Merge remote-tracking branch 'eugenp/master'

core-java-8/README.md

@@ -33,3 +33,4 @@
 - [Display All Time Zones With GMT And UTC in Java](http://www.baeldung.com/java-time-zones)
 - [Copy a File with Java](http://www.baeldung.com/java-copy-file)
 - [Generating Prime Numbers in Java](http://www.baeldung.com/java-generate-prime-numbers)
+- [Static and Default Methods in Interfaces in Java](http://www.baeldung.com/java-static-default-methods)

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

@@ -0,0 +1,18 @@
+package com.baeldung.defaultstaticinterfacemethods.application;
+
+import com.baeldung.defaultstaticinterfacemethods.model.Car;
+import com.baeldung.defaultstaticinterfacemethods.model.Vehicle;
+
+public class Application {
+
+    public static void main(String[] args) {
+
+        Vehicle car = new Car("BMW");
+        System.out.println(car.getBrand());
+        System.out.println(car.speedUp());
+        System.out.println(car.slowDown());
+        System.out.println(car.turnAlarmOn());
+        System.out.println(car.turnAlarmOff());
+        System.out.println(Vehicle.getHorsePower(2500, 480));
+    }
+}

core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/Alarm.java

@@ -0,0 +1,12 @@
+package com.baeldung.defaultstaticinterfacemethods.model;
+
+public interface Alarm {
+
+    default String turnAlarmOn() {
+        return "Turning the alarm on.";
+    }
+
+    default String turnAlarmOff() {
+        return "Turning the alarm off.";
+    }
+}

core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/Car.java

@@ -0,0 +1,25 @@
+package com.baeldung.defaultstaticinterfacemethods.model;
+
+public class Car implements Vehicle {
+
+    private final String brand;
+
+    public Car(String brand) {
+        this.brand = brand;
+    }
+
+    @Override
+    public String getBrand() {
+        return brand;
+    }
+
+    @Override
+    public String speedUp() {
+        return "The car is speeding up.";
+    }
+
+    @Override
+    public String slowDown() {
+        return "The car is slowing down.";
+    }
+}

core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/Motorbike.java

@@ -0,0 +1,25 @@
+package com.baeldung.defaultstaticinterfacemethods.model;
+
+public class Motorbike implements Vehicle {
+
+    private final String brand;
+
+    public Motorbike(String brand) {
+        this.brand = brand;
+    }
+
+    @Override
+    public String getBrand() {
+        return brand;
+    }
+
+    @Override
+    public String speedUp() {
+        return "The motorbike is speeding up.";
+    }
+
+    @Override
+    public String slowDown() {
+        return "The motorbike is slowing down.";
+    }
+}

core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/MultiAlarmCar.java

@@ -0,0 +1,35 @@
+package com.baeldung.defaultstaticinterfacemethods.model;
+
+public class MultiAlarmCar implements Vehicle, Alarm {
+
+    private final String brand;
+
+    public MultiAlarmCar(String brand) {
+        this.brand = brand;
+    }
+
+    @Override
+    public String getBrand() {
+        return brand;
+    }
+
+    @Override
+    public String speedUp() {
+        return "The motorbike is speeding up.";
+    }
+
+    @Override
+    public String slowDown() {
+        return "The mootorbike is slowing down.";
+    }
+
+    @Override
+    public String turnAlarmOn() {
+        return Vehicle.super.turnAlarmOn() + " " + Alarm.super.turnAlarmOn();
+    }
+
+    @Override
+    public String turnAlarmOff() {
+        return Vehicle.super.turnAlarmOff() + " " + Alarm.super.turnAlarmOff();
+    }
+}

core-java-8/src/main/java/com/baeldung/defaultstaticinterfacemethods/model/Vehicle.java

@@ -0,0 +1,22 @@
+package com.baeldung.defaultstaticinterfacemethods.model;
+
+public interface Vehicle {
+
+    String getBrand();
+
+    String speedUp();
+
+    String slowDown();
+
+    default String turnAlarmOn() {
+        return "Turning the vehice alarm on.";
+    }
+
+    default String turnAlarmOff() {
+        return "Turning the vehicle alarm off.";
+    }
+
+    static int getHorsePower(int rpm, int torque) {
+        return (rpm * torque) / 5252;
+    }
+}

core-java-8/src/main/java/com/baeldung/iterators/Iterators.java

@@ -0,0 +1,80 @@
+package com.baeldung.iterators;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Source code https://github.com/eugenp/tutorials
+ *
+ * @author Santosh Thakur
+ */
+
+public class Iterators {
+
+    public static int failFast1() {
+        ArrayList<Integer> numbers = new ArrayList<>();
+
+        numbers.add(10);
+        numbers.add(20);
+        numbers.add(30);
+        numbers.add(40);
+
+        Iterator<Integer> iterator = numbers.iterator();
+        while (iterator.hasNext()) {
+            Integer number = iterator.next();
+            numbers.add(50);
+        }
+
+        return numbers.size();
+    }
+
+    public static int failFast2() {
+        ArrayList<Integer> numbers = new ArrayList<>();
+        numbers.add(10);
+        numbers.add(20);
+        numbers.add(30);
+        numbers.add(40);
+
+        Iterator<Integer> iterator = numbers.iterator();
+        while (iterator.hasNext()) {
+            if (iterator.next() == 30) {
+                // will not throw Exception
+                iterator.remove();
+            }
+        }
+
+        System.out.println("using iterator's remove method = " + numbers);
+
+        iterator = numbers.iterator();
+        while (iterator.hasNext()) {
+            if (iterator.next() == 40) {
+                // will throw Exception on
+                // next call of next() method
+                numbers.remove(2);
+            }
+        }
+
+        return numbers.size();
+    }
+
+    public static int failSafe1() {
+        ConcurrentHashMap<String, Integer> map = new ConcurrentHashMap<>();
+
+        map.put("First", 10);
+        map.put("Second", 20);
+        map.put("Third", 30);
+        map.put("Fourth", 40);
+
+        Iterator<String> iterator = map.keySet()
+            .iterator();
+
+        while (iterator.hasNext()) {
+            String key = iterator.next();
+            map.put("Fifth", 50);
+        }
+
+        return map.size();
+    }
+
+}

core-java-8/src/test/java/com/baeldung/counter/CounterStatistics.java

@@ -2,6 +2,7 @@ package com.baeldung.counter;
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Random;
 
 import org.openjdk.jmh.annotations.Benchmark;
 import org.openjdk.jmh.annotations.BenchmarkMode;
@@ -18,8 +19,18 @@ public class CounterStatistics {
     private static final Map<String, MutableInteger> counterWithMutableIntMap = new HashMap<>();
     private static final Map<String, int[]> counterWithIntArrayMap = new HashMap<>();
     private static final Map<String, Long> counterWithLongWrapperMap = new HashMap<>();
+    private static final Map<String, Long> counterWithLongWrapperStreamMap = new HashMap<>();
+    
+    static {
+        CounterUtil.COUNTRY_NAMES = new String[10000];
+        final String prefix = "NewString"; 
+        Random random = new Random();
+        for (int i=0; i<10000; i++) {
+            CounterUtil.COUNTRY_NAMES[i] = new String(prefix + random.nextInt(1000));
+        }
+    }
 
-    @Benchmark
+  @Benchmark
     public void wrapperAsCounter() {
         CounterUtil.counterWithWrapperObject(counterMap);
     }
@@ -28,6 +39,11 @@ public class CounterStatistics {
     public void lambdaExpressionWithWrapper() {
         CounterUtil.counterWithLambdaAndWrapper(counterWithLongWrapperMap);
     }
+    
+    @Benchmark
+    public void parallelStreamWithWrapper() {
+        CounterUtil.counterWithParallelStreamAndWrapper(counterWithLongWrapperStreamMap);
+    }
 
     @Benchmark
     public void mutableIntegerAsCounter() {

core-java-8/src/test/java/com/baeldung/counter/CounterUtil.java

@@ -6,7 +6,7 @@ import java.util.stream.Stream;
 
 public class CounterUtil {
 
-    private final static String[] COUNTRY_NAMES = { "China", "Australia", "India", "USA", "USSR", "UK", "China", "France", "Poland", "Austria", "India", "USA", "Egypt", "China" };
+    public static String[] COUNTRY_NAMES = { "China", "Australia", "India", "USA", "USSR", "UK", "China", "France", "Poland", "Austria", "India", "USA", "Egypt", "China" };
 
     public static void counterWithWrapperObject(Map<String, Integer> counterMap) {
         for (String country : COUNTRY_NAMES) {
@@ -15,9 +15,14 @@ public class CounterUtil {
     }
 
     public static void counterWithLambdaAndWrapper(Map<String, Long> counterMap) {
-        counterMap.putAll(Stream.of(COUNTRY_NAMES)
+        Stream.of(COUNTRY_NAMES)
+            .collect(Collectors.groupingBy(k -> k, () -> counterMap, Collectors.counting()));
+    }
+
+    public static void counterWithParallelStreamAndWrapper(Map<String, Long> counterMap) {
+        Stream.of(COUNTRY_NAMES)
             .parallel()
-            .collect(Collectors.groupingBy(k -> k, Collectors.counting())));
+            .collect(Collectors.groupingBy(k -> k, () -> counterMap, Collectors.counting()));
     }
 
     public static class MutableInteger {
@@ -49,4 +54,4 @@ public class CounterUtil {
         }
     }
 
-}
+}

core-java-8/src/test/java/com/baeldung/defaultistaticinterfacemethods/test/StaticDefaulInterfaceMethodUnitTest.java

@@ -0,0 +1,79 @@
+package com.baeldung.defaultistaticinterfacemethods.test;
+
+import com.baeldung.defaultstaticinterfacemethods.model.Car;
+import com.baeldung.defaultstaticinterfacemethods.model.Motorbike;
+import com.baeldung.defaultstaticinterfacemethods.model.Vehicle;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.assertj.core.api.Assertions.*;
+
+public class StaticDefaulInterfaceMethodUnitTest {
+
+    private static Car car;
+    private static Motorbike motorbike;
+
+    @BeforeClass
+    public static void setUpCarInstance() {
+        car = new Car("BMW");
+    }
+
+    @BeforeClass
+    public static void setUpMotorbikeInstance() {
+        motorbike = new Motorbike("Yamaha");
+    }
+
+    @Test
+    public void givenCarInstace_whenBrandisBMW_thenOneAssertion() {
+        assertThat(car.getBrand()).isEqualTo("BMW");
+    }
+
+    @Test
+    public void givenCarInstance_whenCallingSpeedUp_thenOneAssertion() {
+        assertThat(car.speedUp()).isEqualTo("The car is speeding up.");
+    }
+
+    @Test
+    public void givenCarInstance_whenCallingSlowDown_thenOneAssertion() {
+        assertThat(car.slowDown()).isEqualTo("The car is slowing down.");
+    }
+
+    @Test
+    public void givenCarInstance_whenCallingTurnAlarmOn_thenOneAssertion() {
+        assertThat(car.turnAlarmOn()).isEqualTo("Turning the vehice alarm on.");
+    }
+
+    @Test
+    public void givenCarInstance_whenCallingTurnAlarmOff_thenOneAssertion() {
+        assertThat(car.turnAlarmOff()).isEqualTo("Turning the vehicle alarm off.");
+    }
+
+    @Test
+    public void givenVehicleInterface_whenCallinggetHorsePower_thenOneAssertion() {
+        assertThat(Vehicle.getHorsePower(2500, 480)).isEqualTo(228);
+    }
+
+    @Test
+    public void givenMooorbikeInstace_whenBrandisYamaha_thenOneAssertion() {
+        assertThat(motorbike.getBrand()).isEqualTo("Yamaha");
+    }
+
+    @Test
+    public void givenMotorbikeInstance_whenCallingSpeedUp_thenOneAssertion() {
+        assertThat(motorbike.speedUp()).isEqualTo("The motorbike is speeding up.");
+    }
+
+    @Test
+    public void givenMotorbikeInstance_whenCallingSlowDown_thenOneAssertion() {
+        assertThat(motorbike.slowDown()).isEqualTo("The motorbike is slowing down.");
+    }
+
+    @Test
+    public void givenMotorbikeInstance_whenCallingTurnAlarmOn_thenOneAssertion() {
+        assertThat(motorbike.turnAlarmOn()).isEqualTo("Turning the vehice alarm on.");
+    }
+
+    @Test
+    public void givenMotorbikeInstance_whenCallingTurnAlarmOff_thenOneAssertion() {
+        assertThat(motorbike.turnAlarmOff()).isEqualTo("Turning the vehicle alarm off.");
+    }
+}

core-java-8/src/test/java/com/baeldung/iterators/IteratorsTest.java

@@ -0,0 +1,40 @@
+package com.baeldung.iterators;
+
+import static com.baeldung.iterators.Iterators.failFast1;
+import static com.baeldung.iterators.Iterators.failFast2;
+import static com.baeldung.iterators.Iterators.failSafe1;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import java.util.ConcurrentModificationException;
+
+import org.junit.Test;
+
+/**
+ * Source code https://github.com/eugenp/tutorials
+ *
+ * @author Santosh Thakur
+ */
+
+public class IteratorsTest {
+
+    @Test
+    public void whenFailFast_ThenThrowsException() {
+        assertThatThrownBy(() -> {
+            failFast1();
+        }).isInstanceOf(ConcurrentModificationException.class);
+    }
+
+    @Test
+    public void whenFailFast_ThenThrowsExceptionInSecondIteration() {
+        assertThatThrownBy(() -> {
+            failFast2();
+        }).isInstanceOf(ConcurrentModificationException.class);
+    }
+
+    @Test
+    public void whenFailSafe_ThenDoesNotThrowException() {
+        assertThat(failSafe1()).isGreaterThanOrEqualTo(0);
+    }
+
+}

core-java-9/README.md

@@ -19,3 +19,4 @@
 - [Java 9 java.util.Objects Additions](http://www.baeldung.com/java-9-objects-new)
 - [Compact Strings in Java 9](http://www.baeldung.com/java-9-compact-string)
 - [Convert Date to LocalDate or LocalDateTime and Back](http://www.baeldung.com/java-date-to-localdate-and-localdatetime)
+- [Java 9 Variable Handles Demistyfied](http://www.baeldung.com/java-variable-handles)

core-java/README.md

@@ -127,3 +127,8 @@
 - [Introduction to the Java ArrayDeque](http://www.baeldung.com/java-array-deque)
 - [Guide to java.util.Formatter](http://www.baeldung.com/java-string-formatter)
 - [Batch Processing in JDBC](http://www.baeldung.com/jdbc-batch-processing)
+- [Check if a Java Array Contains a Value](http://www.baeldung.com/java-array-contains-value)
+- [How to Invert an Array in Java](http://www.baeldung.com/java-invert-array)
+- [Guide to the Cipher Class](http://www.baeldung.com/java-cipher-class)
+- [A Guide to Java Initialization](http://www.baeldung.com/java-initialization)
+

core-java/src/main/java/com/baeldung/cipher/Encryptor.java

@@ -0,0 +1,35 @@
+package com.baeldung.cipher;
+
+import javax.crypto.*;
+import javax.crypto.spec.SecretKeySpec;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+import java.security.cert.Certificate;
+
+public class Encryptor {
+
+    public byte[] encryptMessage(byte[] message, byte[] keyBytes) throws InvalidKeyException, NoSuchPaddingException, NoSuchAlgorithmException, BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
+        SecretKey secretKey = new SecretKeySpec(keyBytes, "AES");
+        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
+        byte[] encryptedMessage = cipher.doFinal(message);
+        return encryptedMessage;
+    }
+
+    public byte[] encryptMessage(byte[] message, Certificate publicKeyCertificate) throws InvalidKeyException, NoSuchPaddingException, NoSuchAlgorithmException, BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
+        cipher.init(Cipher.ENCRYPT_MODE, publicKeyCertificate);
+        byte[] encryptedMessage = cipher.doFinal(message);
+        return encryptedMessage;
+    }
+
+    public byte[] decryptMessage(byte[] encryptedMessage, byte[] keyBytes) throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException {
+        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
+        SecretKey secretKey = new SecretKeySpec(keyBytes, "AES");
+        cipher.init(Cipher.DECRYPT_MODE, secretKey);
+        byte[] clearMessage = cipher.doFinal(encryptedMessage);
+        return clearMessage;
+    }
+
+
+}

core-java/src/main/java/com/baeldung/initializationguide/User.java

@@ -0,0 +1,53 @@
+package com.baeldung.initializationguide;
+
+import java.io.Serializable;
+
+public class User implements Serializable, Cloneable {
+    private static final long serialVersionUID = 1L;
+    static String forum;
+    private String name;
+    private int id;
+
+    {
+        id = 0;
+        System.out.println("Instance Initializer");
+    }
+
+    static {
+    	forum = "Java";
+        System.out.println("Static Initializer");
+    }
+
+    public User(String name, int id) {
+        super();
+        this.name = name;
+        this.id = id;
+    }
+
+    public User() {
+        System.out.println("Constructor");
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    @Override
+    protected Object clone() throws CloneNotSupportedException {
+        return this;
+    }
+
+}
+

core-java/src/main/java/com/baeldung/tree/BinaryTree.java

@@ -8,15 +8,7 @@ public class BinaryTree {
     Node root;
 
     public void add(int value) {
-
-        Node newNode = new Node(value);
-
-        if (root == null) {
-            root = newNode;
-            return;
-        }
-
-        addRecursive(root, value);
+        root = addRecursive(root, value);
     }
 
     private Node addRecursive(Node current, int value) {
@@ -27,34 +19,41 @@ public class BinaryTree {
 
         if (value < current.value) {
             current.left = addRecursive(current.left, value);
-        } else {
+        } else if (value > current.value) {
             current.right = addRecursive(current.right, value);
         }
 
         return current;
-
     }
 
     public boolean isEmpty() {
         return root == null;
     }
 
+    public int getSize() {
+        return getSizeRecursive(root);
+    }
+
+    private int getSizeRecursive(Node current) {
+        return current == null ? 0 : getSizeRecursive(current.left) + 1 + getSizeRecursive(current.right);
+    }
+
     public boolean containsNode(int value) {
         return containsNodeRecursive(root, value);
     }
 
     private boolean containsNodeRecursive(Node current, int value) {
-
         if (current == null) {
             return false;
-        } else if (value == current.value) {
-            return true;
-        } else if (value < current.value) {
-            return containsNodeRecursive(current.left, value);
-        } else {
-            return containsNodeRecursive(current.right, value);
         }
 
+        if (value == current.value) {
+            return true;
+        }
+
+        return value < current.value
+          ? containsNodeRecursive(current.left, value)
+          : containsNodeRecursive(current.right, value);
     }
 
     public void delete(int value) {
@@ -86,23 +85,18 @@ public class BinaryTree {
             current.value = smallestValue;
             current.right = deleteRecursive(current.right, smallestValue);
             return current;
-
-        } else if (value < current.value) {
+        }
+        if (value < current.value) {
             current.left = deleteRecursive(current.left, value);
             return current;
-        } else {
-            current.right = deleteRecursive(current.right, value);
-            return current;
         }
+
+        current.right = deleteRecursive(current.right, value);
+        return current;
     }
 
     private int findSmallestValue(Node root) {
-
-        if (root.left == null) {
-            return root.value;
-        }
-
-        return findSmallestValue(root.left);
+        return root.left == null ? root.value : findSmallestValue(root.left);
     }
 
     public void traverseInOrder(Node node) {
@@ -125,12 +119,15 @@ public class BinaryTree {
         if (node != null) {
             traversePostOrder(node.left);
             traversePostOrder(node.right);
-
             System.out.print(" " + node.value);
         }
     }
 
     public void traverseLevelOrder() {
+        if (root == null) {
+            return;
+        }
+
         Queue<Node> nodes = new LinkedList<>();
         nodes.add(root);
 

core-java/src/test/java/com/baeldung/cipher/EncryptorUnitTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.cipher;
+
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
+import java.security.cert.CertificateFactory;
+import java.security.cert.X509Certificate;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class EncryptorUnitTest {
+    private String encKeyString;
+    private String message;
+    private String  certificateString;
+    private Encryptor encryptor;
+
+    @Before
+    public void init(){
+        encKeyString =  "1234567890123456";
+        message = "This is a secret message";
+        encryptor =  new Encryptor();
+        certificateString = "-----BEGIN CERTIFICATE-----\n" +
+                "MIICVjCCAb8CAg37MA0GCSqGSIb3DQEBBQUAMIGbMQswCQYDVQQGEwJKUDEOMAwG\n" +
+                "A1UECBMFVG9reW8xEDAOBgNVBAcTB0NodW8ta3UxETAPBgNVBAoTCEZyYW5rNERE\n" +
+                "MRgwFgYDVQQLEw9XZWJDZXJ0IFN1cHBvcnQxGDAWBgNVBAMTD0ZyYW5rNEREIFdl\n" +
+                "YiBDQTEjMCEGCSqGSIb3DQEJARYUc3VwcG9ydEBmcmFuazRkZC5jb20wHhcNMTIw\n" +
+                "ODIyMDUyNzIzWhcNMTcwODIxMDUyNzIzWjBKMQswCQYDVQQGEwJKUDEOMAwGA1UE\n" +
+                "CAwFVG9reW8xETAPBgNVBAoMCEZyYW5rNEREMRgwFgYDVQQDDA93d3cuZXhhbXBs\n" +
+                "ZS5jb20wgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBAMYBBrx5PlP0WNI/ZdzD\n" +
+                "+6Pktmurn+F2kQYbtc7XQh8/LTBvCo+P6iZoLEmUA9e7EXLRxgU1CVqeAi7QcAn9\n" +
+                "MwBlc8ksFJHB0rtf9pmf8Oza9E0Bynlq/4/Kb1x+d+AyhL7oK9tQwB24uHOueHi1\n" +
+                "C/iVv8CSWKiYe6hzN1txYe8rAgMBAAEwDQYJKoZIhvcNAQEFBQADgYEAASPdjigJ\n" +
+                "kXCqKWpnZ/Oc75EUcMi6HztaW8abUMlYXPIgkV2F7YanHOB7K4f7OOLjiz8DTPFf\n" +
+                "jC9UeuErhaA/zzWi8ewMTFZW/WshOrm3fNvcMrMLKtH534JKvcdMg6qIdjTFINIr\n" +
+                "evnAhf0cwULaebn+lMs8Pdl7y37+sfluVok=\n" +
+                "-----END CERTIFICATE-----";
+    }
+
+    @Test
+    public void givenEncryptionKey_whenMessageIsPassedToEncryptor_thenMessageIsEncrypted() throws Exception {
+        byte[] encryptedMessage = encryptor.encryptMessage(message.getBytes(),encKeyString.getBytes());
+
+        assertThat(encryptedMessage).isNotNull();
+        assertThat(encryptedMessage.length  % 32).isEqualTo(0);
+    }
+
+    @Test
+    public void givenCertificateWithPublicKey_whenMessageIsPassedToEncryptor_thenMessageIsEncrypted() throws Exception {
+        CertificateFactory factory = CertificateFactory.getInstance("X.509");
+        InputStream is = new ByteArrayInputStream(certificateString.getBytes());
+        X509Certificate certificate = (X509Certificate) factory.generateCertificate(is);
+
+        byte[] encryptedMessage = encryptor.encryptMessage(message.getBytes(),certificate);
+
+        assertThat(encryptedMessage).isNotNull();
+        assertThat(encryptedMessage.length  % 128).isEqualTo(0);
+    }
+
+    @Test
+    public void givenEncryptionKey_whenMessageIsEncrypted_thenDecryptMessage() throws Exception{
+        byte[] encryptedMessageBytes = encryptor.encryptMessage(message.getBytes(),encKeyString.getBytes());
+
+        byte[] clearMessageBytes = encryptor.decryptMessage(encryptedMessageBytes, encKeyString.getBytes());
+
+        assertThat(message).isEqualTo(new String(clearMessageBytes));
+    }
+}

core-java/src/test/java/com/baeldung/initializationguide/UserTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.initializationguide;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.*;
+
+import java.lang.reflect.InvocationTargetException;
+
+public class UserTest {
+
+    @Test
+    public void givenUserInstance_whenIntializedWithNew_thenInstanceIsNotNull() {
+        User user = new User("Alice", 1);
+        assertThat(user).isNotNull();
+    }
+
+    @Test
+    public void givenUserInstance_whenInitializedWithReflection_thenInstanceIsNotNull() throws InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException, NoSuchMethodException, SecurityException {
+        User user = User.class.getConstructor(String.class, int.class)
+            .newInstance("Alice", 2);
+        assertThat(user).isNotNull();
+    }
+
+    @Test
+    public void givenUserInstance_whenCopiedWithClone_thenExactMatchIsCreated() throws CloneNotSupportedException {
+        User user = new User("Alice", 3);
+        User clonedUser = (User) user.clone();
+        assertThat(clonedUser).isEqualTo(user);
+    }
+
+    @Test
+    public void givenUserInstance_whenValuesAreNotInitialized_thenUserNameAndIdReturnDefault() {
+        User user = new User();
+        assertThat(user.getName()).isNull();
+        assertThat(user.getId() == 0);
+    }
+}

core-java/src/test/java/com/baeldung/tree/BinaryTreeTest.java

@@ -1,5 +1,6 @@
 package com.baeldung.tree;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
@@ -26,6 +27,26 @@ public class BinaryTreeTest {
         assertFalse(bt.containsNode(1));
     }
 
+    @Test
+    public void givenABinaryTree_WhenAddingExistingElement_ThenElementIsNotAdded() {
+
+        BinaryTree bt = createBinaryTree();
+
+        int initialSize = bt.getSize();
+
+        assertTrue(bt.containsNode(3));
+        bt.add(3);
+        assertEquals(initialSize, bt.getSize());
+    }
+
+    @Test
+    public void givenABinaryTree_WhenLookingForNonExistingElement_ThenReturnsFalse() {
+
+        BinaryTree bt = createBinaryTree();
+
+        assertFalse(bt.containsNode(99));
+    }
+
     @Test
     public void givenABinaryTree_WhenDeletingElements_ThenTreeDoesNotContainThoseElements() {
 
@@ -36,6 +57,19 @@ public class BinaryTreeTest {
         assertFalse(bt.containsNode(9));
     }
 
+    @Test
+    public void givenABinaryTree_WhenDeletingNonExistingElement_ThenTreeDoesNotDelete() {
+
+        BinaryTree bt = createBinaryTree();
+
+        int initialSize = bt.getSize();
+
+        assertFalse(bt.containsNode(99));
+        bt.delete(99);
+        assertFalse(bt.containsNode(99));
+        assertEquals(initialSize, bt.getSize());
+    }
+
     @Test
     public void givenABinaryTree_WhenTraversingInOrder_ThenPrintValues() {
 

flyway/flyway-callbacks/pom.xml

@@ -1,59 +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>flyway-callbacks</artifactId>
-	<version>0.0.1-SNAPSHOT</version>
-	<packaging>jar</packaging>
-
-	<name>flyway-callbacks</name>
-	<description>Flyway Callbacks Demo</description>
-
-	<parent>
-		<artifactId>flyway</artifactId>
-		<groupId>com.baeldung</groupId>
-		<version>1.0</version>
-		<relativePath>../../flyway</relativePath>
-	</parent>
-
-	<properties>
-		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-		<java.version>1.8</java.version>
-	</properties>
-
-	<dependencies>
-		<dependency>
-			<groupId>org.flywaydb</groupId>
-			<artifactId>flyway-core</artifactId>
-			<version>5.0.2</version>
-		</dependency>
-
-		<dependency>
-			<groupId>org.springframework.boot</groupId>
-			<artifactId>spring-boot-starter-jdbc</artifactId>
-		</dependency>
-
-		<dependency>
-			<groupId>com.h2database</groupId>
-			<artifactId>h2</artifactId>
-		</dependency>
-		<dependency>
-			<groupId>org.springframework.boot</groupId>
-			<artifactId>spring-boot-starter-test</artifactId>
-			<scope>test</scope>
-		</dependency>
-	</dependencies>
-
-	<build>
-		<plugins>
-			<plugin>
-				<groupId>org.springframework.boot</groupId>
-				<artifactId>spring-boot-maven-plugin</artifactId>
-			</plugin>
-		</plugins>
-	</build>
-
-
-</project>

flyway/pom.xml

@@ -0,0 +1,70 @@
+<?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>flyway</artifactId>
+    <packaging>jar</packaging>
+
+    <name>flyway</name>
+    <description>Flyway Callbacks Demo</description>
+
+    <parent>
+        <artifactId>parent-boot-5</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../parent-boot-5</relativePath>
+    </parent>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+        <java.version>1.8</java.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.flywaydb</groupId>
+            <artifactId>flyway-core</artifactId>
+            <version>5.0.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-jdbc</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>mysql</groupId>
+            <artifactId>mysql-connector-java</artifactId>
+            <version>6.0.3</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.flywaydb</groupId>
+                <artifactId>flyway-maven-plugin</artifactId>
+                <version>5.0.2</version>
+            </plugin>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+            </plugin>
+        </plugins>
+    </build>
+
+
+</project>