Merge remote-tracking branch 'eugenp/master'

algorithms/README.md

@@ -28,3 +28,6 @@
 - [Calculate the Distance Between Two Points in Java](https://www.baeldung.com/java-distance-between-two-points)
 - [Find the Intersection of Two Lines in Java](https://www.baeldung.com/java-intersection-of-two-lines)
 - [Check If a String Contains All The Letters of The Alphabet](https://www.baeldung.com/java-string-contains-all-letters)
+- [Round Up to the Nearest Hundred](https://www.baeldung.com/java-round-up-nearest-hundred)
+- [Merge Sort in Java](https://www.baeldung.com/java-merge-sort)
+- [Calculate Percentage in Java](https://www.baeldung.com/java-calculate-percentage)

algorithms/pom.xml

@@ -17,6 +17,11 @@
             <artifactId>commons-math3</artifactId>
             <version>${commons-math3.version}</version>
         </dependency>
+        <dependency>
+            <groupId>commons-codec</groupId>
+            <artifactId>commons-codec</artifactId>
+            <version>${commons-codec.version}</version>
+        </dependency>
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
@@ -85,6 +90,7 @@
         <io.jenetics.version>3.7.0</io.jenetics.version>
         <org.jgrapht.core.version>1.0.1</org.jgrapht.core.version>
         <org.assertj.core.version>3.9.0</org.assertj.core.version>
+        <commons-codec.version>1.11</commons-codec.version>
     </properties>
 
 </project>

algorithms/src/main/java/com/baeldung/algorithms/conversion/HexStringConverter.java

@@ -0,0 +1,110 @@
+package com.baeldung.algorithms.conversion;
+
+import java.math.BigInteger;
+
+import javax.xml.bind.DatatypeConverter;
+
+import org.apache.commons.codec.DecoderException;
+import org.apache.commons.codec.binary.Hex;
+
+import com.google.common.io.BaseEncoding;
+
+public class HexStringConverter {
+
+    /**
+     * Create a byte Array from String of hexadecimal digits using Character conversion 
+     * @param hexString - Hexadecimal digits as String
+     * @return Desired byte Array
+     */
+    public byte[] decodeHexString(String hexString) {
+        if (hexString.length() % 2 == 1) {
+            throw new IllegalArgumentException("Invalid hexadecimal String supplied.");
+        }
+        byte[] bytes = new byte[hexString.length() / 2];
+
+        for (int i = 0; i < hexString.length(); i += 2) {
+            bytes[i / 2] = hexToByte(hexString.substring(i, i + 2));
+        }
+        return bytes;
+    }
+
+    /**
+     * Create a String of hexadecimal digits from a byte Array using Character conversion
+     * @param byteArray - The byte Array
+     * @return Desired String of hexadecimal digits in lower case
+     */
+    public String encodeHexString(byte[] byteArray) {
+        StringBuffer hexStringBuffer = new StringBuffer();
+        for (int i = 0; i < byteArray.length; i++) {
+            hexStringBuffer.append(byteToHex(byteArray[i]));
+        }
+        return hexStringBuffer.toString();
+    }
+
+    public String byteToHex(byte num) {
+        char[] hexDigits = new char[2];
+        hexDigits[0] = Character.forDigit((num >> 4) & 0xF, 16);
+        hexDigits[1] = Character.forDigit((num & 0xF), 16);
+        return new String(hexDigits);
+    }
+
+    public byte hexToByte(String hexString) {
+        int firstDigit = toDigit(hexString.charAt(0));
+        int secondDigit = toDigit(hexString.charAt(1));
+        return (byte) ((firstDigit << 4) + secondDigit);
+    }
+
+    private int toDigit(char hexChar) {
+        int digit = Character.digit(hexChar, 16);
+        if(digit == -1) {
+            throw new IllegalArgumentException("Invalid Hexadecimal Character: "+ hexChar);
+        }
+        return digit;
+    }
+
+    public String encodeUsingBigIntegerToString(byte[] bytes) {
+        BigInteger bigInteger = new BigInteger(1, bytes);
+        return bigInteger.toString(16);
+    }
+
+    public String encodeUsingBigIntegerStringFormat(byte[] bytes) {
+        BigInteger bigInteger = new BigInteger(1, bytes);
+        return String.format("%0" + (bytes.length << 1) + "x", bigInteger);
+    }
+
+    public byte[] decodeUsingBigInteger(String hexString) {
+        byte[] byteArray = new BigInteger(hexString, 16).toByteArray();
+        if (byteArray[0] == 0) {
+            byte[] output = new byte[byteArray.length - 1];
+            System.arraycopy(byteArray, 1, output, 0, output.length);
+            return output;
+        }
+        return byteArray;
+    }
+
+    public String encodeUsingDataTypeConverter(byte[] bytes) {
+        return DatatypeConverter.printHexBinary(bytes);
+    }
+
+    public byte[] decodeUsingDataTypeConverter(String hexString) {
+        return DatatypeConverter.parseHexBinary(hexString);
+    }
+
+    public String encodeUsingApacheCommons(byte[] bytes) throws DecoderException {
+        return Hex.encodeHexString(bytes);
+    }
+
+    public byte[] decodeUsingApacheCommons(String hexString) throws DecoderException {
+        return Hex.decodeHex(hexString);
+    }
+
+    public String encodeUsingGuava(byte[] bytes) {
+        return BaseEncoding.base16()
+            .encode(bytes);
+    }
+
+    public byte[] decodeUsingGuava(String hexString) {
+        return BaseEncoding.base16()
+            .decode(hexString.toUpperCase());
+    }
+}

algorithms/src/test/java/com/baeldung/algorithms/conversion/ByteArrayConverterUnitTest.java

@@ -0,0 +1,127 @@
+package com.baeldung.algorithms.conversion;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+
+import org.apache.commons.codec.DecoderException;
+import org.hamcrest.text.IsEqualIgnoringCase;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.baeldung.algorithms.conversion.HexStringConverter;
+
+public class ByteArrayConverterUnitTest {
+
+    private HexStringConverter hexStringConverter;
+
+    @Before
+    public void setup() {
+        hexStringConverter = new HexStringConverter();
+    }
+
+    @Test
+    public void shouldEncodeByteArrayToHexStringUsingBigIntegerToString() {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        if(hexString.charAt(0) == '0') {
+            hexString = hexString.substring(1);
+        }
+        String output = hexStringConverter.encodeUsingBigIntegerToString(bytes);
+        assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
+    }
+
+    @Test
+    public void shouldEncodeByteArrayToHexStringUsingBigIntegerStringFormat() {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        String output = hexStringConverter.encodeUsingBigIntegerStringFormat(bytes);
+        assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
+    }
+
+    @Test
+    public void shouldDecodeHexStringToByteArrayUsingBigInteger() {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        byte[] output = hexStringConverter.decodeUsingBigInteger(hexString);
+        assertArrayEquals(bytes, output);
+    }
+    
+    @Test
+    public void shouldEncodeByteArrayToHexStringUsingCharacterConversion() {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        String output = hexStringConverter.encodeHexString(bytes);
+        assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
+    }
+
+    @Test
+    public void shouldDecodeHexStringToByteArrayUsingCharacterConversion() {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        byte[] output = hexStringConverter.decodeHexString(hexString);
+        assertArrayEquals(bytes, output);
+    }
+    
+    @Test(expected=IllegalArgumentException.class)
+    public void shouldDecodeHexToByteWithInvalidHexCharacter() {
+        hexStringConverter.hexToByte("fg");
+    }
+
+    @Test
+    public void shouldEncodeByteArrayToHexStringDataTypeConverter() {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        String output = hexStringConverter.encodeUsingDataTypeConverter(bytes);
+        assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
+    }
+
+    @Test
+    public void shouldDecodeHexStringToByteArrayUsingDataTypeConverter() {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        byte[] output = hexStringConverter.decodeUsingDataTypeConverter(hexString);
+        assertArrayEquals(bytes, output);
+    }
+
+    @Test
+    public void shouldEncodeByteArrayToHexStringUsingGuava() {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        String output = hexStringConverter.encodeUsingGuava(bytes);
+        assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
+    }
+
+    @Test
+    public void shouldDecodeHexStringToByteArrayUsingGuava() {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        byte[] output = hexStringConverter.decodeUsingGuava(hexString);
+        assertArrayEquals(bytes, output);
+    }
+
+    @Test
+    public void shouldEncodeByteArrayToHexStringUsingApacheCommons() throws DecoderException {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        String output = hexStringConverter.encodeUsingApacheCommons(bytes);
+        assertThat(output, IsEqualIgnoringCase.equalToIgnoringCase(hexString));
+    }
+
+    @Test
+    public void shouldDecodeHexStringToByteArrayUsingApacheCommons() throws DecoderException {
+        byte[] bytes = getSampleBytes();
+        String hexString = getSampleHexString();
+        byte[] output = hexStringConverter.decodeUsingApacheCommons(hexString);
+        assertArrayEquals(bytes, output);
+    }
+
+    private String getSampleHexString() {
+        return "0af50c0e2d10";
+    }
+
+    private byte[] getSampleBytes() {
+        return new byte[] { 10, -11, 12, 14, 45, 16 };
+    }
+
+}

aws/README.md

@@ -9,4 +9,4 @@
 - [Integration Testing with a Local DynamoDB Instance](http://www.baeldung.com/dynamodb-local-integration-tests)
 - [Using the JetS3t Java Client With Amazon S3](http://www.baeldung.com/jets3t-amazon-s3)
 - [Managing Amazon SQS Queues in Java](http://www.baeldung.com/aws-queues-java)
-
+- [Guide to AWS Aurora RDS with Java](https://www.baeldung.com/aws-aurora-rds-java)

core-java-8/findItemsBasedOnValues/.gitignore

@@ -0,0 +1 @@
+/bin/

core-java-8/findItemsBasedOnValues/src/findItems/FindItemsBasedOnValues.java

@@ -0,0 +1,93 @@
+package findItems;
+
+import static org.junit.Assert.assertEquals;
+
+import java.text.ParseException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.junit.Test;
+
+public class FindItemsBasedOnValues {
+
+    List<Employee> EmplList = new ArrayList<Employee>();
+    List<Department> deptList = new ArrayList<Department>();
+
+    public static void main(String[] args) throws ParseException {
+        FindItemsBasedOnValues findItems = new FindItemsBasedOnValues();
+        findItems.givenDepartmentList_thenEmployeeListIsFilteredCorrectly();
+    }
+
+    @Test
+    public void givenDepartmentList_thenEmployeeListIsFilteredCorrectly() {
+        Integer expectedId = 1002;
+
+        populate(EmplList, deptList);
+
+        List<Employee> filteredList = EmplList.stream()
+            .filter(empl -> deptList.stream()
+                .anyMatch(dept -> dept.getDepartment()
+                    .equals("sales") && empl.getEmployeeId()
+                    .equals(dept.getEmployeeId())))
+            .collect(Collectors.toList());
+
+        assertEquals(expectedId, filteredList.get(0)
+            .getEmployeeId());
+    }
+
+    private void populate(List<Employee> EmplList, List<Department> deptList) {
+        Employee employee1 = new Employee(1001, "empl1");
+        Employee employee2 = new Employee(1002, "empl2");
+        Employee employee3 = new Employee(1003, "empl3");
+
+        Collections.addAll(EmplList, employee1, employee2, employee3);
+
+        Department department1 = new Department(1002, "sales");
+        Department department2 = new Department(1003, "marketing");
+        Department department3 = new Department(1004, "sales");
+
+        Collections.addAll(deptList, department1, department2, department3);
+    }
+}
+
+class Employee {
+    Integer employeeId;
+    String employeeName;
+
+    public Employee(Integer employeeId, String employeeName) {
+        super();
+        this.employeeId = employeeId;
+        this.employeeName = employeeName;
+    }
+
+    public Integer getEmployeeId() {
+        return employeeId;
+    }
+
+    public String getEmployeeName() {
+        return employeeName;
+    }
+
+}
+
+class Department {
+    Integer employeeId;
+    String department;
+
+    public Department(Integer employeeId, String department) {
+        super();
+        this.employeeId = employeeId;
+        this.department = department;
+    }
+
+    public Integer getEmployeeId() {
+        return employeeId;
+    }
+
+    public String getDepartment() {
+        return department;
+    }
+
+}

core-java-9/README.md

@@ -26,3 +26,4 @@
 - [Iterate Through a Range of Dates in Java](https://www.baeldung.com/java-iterate-date-range)
 - [Initialize a HashMap in Java](https://www.baeldung.com/java-initialize-hashmap)
 - [Java 9 Platform Logging API](https://www.baeldung.com/java-9-logging-api)
+- [Guide to java.lang.Process API](https://www.baeldung.com/java-process-api)

core-java-collections/README.md

@@ -52,3 +52,6 @@
 - [Performance of contains() in a HashSet vs ArrayList](https://www.baeldung.com/java-hashset-arraylist-contains-performance)
 - [Get the Key for a Value from a Java Map](https://www.baeldung.com/java-map-key-from-value)
 - [Time Complexity of Java Collections](https://www.baeldung.com/java-collections-complexity)
+- [Sort a HashMap in Java](https://www.baeldung.com/java-hashmap-sort)
+- [Finding the Highest Value in a Java Map](https://www.baeldung.com/java-find-map-max)
+- [Operating on and Removing an Item from Stream](https://www.baeldung.com/java-use-remove-item-stream)

core-java-collections/src/main/java/com/baeldung/enumset/EnumSets.java

@@ -0,0 +1,45 @@
+package com.baeldung.enumset;
+
+import java.util.ArrayList;
+import java.util.EnumSet;
+import java.util.List;
+
+public class EnumSets {
+
+    public enum Color {
+        RED, YELLOW, GREEN, BLUE, BLACK, WHITE
+    }
+
+    public static void main(String[] args) {
+        EnumSet<Color> allColors = EnumSet.allOf(Color.class);
+        System.out.println(allColors);
+
+        EnumSet<Color> noColors = EnumSet.noneOf(Color.class);
+        System.out.println(noColors);
+
+        EnumSet<Color> blackAndWhite = EnumSet.of(Color.BLACK, Color.WHITE);
+        System.out.println(blackAndWhite);
+
+        EnumSet<Color> noBlackOrWhite = EnumSet.complementOf(blackAndWhite);
+        System.out.println(noBlackOrWhite);
+
+        EnumSet<Color> range = EnumSet.range(Color.YELLOW, Color.BLUE);
+        System.out.println(range);
+
+        EnumSet<Color> blackAndWhiteCopy = EnumSet.copyOf(EnumSet.of(Color.BLACK, Color.WHITE));
+        System.out.println(blackAndWhiteCopy);
+
+        List<Color> colorsList = new ArrayList<>();
+        colorsList.add(Color.RED);
+        EnumSet<Color> listCopy = EnumSet.copyOf(colorsList);
+        System.out.println(listCopy);
+
+        EnumSet<Color> set = EnumSet.noneOf(Color.class);
+        set.add(Color.RED);
+        set.add(Color.YELLOW);
+        set.contains(Color.RED);
+        set.forEach(System.out::println);
+        set.remove(Color.RED);
+    }
+
+}

core-java-concurrency/README.md

@@ -29,3 +29,4 @@
 - [A Custom Spring SecurityConfigurer](http://www.baeldung.com/spring-security-custom-configurer)
 - [Life Cycle of a Thread in Java](http://www.baeldung.com/java-thread-lifecycle)
 - [Runnable vs. Callable in Java](http://www.baeldung.com/java-runnable-callable)
+- [Brief Introduction to Java Thread.yield()](https://www.baeldung.com/java-thread-yield)

core-java-concurrency/src/test/java/com/baeldung/completablefuture/CompletableFutureLongRunningUnitTest.java

@@ -184,5 +184,25 @@ public class CompletableFutureLongRunningUnitTest {
 
         assertEquals("Hello World", future.get());
     }
+    
+    @Test
+    public void whenPassingTransformation_thenFunctionExecutionWithThenApply() throws InterruptedException, ExecutionException {
+        CompletableFuture<Integer> finalResult = compute().thenApply(s -> s + 1);
+        assertTrue(finalResult.get() == 11);
+    }
+    
+    @Test
+    public void whenPassingPreviousStage_thenFunctionExecutionWithThenCompose() throws InterruptedException, ExecutionException {
+        CompletableFuture<Integer> finalResult = compute().thenCompose(this::computeAnother);
+        assertTrue(finalResult.get() == 20);
+    }
+    
+    public CompletableFuture<Integer> compute(){
+        return CompletableFuture.supplyAsync(() -> 10);
+    }
+    
+    public CompletableFuture<Integer> computeAnother(Integer i){
+        return CompletableFuture.supplyAsync(() -> 10 + i);
+    }
 
 }

core-java-io/src/main/resources/zipTest/test1.txt

@@ -0,0 +1 @@
+Test1

core-java-io/src/main/resources/zipTest/test2.txt

@@ -0,0 +1 @@
+Test2

core-java/README.md

@@ -150,3 +150,9 @@
 - [Throw Exception in Optional in Java 8](https://www.baeldung.com/java-optional-throw-exception)
 - [Add a Character to a String at a Given Position](https://www.baeldung.com/java-add-character-to-string)
 - [Synthetic Constructs in Java](https://www.baeldung.com/java-synthetic)
+- [Convert Double to String, Removing Decimal Places](https://www.baeldung.com/java-double-to-string)
+- [Different Ways to Capture Java Heap Dumps](https://www.baeldung.com/java-heap-dump-capture)
+- [How to Separate Double into Integer and Decimal Parts](https://www.baeldung.com/java-separate-double-into-integer-decimal-parts)
+- [ZoneOffset in Java](https://www.baeldung.com/java-zone-offset)
+- [Hashing a Password in Java](https://www.baeldung.com/java-password-hashing)
+- [Java Switch Statement](https://www.baeldung.com/java-switch)

core-java/src/main/java/com/baeldung/heapsort/Heap.java

@@ -0,0 +1,136 @@
+package com.baeldung.heapsort;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+public class Heap<E extends Comparable<E>> {
+
+    private List<E> elements = new ArrayList<>();
+
+    public static <E extends Comparable<E>> List<E> sort(Iterable<E> elements) {
+        Heap<E> heap = of(elements);
+
+        List<E> result = new ArrayList<>();
+
+        while (!heap.isEmpty()) {
+            result.add(heap.pop());
+        }
+
+        return result;
+    }
+
+    public static <E extends Comparable<E>> Heap<E> of(E... elements) {
+        return of(Arrays.asList(elements));
+    }
+
+    public static <E extends Comparable<E>> Heap<E> of(Iterable<E> elements) {
+        Heap<E> result = new Heap<>();
+        for (E element : elements) {
+            result.add(element);
+        }
+        return result;
+    }
+
+    public void add(E e) {
+        elements.add(e);
+        int elementIndex = elements.size() - 1;
+        while (!isRoot(elementIndex) && !isCorrectChild(elementIndex)) {
+            int parentIndex = parentIndex(elementIndex);
+            swap(elementIndex, parentIndex);
+            elementIndex = parentIndex;
+        }
+    }
+
+    public E pop() {
+        if (isEmpty()) {
+            throw new IllegalStateException("You cannot pop from an empty heap");
+        }
+
+        E result = elementAt(0);
+
+        int lasElementIndex = elements.size() - 1;
+        swap(0, lasElementIndex);
+        elements.remove(lasElementIndex);
+
+        int elementIndex = 0;
+        while (!isLeaf(elementIndex) && !isCorrectParent(elementIndex)) {
+            int smallerChildIndex = smallerChildIndex(elementIndex);
+            swap(elementIndex, smallerChildIndex);
+            elementIndex = smallerChildIndex;
+        }
+
+        return result;
+    }
+
+    public boolean isEmpty() {
+        return elements.isEmpty();
+    }
+    
+    private boolean isRoot(int index) {
+        return index == 0;
+    }
+
+    private int smallerChildIndex(int index) {
+        int leftChildIndex = leftChildIndex(index);
+        int rightChildIndex = rightChildIndex(index);
+        
+        if (!isValidIndex(rightChildIndex)) {
+            return leftChildIndex;
+        }
+
+        if (elementAt(leftChildIndex).compareTo(elementAt(rightChildIndex)) < 0) {
+            return leftChildIndex;
+        }
+
+        return rightChildIndex;
+    }
+
+    private boolean isLeaf(int index) {
+        return !isValidIndex(leftChildIndex(index));
+    }
+
+    private boolean isCorrectParent(int index) {
+        return isCorrect(index, leftChildIndex(index)) && isCorrect(index, rightChildIndex(index));
+    }
+
+    private boolean isCorrectChild(int index) {
+        return isCorrect(parentIndex(index), index);
+    }
+
+    private boolean isCorrect(int parentIndex, int childIndex) {
+        if (!isValidIndex(parentIndex) || !isValidIndex(childIndex)) {
+            return true;
+        }
+
+        return elementAt(parentIndex).compareTo(elementAt(childIndex)) < 0;
+    }
+
+    private boolean isValidIndex(int index) {
+        return index < elements.size();
+    }
+
+    private void swap(int index1, int index2) {
+        E element1 = elementAt(index1);
+        E element2 = elementAt(index2);
+        elements.set(index1, element2);
+        elements.set(index2, element1);
+    }
+
+    private E elementAt(int index) {
+        return elements.get(index);
+    }
+
+    private int parentIndex(int index) {
+        return (index - 1) / 2;
+    }
+
+    private int leftChildIndex(int index) {
+        return 2 * index + 1;
+    }
+
+    private int rightChildIndex(int index) {
+        return 2 * index + 2;
+    }
+
+}

core-java/src/test/java/com/baeldung/heapsort/HeapUnitTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.heapsort;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.Test;
+
+public class HeapUnitTest {
+
+    @Test
+    public void givenNotEmptyHeap_whenPopCalled_thenItShouldReturnSmallestElement() {
+        // given
+        Heap<Integer> heap = Heap.of(3, 5, 1, 4, 2);
+
+        // when
+        int head = heap.pop();
+
+        // then
+        assertThat(head).isEqualTo(1);
+    }
+    
+    @Test
+    public void givenNotEmptyIterable_whenSortCalled_thenItShouldReturnElementsInSortedList() {
+        // given
+        List<Integer> elements = Arrays.asList(3, 5, 1, 4, 2);
+        
+        // when
+        List<Integer> sortedElements = Heap.sort(elements);
+        
+        // then
+        assertThat(sortedElements).isEqualTo(Arrays.asList(1, 2, 3, 4, 5));
+    }
+
+}

core-kotlin/README.md

@@ -37,3 +37,5 @@
 - [Kotlin with Ktor](https://www.baeldung.com/kotlin-ktor)
 - [Fuel HTTP Library with Kotlin](https://www.baeldung.com/kotlin-fuel)
 - [Introduction to Kovenant Library for Kotlin](https://www.baeldung.com/kotlin-kovenant)
+- [Converting Kotlin Data Class from JSON using GSON](https://www.baeldung.com/kotlin-json-convert-data-class)
+- [Concatenate Strings in Kotlin](https://www.baeldung.com/kotlin-concatenate-strings)

gradle/junit5/build.gradle

@@ -0,0 +1,25 @@
+plugins {
+    // Apply the java-library plugin to add support for Java Library
+    id 'java-library'
+}
+
+dependencies {
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.3.1'
+    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.3.1'
+    
+    // Only necessary for JUnit 3 and 4 tests
+    testCompileOnly 'junit:junit:4.12' 
+    testRuntimeOnly 'org.junit.vintage:junit-vintage-engine:5.3.1' 
+    
+}
+
+repositories {
+    jcenter()
+}
+
+test {
+    useJUnitPlatform {
+    	includeTags 'fast'
+        excludeTags 'slow'
+    }
+}

gradle/junit5/src/test/java/com/example/CalculatorJUnit4Test.java

@@ -0,0 +1,12 @@
+package com.example;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+public class CalculatorJUnit4Test {
+    @Test
+    public void testAdd() {
+        assertEquals(42, Integer.sum(19, 23));
+    }
+}

gradle/junit5/src/test/java/com/example/CalculatorJUnit5Test.java

@@ -0,0 +1,36 @@
+package com.example;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;;
+
+public class CalculatorJUnit5Test {
+
+    @Tag("fast")
+    @Test
+    public void testAdd() {
+        assertEquals(42, Integer.sum(19, 23));
+    }
+
+    @Tag("slow")
+    @Test
+    public void testAddMaxInteger() {
+        assertEquals(2147483646, Integer.sum(2147183646, 300000));
+    }
+
+    @Tag("fast")
+    @Test
+    public void testAddZero() {
+        assertEquals(21, Integer.sum(21, 0));
+    }
+
+    @Tag("fast")
+    @Test
+    public void testDivide() {
+        assertThrows(ArithmeticException.class, () -> {
+            Integer.divideUnsigned(42, 0);
+        });
+    }
+}

gradle/settings.gradle

@@ -5,6 +5,6 @@ include 'greeting-library'
 include 'greeting-library-java'
 include 'greeter'
 include 'gradletaskdemo'
-
+include 'junit5'
 
 println 'This will be executed during the initialization phase.'

hibernate5/README.md

@@ -16,3 +16,4 @@
 - [Hibernate Entity Lifecycle](https://www.baeldung.com/hibernate-entity-lifecycle)
 - [Mapping A Hibernate Query to a Custom Class](https://www.baeldung.com/hibernate-query-to-custom-class)
 - [@JoinColumn Annotation Explained](https://www.baeldung.com/jpa-join-column)
+- [Hibernate 5 Naming Strategy Configuration](https://www.baeldung.com/hibernate-naming-strategy)

java-dates/src/test/java/com/baeldung/date/DateDiffUnitTest.java

@@ -51,6 +51,15 @@ public class DateDiffUnitTest {
         assertEquals(diff, 6);
     }
 
+    @Test
+    public void givenTwoZonedDateTimesInJava8_whenDifferentiating_thenWeGetSix() {
+        LocalDateTime ldt = LocalDateTime.now();
+        ZonedDateTime now = ldt.atZone(ZoneId.of("America/Montreal"));
+        ZonedDateTime sixDaysBehind = now.withZoneSameInstant(ZoneId.of("Asia/Singapore")).minusDays(6);
+        long diff = ChronoUnit.DAYS.between(sixDaysBehind, now);
+        assertEquals(diff, 6);
+    }
+
     @Test
     public void givenTwoDatesInJodaTime_whenDifferentiating_thenWeGetSix() {
         org.joda.time.LocalDate now = org.joda.time.LocalDate.now();

java-streams/README.md

@@ -13,3 +13,4 @@
 - [How to Iterate Over a Stream With Indices](http://www.baeldung.com/java-stream-indices)
 - [Primitive Type Streams in Java 8](http://www.baeldung.com/java-8-primitive-streams)
 - [Stream Ordering in Java](https://www.baeldung.com/java-stream-ordering)
+- [Introduction to Protonpack](https://www.baeldung.com/java-protonpack)

java-strings/README.md

@@ -31,3 +31,5 @@
 - [Converting a Stack Trace to a String in Java](https://www.baeldung.com/java-stacktrace-to-string)
 - [Sorting a String Alphabetically in Java](https://www.baeldung.com/java-sort-string-alphabetically)
 - [Remove Emojis from a Java String](https://www.baeldung.com/java-string-remove-emojis)
+- [String Not Empty Test Assertions in Java](https://www.baeldung.com/java-assert-string-not-empty)
+- [String Performance Hints](https://www.baeldung.com/java-string-performance)

javaxval/README.md

@@ -9,3 +9,4 @@ The "REST With Spring" Classes: http://bit.ly/restwithspring
 - [Java Bean Validation Basics](http://www.baeldung.com/javax-validation)
 - [Validating Container Elements with Bean Validation 2.0](http://www.baeldung.com/bean-validation-container-elements)
 - [Method Constraints with Bean Validation 2.0](http://www.baeldung.com/javax-validation-method-constraints)
+- [Difference Between @NotNull, @NotEmpty, and @NotBlank Constraints in Bean Validation](https://www.baeldung.com/java-bean-validation-not-null-empty-blank)

jersey/src/main/java/com/baeldung/jersey/server/model/Fruit.java

@@ -54,4 +54,9 @@ public class Fruit {
     public void setSerial(String serial) {
         this.serial = serial;
     }
+    
+    @Override
+    public String toString() {
+        return "Fruit [name: " + getName() + " colour: " + getColour() + "]";
+    }
 }

jersey/src/main/java/com/baeldung/jersey/server/rest/FruitResource.java

@@ -16,6 +16,8 @@ import javax.ws.rs.Path;
 import javax.ws.rs.PathParam;
 import javax.ws.rs.Produces;
 import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
+import javax.ws.rs.core.Response.Status;
 
 import org.glassfish.jersey.server.mvc.ErrorTemplate;
 import org.glassfish.jersey.server.mvc.Template;
@@ -86,6 +88,16 @@ public class FruitResource {
     public void createFruit(@Valid Fruit fruit) {
         SimpleStorageService.storeFruit(fruit);
     }
+    
+    @POST
+    @Path("/created")
+    @Consumes(MediaType.APPLICATION_JSON)
+    public Response createNewFruit(@Valid Fruit fruit) {
+        String result = "Fruit saved : " + fruit;
+        return Response.status(Status.CREATED.getStatusCode())
+            .entity(result)
+            .build();
+    }
 
     @GET
     @Valid

jersey/src/test/java/com/baeldung/jersey/server/GreetingsResourceIntegrationTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.jersey.server;
+
+import static org.junit.Assert.assertEquals;
+
+import javax.ws.rs.core.Application;
+import javax.ws.rs.core.HttpHeaders;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
+import javax.ws.rs.core.Response.Status;
+
+import org.glassfish.jersey.server.ResourceConfig;
+import org.glassfish.jersey.test.JerseyTest;
+import org.junit.Test;
+
+public class GreetingsResourceIntegrationTest extends JerseyTest {
+
+    @Override
+    protected Application configure() {
+        return new ResourceConfig(Greetings.class);
+    }
+
+    @Test
+    public void givenGetHiGreeting_whenCorrectRequest_thenResponseIsOkAndContainsHi() {
+        Response response = target("/greetings/hi").request()
+            .get();
+
+        assertEquals("Http Response should be 200: ", Status.OK.getStatusCode(), response.getStatus());
+        assertEquals("Http Content-Type should be: ", MediaType.TEXT_HTML, response.getHeaderString(HttpHeaders.CONTENT_TYPE));
+
+        String content = response.readEntity(String.class);
+        assertEquals("Content of ressponse is: ", "hi", content);
+    }
+}