-modules/core-kotlin-annotations/src/test/kotlin/com/baeldung/annotations/ValidationTest.kt

@@ -1,41 +0,0 @@
-package com.baeldung.annotations
-
-import org.junit.Test
-import kotlin.test.assertTrue
-import kotlin.test.assertFalse
-
-class ValidationTest {
-
-    @Test
-    fun whenAmountIsOneAndNameIsAlice_thenTrue() {
-        assertTrue(Validator().isValid(Item(1f, "Alice")))
-    }
-
-    @Test
-    fun whenAmountIsOneAndNameIsBob_thenTrue() {
-        assertTrue(Validator().isValid(Item(1f, "Bob")))
-    }
-
-
-    @Test
-    fun whenAmountIsMinusOneAndNameIsAlice_thenFalse() {
-        assertFalse(Validator().isValid(Item(-1f, "Alice")))
-    }
-
-    @Test
-    fun whenAmountIsMinusOneAndNameIsBob_thenFalse() {
-        assertFalse(Validator().isValid(Item(-1f, "Bob")))
-    }
-
-    @Test
-    fun whenAmountIsOneAndNameIsTom_thenFalse() {
-        assertFalse(Validator().isValid(Item(1f, "Tom")))
-    }
-
-    @Test
-    fun whenAmountIsMinusOneAndNameIsTom_thenFalse() {
-        assertFalse(Validator().isValid(Item(-1f, "Tom")))
-    }
-
-
-}

core-kotlin-modules/core-kotlin-annotations/src/test/kotlin/com/baeldung/jvmannotations/DocumentTest.kt

@@ -1,20 +0,0 @@
-package com.baeldung.range
-
-import org.junit.Test
-import kotlin.test.assertEquals
-
-import com.baeldung.jvmannotations.*;
-
-class DocumentTest {
-
-    @Test
-    fun testDefaultMethod() {
-
-        val myDocument = TextDocument()
-        val myTextDocument = XmlDocument(myDocument)
-
-        assertEquals("text", myDocument.getType())
-        assertEquals("text", myTextDocument.getType())
-        assertEquals("document", myTextDocument.getTypeDefault())
-    }
-}

core-kotlin-modules/core-kotlin-annotations/src/test/kotlin/com/baeldung/jvmfield/JvmSampleTest.kt

@@ -1,26 +0,0 @@
-package com.baeldung.jvmfield
-
-import org.junit.Before
-import org.junit.Test
-import kotlin.test.assertTrue
-
-class JvmSampleTest {
-
-    var sample = ""
-
-    @Before
-    fun setUp() {
-        sample = JvmSample("Hello!").sampleText
-    }
-
-    @Test
-    fun givenField_whenCheckValue_thenMatchesValue() {
-        assertTrue(sample == "Hello!")
-    }
-
-    @Test
-    fun givenStaticVariable_whenCheckValue_thenMatchesValue() {
-        // Sample when is treated as a static variable
-        assertTrue(CompanionSample.MAX_LIMIT == 20)
-    }
-}

core-kotlin-modules/core-kotlin-collections-2/README.md

@@ -1,7 +0,0 @@
-## Core Kotlin Collections
-
-This module contains articles about core Kotlin collections.
-
-## Relevant articles:
-
-- [Aggregate Operations in Kotlin](https://www.baeldung.com/kotlin/aggregate-operations)

core-kotlin-modules/core-kotlin-collections-2/pom.xml

@@ -1,47 +0,0 @@
-<?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-collections-2</artifactId>
-    <name>core-kotlin-collections-2</name>
-    <packaging>jar</packaging>
-
-    <parent>
-        <groupId>com.baeldung.core-kotlin-modules</groupId>
-        <artifactId>core-kotlin-modules</artifactId>
-        <version>1.0.0-SNAPSHOT</version>
-    </parent>
-
-    <dependencies>
-        <dependency>
-            <groupId>org.jetbrains.kotlin</groupId>
-            <artifactId>kotlin-stdlib-jdk8</artifactId>
-            <version>${kotlin.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.apache.commons</groupId>
-            <artifactId>commons-math3</artifactId>
-            <version>${commons-math3.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.assertj</groupId>
-            <artifactId>assertj-core</artifactId>
-            <version>${assertj.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.jetbrains.kotlin</groupId>
-            <artifactId>kotlin-test</artifactId>
-            <version>${kotlin.version}</version>
-            <scope>test</scope>
-        </dependency>
-    </dependencies>
-
-    <properties>
-        <kotlin.version>1.3.30</kotlin.version>
-        <commons-math3.version>3.6.1</commons-math3.version>
-        <assertj.version>3.10.0</assertj.version>
-    </properties>
-
-</project>

core-kotlin-modules/core-kotlin-collections-2/src/main/kotlin/com/baeldung/aggregate/AggregateOperations.kt

@@ -1,107 +0,0 @@
-package com.baeldung.aggregate
-
-class AggregateOperations {
-    private val numbers = listOf(1, 15, 3, 8)
-
-    fun countList(): Int {
-        return numbers.count()
-    }
-
-    fun sumList(): Int {
-        return numbers.sum()
-    }
-
-    fun averageList(): Double {
-        return numbers.average()
-    }
-
-    fun maximumInList(): Int? {
-        return numbers.max()
-    }
-
-    fun minimumInList(): Int? {
-        return numbers.min()
-    }
-
-    fun maximumByList(): Int? {
-        return numbers.maxBy { it % 5 }
-    }
-
-    fun minimumByList(): Int? {
-        return numbers.minBy { it % 5 }
-    }
-
-    fun maximumWithList(): String? {
-        val strings = listOf("Berlin", "Kolkata", "Prague", "Barcelona")
-        return strings.maxWith(compareBy { it.length % 4 })
-    }
-
-    fun minimumWithList(): String? {
-        val strings = listOf("Berlin", "Kolkata", "Prague", "Barcelona")
-        return strings.minWith(compareBy { it.length % 4 })
-    }
-
-    fun sumByList(): Int {
-        return numbers.sumBy { it * 5 }
-    }
-
-    fun sumByDoubleList(): Double {
-        return numbers.sumByDouble { it.toDouble() / 8 }
-    }
-
-    fun foldList(): Int {
-        return numbers.fold(100) { total, it ->
-            println("total = $total, it = $it")
-            total - it
-        } // ((((100 - 1)-15)-3)-8) = 73
-    }
-
-    fun foldRightList(): Int {
-        return numbers.foldRight(100) { it, total ->
-            println("total = $total, it = $it")
-            total - it
-        }  // ((((100-8)-3)-15)-1) = 73
-    }
-
-    fun foldIndexedList(): Int {
-        return numbers.foldIndexed(100) { index, total, it ->
-            println("total = $total, it = $it, index = $index")
-            if (index.minus(2) >= 0) total - it else total
-        } // ((100 - 3)-8) = 89
-    }
-
-    fun foldRightIndexedList(): Int {
-        return numbers.foldRightIndexed(100) { index, it, total ->
-            println("total = $total, it = $it, index = $index")
-            if (index.minus(2) >= 0) total - it else total
-        } // ((100 - 8)-3) = 89
-    }
-
-    fun reduceList(): Int {
-        return numbers.reduce { total, it ->
-            println("total = $total, it = $it")
-            total - it
-        } // (((1 - 15)-3)-8) = -25
-    }
-
-    fun reduceRightList(): Int {
-        return numbers.reduceRight() { it, total ->
-            println("total = $total, it = $it")
-            total - it
-        } // ((8-3)-15)-1) = -11
-    }
-
-    fun reduceIndexedList(): Int {
-        return numbers.reduceIndexed { index, total, it ->
-            println("total = $total, it = $it, index = $index")
-            if (index.minus(2) >= 0) total - it else total
-        } // ((1-3)-8) = -10
-    }
-
-    fun reduceRightIndexedList(): Int {
-        return numbers.reduceRightIndexed { index, it, total ->
-            println("total = $total, it = $it, index = $index")
-            if (index.minus(2) >= 0) total - it else total
-        } // ((8-3) = 5
-    }
-}

core-kotlin-modules/core-kotlin-collections-2/src/test/kotlin/com/baeldung/aggregate/AggregateOperationsUnitTest.kt

@@ -1,104 +0,0 @@
-package com.baeldung.aggregate
-
-import org.junit.jupiter.api.Test
-import kotlin.test.assertEquals
-
-class AggregateOperationsUnitTest {
-
-    private val classUnderTest: AggregateOperations = AggregateOperations()
-
-    @Test
-    fun whenCountOfList_thenReturnsValue() {
-        assertEquals(4, classUnderTest.countList())
-    }
-
-    @Test
-    fun whenSumOfList_thenReturnsTotalValue() {
-        assertEquals(27, classUnderTest.sumList())
-    }
-
-    @Test
-    fun whenAverageOfList_thenReturnsValue() {
-        assertEquals(6.75, classUnderTest.averageList())
-    }
-
-    @Test
-    fun whenMaximumOfList_thenReturnsMaximumValue() {
-        assertEquals(15, classUnderTest.maximumInList())
-    }
-
-    @Test
-    fun whenMinimumOfList_thenReturnsMinimumValue() {
-        assertEquals(1, classUnderTest.minimumInList())
-    }
-
-    @Test
-    fun whenMaxByList_thenReturnsLargestValue() {
-        assertEquals(3, classUnderTest.maximumByList())
-    }
-
-    @Test
-    fun whenMinByList_thenReturnsSmallestValue() {
-        assertEquals(15, classUnderTest.minimumByList())
-    }
-
-    @Test
-    fun whenMaxWithList_thenReturnsLargestValue(){
-        assertEquals("Kolkata", classUnderTest.maximumWithList())
-    }
-
-    @Test
-    fun whenMinWithList_thenReturnsSmallestValue(){
-        assertEquals("Barcelona", classUnderTest.minimumWithList())
-    }
-
-    @Test
-    fun whenSumByList_thenReturnsIntegerValue(){
-        assertEquals(135, classUnderTest.sumByList())
-    }
-
-    @Test
-    fun whenSumByDoubleList_thenReturnsDoubleValue(){
-        assertEquals(3.375, classUnderTest.sumByDoubleList())
-    }
-
-    @Test
-    fun whenFoldList_thenReturnsValue(){
-        assertEquals(73, classUnderTest.foldList())
-    }
-
-    @Test
-    fun whenFoldRightList_thenReturnsValue(){
-        assertEquals(73, classUnderTest.foldRightList())
-    }
-
-    @Test
-    fun whenFoldIndexedList_thenReturnsValue(){
-        assertEquals(89, classUnderTest.foldIndexedList())
-    }
-
-    @Test
-    fun whenFoldRightIndexedList_thenReturnsValue(){
-        assertEquals(89, classUnderTest.foldRightIndexedList())
-    }
-
-    @Test
-    fun whenReduceList_thenReturnsValue(){
-        assertEquals(-25, classUnderTest.reduceList())
-    }
-
-    @Test
-    fun whenReduceRightList_thenReturnsValue(){
-        assertEquals(-11, classUnderTest.reduceRightList())
-    }
-
-    @Test
-    fun whenReduceIndexedList_thenReturnsValue(){
-        assertEquals(-10, classUnderTest.reduceIndexedList())
-    }
-
-    @Test
-    fun whenReduceRightIndexedList_thenReturnsValue(){
-        assertEquals(5, classUnderTest.reduceRightIndexedList())
-    }
-}

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

@@ -1,16 +0,0 @@
-## Core Kotlin Collections
-
-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)
-- [Converting a List to Map in Kotlin](https://www.baeldung.com/kotlin-list-to-map)
-- [Filtering Kotlin Collections](https://www.baeldung.com/kotlin-filter-collection)
-- [Collection Transformations in Kotlin](https://www.baeldung.com/kotlin-collection-transformations)
-- [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/pom.xml

@@ -1,47 +0,0 @@
-<?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-collections</artifactId>
-    <name>core-kotlin-collections</name>
-    <packaging>jar</packaging>
-
-    <parent>
-        <groupId>com.baeldung.core-kotlin-modules</groupId>
-        <artifactId>core-kotlin-modules</artifactId>
-        <version>1.0.0-SNAPSHOT</version>
-    </parent>
-
-    <dependencies>
-        <dependency>
-            <groupId>org.jetbrains.kotlin</groupId>
-            <artifactId>kotlin-stdlib-jdk8</artifactId>
-            <version>${kotlin.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.apache.commons</groupId>
-            <artifactId>commons-math3</artifactId>
-            <version>${commons-math3.version}</version>
-        </dependency>
-        <dependency>
-            <groupId>org.assertj</groupId>
-            <artifactId>assertj-core</artifactId>
-            <version>${assertj.version}</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.jetbrains.kotlin</groupId>
-            <artifactId>kotlin-test</artifactId>
-            <version>${kotlin.version}</version>
-            <scope>test</scope>
-        </dependency>
-    </dependencies>
-
-    <properties>
-        <kotlin.version>1.3.30</kotlin.version>
-        <commons-math3.version>3.6.1</commons-math3.version>
-        <assertj.version>3.10.0</assertj.version>
-    </properties>
-
-</project>

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

@@ -1,33 +0,0 @@
-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-collections/src/main/kotlin/com/baeldung/kotlin/collections/ListExample.kt

@@ -1,204 +0,0 @@
-package com.baeldung.kotlin.collections
-
-import kotlin.collections.List
-
-class ListExample {
-
-    private val countries = listOf("Germany", "India", "Japan", "Brazil", "Australia")
-    private val cities = mutableListOf("Berlin", "Calcutta", "Seoul", "Sao Paulo", "Sydney")
-
-    fun createList(): List<String> {
-        val countryList = listOf("Germany", "India", "Japan", "Brazil")
-        return countryList
-    }
-
-    fun createMutableList(): MutableList<String> {
-        val cityList = mutableListOf("Berlin", "Calcutta", "Seoul", "Sao Paulo")
-        return cityList
-    }
-
-    fun iterateUsingForEachLoop(): List<Int> {
-        val countryLength = mutableListOf<Int>()
-        countries.forEach { it ->
-            print("$it ")
-            println(" Length: ${it.length}")
-            countryLength.add(it.length)
-        }
-        return countryLength
-    }
-
-    fun iterateUsingForLoop(): List<Int> {
-        val countryLength = mutableListOf<Int>()
-        for (country in countries) {
-            print("$country ")
-            println(" Length: ${country.length}")
-            countryLength.add(country.length)
-        }
-        return countryLength
-    }
-
-    fun iterateUsingForLoopRange(): List<Int> {
-        val countryLength = mutableListOf<Int>()
-        for (i in 0 until countries.size) {
-            print("${countries[i]} ")
-            println(" Length: ${countries[i].length}")
-            countryLength.add(countries[i].length)
-        }
-        return countryLength
-    }
-
-    fun iterateUsingForEachIndexedLoop(): List<Int> {
-        val countryLength = mutableListOf<Int>()
-        countries.forEachIndexed { i, e ->
-            println("country[$i] = $e")
-            print(" Index: $i")
-            println(" Length: ${e.length}")
-            countryLength.add(e.length)
-        }
-        return countryLength
-    }
-
-    fun iterateUsingListIterator() {
-        val iterator = countries.listIterator()
-        while (iterator.hasNext()) {
-            val country = iterator.next()
-            print("$country ")
-        }
-        println()
-
-        while (iterator.hasPrevious()) {
-            println("Index: ${iterator.previousIndex()}")
-        }
-    }
-
-    fun iterateUsingIterator() {
-        val iterator = cities.iterator()
-        iterator.next()
-        iterator.remove()
-        println(cities)
-    }
-
-    fun iterateUsingMutableListIterator() {
-        val iterator = cities.listIterator(1)
-        iterator.next()
-        iterator.add("London")
-        iterator.next()
-        iterator.set("Milan")
-        println(cities)
-    }
-
-    fun retrieveElementsInList(): String {
-        println(countries[2])
-        return countries[2]
-    }
-
-    fun retrieveElementsUsingGet(): String {
-        println(countries.get(3))
-        return countries.get(3)
-    }
-
-    fun retrieveElementsFirstAndLast(): String? {
-        println(countries.first())
-        println(countries.last())
-        println(countries.first { it.length > 7 })
-        println(countries.last { it.startsWith("J") })
-        println(countries.firstOrNull { it.length > 8 })
-        return countries.firstOrNull { it.length > 8 }
-    }
-
-    fun retrieveSubList(): List<String> {
-        val subList = countries.subList(1, 4)
-        println(subList)
-        return subList
-    }
-
-    fun retrieveListSliceUsingIndices(): List<String> {
-        val sliceList = countries.slice(1..4)
-        println(sliceList)
-        return sliceList
-    }
-
-    fun retrieveListSliceUsingIndicesList(): List<String> {
-        val sliceList = countries.slice(listOf(1, 4))
-        println(sliceList)
-        return sliceList
-    }
-
-    fun countList(): Int {
-        val count = countries.count()
-        println(count)
-        return count
-    }
-
-    fun countListUsingPredicate(): Int {
-        val count = countries.count { it.length > 5 }
-        println(count)
-        return count
-    }
-
-    fun countListUsingProperty(): Int {
-        val size = countries.size
-        println(size)
-        return size
-    }
-
-    fun addToList(): List<String> {
-        cities.add("Barcelona")
-        println(cities)
-        cities.add(3, "London")
-        println(cities)
-        cities.addAll(listOf("Singapore", "Moscow"))
-        println(cities)
-        cities.addAll(2, listOf("Prague", "Amsterdam"))
-        println(cities)
-        return cities
-    }
-
-    fun removeFromList(): List<String> {
-        cities.remove("Seoul")
-        println(cities)
-        cities.removeAt(1)
-        println(cities)
-        return cities
-    }
-
-    fun replaceFromList(): List<String> {
-        cities.set(3, "Prague")
-        println(cities)
-        cities[4] = "Moscow"
-        println(cities)
-        cities.fill("Barcelona")
-        println(cities)
-        return cities
-    }
-
-    fun sortMutableList(): List<String> {
-        cities.sort()
-        println(cities)
-        cities.sortDescending()
-        println(cities)
-        return cities
-    }
-
-    fun sortList(): List<String> {
-        val sortedCountries = countries.sorted()
-        println("countries = $countries")
-        println("sortedCountries = $sortedCountries")
-        val sortedCountriesDescending = countries.sortedDescending()
-        println("countries = $countries")
-        println("sortedCountriesDescending = $sortedCountriesDescending")
-        return sortedCountriesDescending
-    }
-
-    fun checkOneElementInList(): Boolean {
-        return countries.contains("Germany")
-    }
-
-    fun checkOneElementInListUsingOperator(): Boolean {
-        return "Spain" in countries
-    }
-
-    fun checkElementsInList(): Boolean {
-        return cities.containsAll(listOf("Calcutta", "Sao Paulo", "Sydney"))
-    }
-}

core-kotlin-modules/core-kotlin-collections/src/main/kotlin/com/baeldung/sorting/SortingExample.kt

@@ -1,42 +0,0 @@
-package com.baeldung.sorting
-
-fun sortMethodUsage() {
-    val sortedValues = mutableListOf(1, 2, 7, 6, 5, 6)
-    sortedValues.sort()
-    println(sortedValues)
-}
-
-fun sortByMethodUsage() {
-    val sortedValues = mutableListOf(1 to "a", 2 to "b", 7 to "c", 6 to "d", 5 to "c", 6 to "e")
-    sortedValues.sortBy { it.second }
-    println(sortedValues)
-}
-
-fun sortWithMethodUsage() {
-    val sortedValues = mutableListOf(1 to "a", 2 to "b", 7 to "c", 6 to "d", 5 to "c", 6 to "e")
-    sortedValues.sortWith(compareBy({it.second}, {it.first}))
-    println(sortedValues)
-}
-
-fun <T : kotlin.Comparable<T>> getSimpleComparator() : Comparator<T> {
-    val ascComparator = naturalOrder<T>()
-    return ascComparator
-}
-
-fun getComplexComparator() {
-    val complexComparator = compareBy<Pair<Int, String>>({it.first}, {it.second})
-}
-
-fun nullHandlingUsage() {
-    val sortedValues = mutableListOf(1 to "a", 2 to null, 7 to "c", 6 to "d", 5 to "c", 6 to "e")
-    sortedValues.sortWith(nullsLast(compareBy { it.second }))
-    println(sortedValues)
-}
-
-fun extendedComparatorUsage() {
-    val students = mutableListOf(21 to "Helen", 21 to "Tom", 20 to "Jim")
-
-    val ageComparator = compareBy<Pair<Int, String?>> {it.first}
-    val ageAndNameComparator = ageComparator.thenByDescending {it.second}
-    println(students.sortedWith(ageAndNameComparator))
-}

core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/collections/CollectionsTest.kt

@@ -1,212 +0,0 @@
-package com.baeldung.collections
-
-import org.assertj.core.api.Assertions.assertThat
-import org.junit.Test
-import kotlin.test.assertEquals
-import kotlin.test.assertFalse
-import kotlin.test.assertTrue
-
-class CollectionsTest {
-
-    @Test
-    fun whenUseDifferentCollections_thenSuccess() {
-        val theList = listOf("one", "two", "three")
-        assertTrue(theList.contains("two"))
-
-        val theMutableList = mutableListOf("one", "two", "three")
-        theMutableList.add("four")
-        assertTrue(theMutableList.contains("four"))
-
-        val theSet = setOf("one", "two", "three")
-        assertTrue(theSet.contains("three"))
-
-        val theMutableSet = mutableSetOf("one", "two", "three")
-        theMutableSet.add("four")
-        assertTrue(theMutableSet.contains("four"))
-
-        val theMap = mapOf(1 to "one", 2 to "two", 3 to "three")
-        assertEquals(theMap[2], "two")
-
-        val theMutableMap = mutableMapOf(1 to "one", 2 to "two", 3 to "three")
-        theMutableMap[4] = "four"
-        assertEquals(theMutableMap[4], "four")
-    }
-
-    @Test
-    fun whenSliceCollection_thenSuccess() {
-        val theList = listOf("one", "two", "three")
-        val resultList = theList.slice(1..2)
-
-        assertEquals(2, resultList.size)
-        assertTrue(resultList.contains("two"))
-    }
-
-    @Test
-    fun whenJoinTwoCollections_thenSuccess() {
-        val firstList = listOf("one", "two", "three")
-        val secondList = listOf("four", "five", "six")
-        val resultList = firstList + secondList
-
-        assertEquals(6, resultList.size)
-        assertTrue(resultList.contains("two"))
-        assertTrue(resultList.contains("five"))
-    }
-
-    @Test
-    fun whenFilterNullValues_thenSuccess() {
-        val theList = listOf("one", null, "two", null, "three")
-        val resultList = theList.filterNotNull()
-
-        assertEquals(3, resultList.size)
-    }
-
-    @Test
-    fun whenFilterNonPositiveValues_thenSuccess() {
-        val theList = listOf(1, 2, -3, -4, 5, -6)
-        val resultList = theList.filter { it > 0 }
-        //val resultList = theList.filter{ x -> x > 0}
-
-        assertEquals(3, resultList.size)
-        assertTrue(resultList.contains(1))
-        assertFalse(resultList.contains(-4))
-    }
-
-    @Test
-    fun whenDropFirstItems_thenRemoved() {
-        val theList = listOf("one", "two", "three", "four")
-        val resultList = theList.drop(2)
-
-        assertEquals(2, resultList.size)
-        assertFalse(resultList.contains("one"))
-        assertFalse(resultList.contains("two"))
-    }
-
-    @Test
-    fun whenDropFirstItemsBasedOnCondition_thenRemoved() {
-        val theList = listOf("one", "two", "three", "four")
-        val resultList = theList.dropWhile { it.length < 4 }
-
-        assertEquals(2, resultList.size)
-        assertFalse(resultList.contains("one"))
-        assertFalse(resultList.contains("two"))
-    }
-
-    @Test
-    fun whenExcludeItems_thenRemoved() {
-        val firstList = listOf("one", "two", "three")
-        val secondList = listOf("one", "three")
-        val resultList = firstList - secondList
-
-        assertEquals(1, resultList.size)
-        assertTrue(resultList.contains("two"))
-    }
-
-    @Test
-    fun whenSearchForExistingItem_thenFound() {
-        val theList = listOf("one", "two", "three")
-
-        assertTrue("two" in theList)
-    }
-
-    @Test
-    fun whenGroupItems_thenSuccess() {
-        val theList = listOf(1, 2, 3, 4, 5, 6)
-        val resultMap = theList.groupBy { it % 3 }
-
-        assertEquals(3, resultMap.size)
-        print(resultMap[1])
-        assertTrue(resultMap[1]!!.contains(1))
-        assertTrue(resultMap[2]!!.contains(5))
-    }
-
-    @Test
-    fun whenApplyFunctionToAllItems_thenSuccess() {
-        val theList = listOf(1, 2, 3, 4, 5, 6)
-        val resultList = theList.map { it * it }
-        print(resultList)
-        assertEquals(4, resultList[1])
-        assertEquals(9, resultList[2])
-    }
-
-    @Test
-    fun whenApplyMultiOutputFunctionToAllItems_thenSuccess() {
-        val theList = listOf("John", "Tom")
-        val resultList = theList.flatMap { it.toLowerCase().toList() }
-        print(resultList)
-        assertEquals(7, resultList.size)
-        assertTrue(resultList.contains('j'))
-    }
-
-    @Test
-    fun whenApplyFunctionToAllItemsWithStartingValue_thenSuccess() {
-        val theList = listOf(1, 2, 3, 4, 5, 6)
-        val finalResult = theList.fold(1000, { oldResult, currentItem -> oldResult + (currentItem * currentItem) })
-        print(finalResult)
-        assertEquals(1091, finalResult)
-    }
-
-    @Test
-    fun whenApplyingChunked_thenShouldBreakTheCollection() {
-        val theList = listOf(1, 2, 3, 4, 5)
-        val chunked = theList.chunked(2)
-
-        assertThat(chunked.size).isEqualTo(3)
-        assertThat(chunked.first()).contains(1, 2)
-        assertThat(chunked[1]).contains(3, 4)
-        assertThat(chunked.last()).contains(5)
-    }
-
-    @Test
-    fun whenApplyingChunkedWithTransformation_thenShouldBreakTheCollection() {
-        val theList = listOf(1, 2, 3, 4, 5)
-        val chunked = theList.chunked(3) { it.joinToString(", ") }
-
-        assertThat(chunked.size).isEqualTo(2)
-        assertThat(chunked.first()).isEqualTo("1, 2, 3")
-        assertThat(chunked.last()).isEqualTo("4, 5")
-    }
-
-    @Test
-    fun whenApplyingWindowed_thenShouldCreateSlidingWindowsOfElements() {
-        val theList = (1..6).toList()
-        val windowed = theList.windowed(3)
-
-        assertThat(windowed.size).isEqualTo(4)
-        assertThat(windowed.first()).contains(1, 2, 3)
-        assertThat(windowed[1]).contains(2, 3, 4)
-        assertThat(windowed[2]).contains(3, 4, 5)
-        assertThat(windowed.last()).contains(4, 5, 6)
-    }
-
-    @Test
-    fun whenApplyingWindowedWithTwoSteps_thenShouldCreateSlidingWindowsOfElements() {
-        val theList = (1..6).toList()
-        val windowed = theList.windowed(size = 3, step = 2)
-
-        assertThat(windowed.size).isEqualTo(2)
-        assertThat(windowed.first()).contains(1, 2, 3)
-        assertThat(windowed.last()).contains(3, 4, 5)
-    }
-
-    @Test
-    fun whenApplyingPartialWindowedWithTwoSteps_thenShouldCreateSlidingWindowsOfElements() {
-        val theList = (1..6).toList()
-        val windowed = theList.windowed(size = 3, step = 2, partialWindows = true)
-
-        assertThat(windowed.size).isEqualTo(3)
-        assertThat(windowed.first()).contains(1, 2, 3)
-        assertThat(windowed[1]).contains(3, 4, 5)
-        assertThat(windowed.last()).contains(5, 6)
-    }
-
-    @Test
-    fun whenApplyingTransformingWindows_thenShouldCreateSlidingWindowsOfElements() {
-        val theList = (1..6).toList()
-        val windowed = theList.windowed(size = 3, step = 2, partialWindows = true) { it.joinToString(", ") }
-
-        assertThat(windowed.size).isEqualTo(3)
-        assertThat(windowed.first()).isEqualTo("1, 2, 3")
-        assertThat(windowed[1]).isEqualTo("3, 4, 5")
-        assertThat(windowed.last()).isEqualTo("5, 6")
-    }
-}

core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/collections/transformations/AssociateUnitTest.kt

@@ -1,48 +0,0 @@
-package com.baeldung.collections.transformations
-
-import org.junit.Assert.assertEquals
-import org.junit.Test
-
-class AssociateUnitTest {
-    @Test
-    fun testToMap() {
-        val input = listOf(Pair("one", 1), Pair("two", 2))
-        val map = input.toMap()
-        assertEquals(mapOf("one" to 1, "two" to 2), map)
-    }
-
-    @Test
-    fun testAssociateWith() {
-        val inputs = listOf("Hi", "there")
-        val map = inputs.associateWith { k -> k.length }
-        assertEquals(mapOf("Hi" to 2, "there" to 5), map)
-    }
-
-    @Test
-    fun testAssociateBy() {
-        val inputs = listOf("Hi", "there")
-        val map = inputs.associateBy { v -> v.length }
-        assertEquals(mapOf(2 to "Hi", 5 to "there"), map)
-    }
-
-    @Test
-    fun testAssociate() {
-        val inputs = listOf("Hi", "there")
-        val map = inputs.associate { e -> Pair(e.toUpperCase(), e.reversed()) }
-        assertEquals(mapOf("HI" to "iH", "THERE" to "ereht"), map)
-    }
-
-    @Test
-    fun testAssociateByDuplicateKeys() {
-        val inputs = listOf("one", "two")
-        val map = inputs.associateBy { v -> v.length }
-        assertEquals(mapOf(3 to "two"), map)
-    }
-
-    @Test
-    fun testGroupBy() {
-        val inputs = listOf("one", "two", "three")
-        val map = inputs.groupBy { v -> v.length }
-        assertEquals(mapOf(3 to listOf("one", "two"), 5 to listOf("three")), map)
-    }
-}

core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/collections/transformations/FilterUnitTest.kt

@@ -1,43 +0,0 @@
-package com.baeldung.collections.transformations
-
-import org.junit.Assert.assertEquals
-import org.junit.Test
-
-class FilterUnitTest {
-    @Test
-    fun testFilterWithLambda() {
-        val input = listOf(1, 2, 3, 4, 5)
-        val filtered = input.filter { it <= 3 }
-        assertEquals(listOf(1, 2, 3), filtered)
-    }
-
-    @Test
-    fun testFilterWithMethodReference() {
-        val input = listOf(1, 2, 3, 4, 5)
-        val filtered = input.filter(this::isSmall)
-        assertEquals(listOf(1, 2, 3), filtered)
-    }
-
-    @Test
-    fun testFilterNotWithMethodReference() {
-        val input = listOf(1, 2, 3, 4, 5)
-        val filtered = input.filterNot(this::isSmall)
-        assertEquals(listOf(4, 5), filtered)
-    }
-
-    @Test
-    fun testFilterIndexed() {
-        val input = listOf(5, 4, 3, 2, 1)
-        val filtered = input.filterIndexed { index, element -> index < 3 }
-        assertEquals(listOf(5, 4, 3), filtered)
-    }
-
-    @Test
-    fun testFilterNotNull() {
-        val nullable: List<String?> = listOf("Hello", null, "World")
-        val nonnull: List<String> = nullable.filterNotNull()
-        assertEquals(listOf("Hello", "World"), nonnull)
-    }
-
-    private fun isSmall(i: Int) = i <= 3
-}

core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/collections/transformations/FlattenUnitTest.kt

@@ -1,21 +0,0 @@
-package com.baeldung.collections.transformations
-
-import org.junit.Assert.assertEquals
-import org.junit.Test
-
-class FlattenUnitTest {
-    @Test
-    fun testFlatten() {
-        val inputs = listOf("one", "two", "three")
-        val characters = inputs.map(String::toList)
-        val flattened = characters.flatten();
-        assertEquals(listOf('o', 'n', 'e', 't', 'w', 'o', 't', 'h', 'r', 'e', 'e'), flattened)
-    }
-
-    @Test
-    fun testFlatMap() {
-        val inputs = listOf("one", "two", "three")
-        val characters = inputs.flatMap(String::toList)
-        assertEquals(listOf('o', 'n', 'e', 't', 'w', 'o', 't', 'h', 'r', 'e', 'e'), characters)
-    }
-}

core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/collections/transformations/JoinToUnitTest.kt

@@ -1,46 +0,0 @@
-package com.baeldung.collections.transformations
-
-import org.junit.Assert.assertEquals
-import org.junit.Test
-
-class JoinToUnitTest {
-    @Test
-    fun testJoinToString() {
-        val inputs = listOf("Jan", "Feb", "Mar", "Apr", "May")
-
-        val simpleString = inputs.joinToString()
-        assertEquals("Jan, Feb, Mar, Apr, May", simpleString)
-
-        val detailedString = inputs.joinToString(separator = ",", prefix="Months: ", postfix=".")
-        assertEquals("Months: Jan,Feb,Mar,Apr,May.", detailedString)
-    }
-
-    @Test
-    fun testJoinToStringLimits() {
-        val inputs = listOf("Jan", "Feb", "Mar", "Apr", "May")
-
-        val simpleString = inputs.joinToString(limit = 3)
-        assertEquals("Jan, Feb, Mar, ...", simpleString)
-    }
-
-    @Test
-    fun testJoinToStringTransform() {
-        val inputs = listOf("Jan", "Feb", "Mar", "Apr", "May")
-
-        val simpleString = inputs.joinToString(transform = String::toUpperCase)
-        assertEquals("JAN, FEB, MAR, APR, MAY", simpleString)
-    }
-
-    @Test
-    fun testJoinTo() {
-        val inputs = listOf("Jan", "Feb", "Mar", "Apr", "May")
-
-        val output = StringBuilder()
-        output.append("My ")
-                .append(inputs.size)
-                .append(" elements: ")
-        inputs.joinTo(output)
-
-        assertEquals("My 5 elements: Jan, Feb, Mar, Apr, May", output.toString())
-    }
-}

core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/collections/transformations/MapUnitTest.kt

@@ -1,53 +0,0 @@
-package com.baeldung.collections.transformations
-
-import org.junit.Assert.assertEquals
-import org.junit.Test
-
-class MapUnitTest {
-    @Test
-    fun testMapWithLambda() {
-        val input = listOf("one", "two", "three")
-
-        val reversed = input.map { it.reversed() }
-        assertEquals(listOf("eno", "owt", "eerht"), reversed)
-
-        val lengths = input.map { it.length }
-        assertEquals(listOf(3, 3, 5), lengths)
-    }
-
-    @Test
-    fun testMapIndexed() {
-        val input = listOf(3, 2, 1)
-        val result = input.mapIndexed { index, value -> index * value }
-        assertEquals(listOf(0, 2, 2), result)
-    }
-
-    @Test
-    fun testMapNotNull() {
-        val input = listOf(1, 2, 3, 4, 5)
-        val smallSquares = input.mapNotNull {
-            if (it <= 3) {
-                it * it
-            } else {
-                null
-            }
-        }
-        assertEquals(listOf(1, 4, 9), smallSquares)
-    }
-
-    @Test
-    fun mapMapKeys() {
-        val inputs = mapOf("one" to 1, "two" to 2, "three" to 3)
-
-        val uppercases = inputs.mapKeys { it.key.toUpperCase() }
-        assertEquals(mapOf("ONE" to 1, "TWO" to 2, "THREE" to 3), uppercases)
-    }
-
-    @Test
-    fun mapMapValues() {
-        val inputs = mapOf("one" to 1, "two" to 2, "three" to 3)
-
-        val squares = inputs.mapValues { it.value * it.value }
-        assertEquals(mapOf("one" to 1, "two" to 4, "three" to 9), squares)
-    }
-}

core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/collections/transformations/ReduceUnitTest.kt

@@ -1,22 +0,0 @@
-package com.baeldung.collections.transformations
-
-import org.junit.Assert.assertEquals
-import org.junit.Test
-
-class ReduceUnitTest {
-    @Test
-    fun testJoinToStringAsReduce() {
-        val inputs = listOf("Jan", "Feb", "Mar", "Apr", "May")
-
-        val result = inputs.reduce { acc, next -> "$acc, $next" }
-        assertEquals("Jan, Feb, Mar, Apr, May", result)
-    }
-
-    @Test
-    fun testFoldToLength() {
-        val inputs = listOf("Jan", "Feb", "Mar", "Apr", "May")
-
-        val result = inputs.fold(0) { acc, next -> acc + next.length }
-        assertEquals(15, result)
-    }
-}

core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/collections/transformations/ZipUnitTest.kt

@@ -1,34 +0,0 @@
-package com.baeldung.collections.transformations
-
-import org.junit.Assert.assertEquals
-import org.junit.Test
-
-class ZipUnitTest {
-    @Test
-    fun testZip() {
-        val left = listOf("one", "two", "three")
-        val right = listOf(1, 2, 3)
-        val zipped = left.zip(right)
-        assertEquals (listOf(Pair("one", 1), Pair("two", 2), Pair("three", 3)), zipped)
-    }
-
-    @Test
-    fun testZipShort() {
-        val left = listOf("one", "two")
-        val right = listOf(1, 2, 3)
-        val zipped = left.zip(right)
-        assertEquals (listOf(Pair("one", 1), Pair("two", 2)), zipped)
-    }
-
-    @Test
-    fun testUnzip() {
-        val left = listOf("one", "two", "three")
-        val right = listOf(1, 2, 3)
-        val zipped = left.zip(right)
-
-        val (newLeft, newRight) = zipped.unzip()
-        assertEquals(left, newLeft)
-        assertEquals(right, newRight)
-    }
-
-}

core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/filter/ChunkedTest.kt

@@ -1,39 +0,0 @@
-package com.baeldung.filter
-
-import org.junit.jupiter.api.Assertions.assertIterableEquals
-import org.junit.jupiter.api.Test
-
-internal class ChunkedTest {
-
-    @Test
-    fun givenDNAFragmentString_whenChunking_thenProduceListOfChunks() {
-        val dnaFragment = "ATTCGCGGCCGCCAA"
-
-        val fragments = dnaFragment.chunked(3)
-
-        assertIterableEquals(listOf("ATT", "CGC", "GGC", "CGC", "CAA"), fragments)
-    }
-
-    @Test
-    fun givenDNAString_whenChunkingWithTransformer_thenProduceTransformedList() {
-        val codonTable = mapOf("ATT" to "Isoleucine", "CAA" to "Glutamine", "CGC" to "Arginine", "GGC" to "Glycine")
-        val dnaFragment = "ATTCGCGGCCGCCAA"
-
-        val proteins = dnaFragment.chunked(3) { codon ->
-            codonTable[codon.toString()] ?: error("Unknown codon")
-        }
-
-        assertIterableEquals(listOf("Isoleucine", "Arginine", "Glycine", "Arginine", "Glutamine"), proteins)
-    }
-
-    @Test
-    fun givenListOfValues_whenChunking_thenProduceListOfArrays() {
-        val whole = listOf(1, 4, 7, 4753, 2, 34, 62, 76, 5868, 0)
-        val chunks = whole.chunked(6)
-
-        val expected = listOf(listOf(1, 4, 7, 4753, 2, 34), listOf(62, 76, 5868, 0))
-
-        assertIterableEquals(expected, chunks)
-    }
-
-}

core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/filter/DistinctTest.kt

@@ -1,71 +0,0 @@
-package com.baeldung.filter
-
-import org.junit.jupiter.api.Assertions.assertIterableEquals
-import org.junit.jupiter.api.Test
-
-internal class DistinctTest {
-    data class SmallClass(val key: String, val num: Int)
-
-    @Test
-    fun whenApplyingDistinct_thenReturnListOfNoDuplicateValues() {
-        val array = arrayOf(1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 5, 6, 7, 8, 9)
-        val result = array.distinct()
-        val expected = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9)
-
-        assertIterableEquals(expected, result)
-    }
-
-    @Test
-    fun givenArrayOfClassObjects_whenApplyingDistinctOnClassProperty_thenReturnListDistinctOnThatValue() {
-
-        val original = arrayOf(
-                SmallClass("key1", 1),
-                SmallClass("key2", 2),
-                SmallClass("key3", 3),
-                SmallClass("key4", 3),
-                SmallClass("er", 9),
-                SmallClass("er", 10),
-                SmallClass("er", 11))
-
-        val actual = original.distinctBy { it.key }
-
-        val expected = listOf(
-                SmallClass("key1", 1),
-                SmallClass("key2", 2),
-                SmallClass("key3", 3),
-                SmallClass("key4", 3),
-                SmallClass("er", 9))
-
-
-        assertIterableEquals(expected, actual)
-    }
-
-    @Test
-    fun givenArrayOfClassObjects_whenApplyingComplicatedSelector_thenReturnFirstElementToMatchEachSelectorValue() {
-        val array = arrayOf(
-                SmallClass("key1", 1),
-                SmallClass("key2", 2),
-                SmallClass("key3", 3),
-                SmallClass("key4", 3),
-                SmallClass("er", 9),
-                SmallClass("er", 10),
-                SmallClass("er", 11),
-                SmallClass("er", 11),
-                SmallClass("er", 91),
-                SmallClass("blob", 22),
-                SmallClass("dob", 27),
-                SmallClass("high", 201_434_314))
-
-        val actual = array.distinctBy { Math.floor(it.num / 10.0) }
-
-        val expected = listOf(
-                SmallClass("key1", 1),
-                SmallClass("er", 10),
-                SmallClass("er", 91),
-                SmallClass("blob", 22),
-                SmallClass("high", 201_434_314))
-
-        assertIterableEquals(expected, actual)
-    }
-
-}

core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/filter/DropTest.kt

@@ -1,53 +0,0 @@
-package com.baeldung.filter
-
-import org.junit.jupiter.api.Assertions.assertIterableEquals
-import org.junit.jupiter.api.Test
-
-internal class DropTest {
-
-    @Test
-    fun whenDroppingFirstTwoItemsOfArray_thenTwoLess() {
-        val array = arrayOf(1, 2, 3, 4)
-        val result = array.drop(2)
-        val expected = listOf(3, 4)
-
-        assertIterableEquals(expected, result)
-    }
-
-    @Test
-    fun whenDroppingMoreItemsOfArray_thenEmptyList() {
-        val array = arrayOf(1, 2, 3, 4)
-        val result = array.drop(5)
-        val expected = listOf<Int>()
-
-        assertIterableEquals(expected, result)
-    }
-
-    @Test
-    fun givenArray_whenDroppingLastElement_thenReturnListWithoutLastElement() {
-        val array = arrayOf("1", "2", "3", "4")
-        val result = array.dropLast(1)
-        val expected = listOf("1", "2", "3")
-
-        assertIterableEquals(expected, result)
-    }
-
-    @Test
-    fun givenArrayOfFloats_whenDroppingLastUntilPredicateIsFalse_thenReturnSubsetListOfFloats() {
-        val array = arrayOf(1f, 1f, 1f, 1f, 1f, 2f, 1f, 1f, 1f)
-        val result = array.dropLastWhile { it == 1f }
-        val expected = listOf(1f, 1f, 1f, 1f, 1f, 2f)
-
-        assertIterableEquals(expected, result)
-    }
-
-    @Test
-    fun givenList_whenDroppingMoreThanAvailable_thenThrowException() {
-        val list = listOf('a', 'e', 'i', 'o', 'u')
-        val result = list.drop(6)
-        val expected: List<String> = listOf()
-
-        assertIterableEquals(expected, result)
-    }
-
-}

core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/filter/FilterTest.kt

@@ -1,39 +0,0 @@
-package com.baeldung.filter
-
-import org.apache.commons.math3.primes.Primes
-import org.junit.jupiter.api.Assertions.assertIterableEquals
-import org.junit.jupiter.api.Test
-import kotlin.test.assertTrue
-
-internal class FilterTest {
-
-    @Test
-    fun givenAscendingValueMap_whenFilteringOnValue_ThenReturnSubsetOfMap() {
-        val originalMap = mapOf("key1" to 1, "key2" to 2, "key3" to 3)
-        val filteredMap = originalMap.filter { it.value < 2 }
-        val expectedMap = mapOf("key1" to 1)
-
-        assertTrue { expectedMap == filteredMap }
-    }
-
-    @Test
-    fun givenSeveralCollections_whenFilteringToAccumulativeList_thenListContainsAllContents() {
-        val array1 = arrayOf(90, 92, 93, 94, 92, 95, 93)
-        val array2 = sequenceOf(51, 31, 83, 674_506_111, 256_203_161, 15_485_863)
-        val list1 = listOf(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
-        val primes = mutableListOf<Int>()
-
-        val expected = listOf(2, 3, 5, 7, 31, 83, 15_485_863, 256_203_161, 674_506_111)
-
-        val primeCheck = { num: Int -> Primes.isPrime(num) }
-
-        array1.filterTo(primes, primeCheck)
-        list1.filterTo(primes, primeCheck)
-        array2.filterTo(primes, primeCheck)
-
-        primes.sort()
-
-        assertIterableEquals(expected, primes)
-    }
-
-}

core-kotlin-modules/core-kotlin-collections/src/test/kotlin/com/baeldung/filter/SliceTest.kt

@@ -1,45 +0,0 @@
-package com.baeldung.filter
-
-import org.junit.jupiter.api.Assertions.assertIterableEquals
-import org.junit.jupiter.api.Assertions.assertThrows
-import org.junit.jupiter.api.Test
-
-internal class SliceTest {
-
-    @Test
-    fun whenSlicingAnArrayWithDotRange_ThenListEqualsTheSlice() {
-        val original = arrayOf(1, 2, 3, 2, 1)
-        val actual = original.slice(1..3)
-        val expected = listOf(2, 3, 2)
-
-        assertIterableEquals(expected, actual)
-    }
-
-    @Test
-    fun whenSlicingAnArrayWithDownToRange_thenListMadeUpOfReverseSlice() {
-        val original = arrayOf(1, 2, 3, 2, 1)
-        val actual = original.slice(3 downTo 0)
-        val expected = listOf(2, 3, 2, 1)
-
-        assertIterableEquals(expected, actual)
-    }
-
-// From the 1.3 version of Kotlin APIs, slice doesn't return array of nulls but throw IndexOutOfBoundsException
-//    @Test
-//    fun whenSlicingBeyondTheRangeOfTheArray_thenContainManyNulls() {
-//        val original = arrayOf(12, 3, 34, 4)
-//        val actual = original.slice(3..8)
-//        val expected = listOf(4, null, null, null, null, null)
-//
-//        assertIterableEquals(expected, actual)
-//    }
-
-    @Test
-    fun whenSlicingBeyondRangeOfArrayWithStep_thenOutOfBoundsException() {
-        assertThrows(ArrayIndexOutOfBoundsException::class.java) {
-            val original = arrayOf(12, 3, 34, 4)
-            original.slice(3..8 step 2)
-        }
-    }
-
-}