Merge remote-tracking branch 'eugenp/master'

2018-03-01 13:24:36 +02:00
parent 1d42f7c9bd 00f5648b39
commit 237ea1b565
79 changed files with 1933 additions and 431 deletions
@@ -0,0 +1,30 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<groupId>com.baeldung</groupId>
+	<artifactId>apache-zookeeper</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<packaging>jar</packaging>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.apache.zookeeper</groupId>
+			<artifactId>zookeeper</artifactId>
+			<version>3.3.2</version>
+			<exclusions>
+				<exclusion>
+					<groupId>com.sun.jmx</groupId>
+					<artifactId>jmxri</artifactId>
+				</exclusion>
+				<exclusion>
+					<groupId>com.sun.jdmk</groupId>
+					<artifactId>jmxtools</artifactId>
+				</exclusion>
+				<exclusion>
+					<groupId>javax.jms</groupId>
+					<artifactId>jms</artifactId>
+				</exclusion>
+			</exclusions>
+		</dependency>
+	</dependencies>
+</project>
@@ -0,0 +1,33 @@
+package com.baeldung.zookeeper.connection;
+
+import java.io.IOException;
+import java.util.concurrent.CountDownLatch;
+
+import org.apache.zookeeper.WatchedEvent;
+import org.apache.zookeeper.Watcher;
+import org.apache.zookeeper.Watcher.Event.KeeperState;
+import org.apache.zookeeper.ZooKeeper;
+
+public class ZKConnection {
+    private ZooKeeper zoo;
+    final CountDownLatch connectionLatch = new CountDownLatch(1);
+
+    public ZKConnection() {
+    }
+
+    public ZooKeeper connect(String host) throws IOException, InterruptedException {
+        zoo = new ZooKeeper(host, 2000, new Watcher() {
+            public void process(WatchedEvent we) {
+                if (we.getState() == KeeperState.SyncConnected) {
+                    connectionLatch.countDown();
+                }
+            }
+        });
+        connectionLatch.await();
+        return zoo;
+    }
+
+    public void close() throws InterruptedException {
+        zoo.close();
+    }
+}
@@ -0,0 +1,35 @@
+package com.baeldung.zookeeper.manager;
+
+import org.apache.zookeeper.KeeperException;
+
+public interface ZKManager {
+    /**
+     * Create a Znode and save some data
+     * 
+     * @param path
+     * @param data
+     * @throws KeeperException
+     * @throws InterruptedException
+     */
+    public void create(String path, byte[] data) throws KeeperException, InterruptedException;
+
+    /**
+     * Get ZNode Data
+     * 
+     * @param path
+     * @param boolean watchFlag
+     * @throws KeeperException
+     * @throws InterruptedException
+     */
+    public Object getZNodeData(String path, boolean watchFlag);
+
+    /**
+     * Update the ZNode Data
+     * 
+     * @param path
+     * @param data
+     * @throws KeeperException
+     * @throws InterruptedException
+     */
+    public void update(String path, byte[] data) throws KeeperException, InterruptedException, KeeperException;
+}
@@ -0,0 +1,58 @@
+package com.baeldung.zookeeper.manager;
+
+import org.apache.zookeeper.CreateMode;
+import org.apache.zookeeper.KeeperException;
+import org.apache.zookeeper.ZooDefs;
+import org.apache.zookeeper.ZooKeeper;
+
+import com.baeldung.zookeeper.connection.ZKConnection;
+
+public class ZKManagerImpl implements ZKManager {
+    private static ZooKeeper zkeeper;
+    private static ZKConnection zkConnection;
+
+    public ZKManagerImpl() {
+        initialize();
+    }
+
+    /** * Initialize connection */
+    private void initialize() {
+        try {
+            zkConnection = new ZKConnection();
+            zkeeper = zkConnection.connect("localhost");
+        } catch (Exception e) {
+            System.out.println(e.getMessage());
+        }
+    }
+
+    public void closeConnection() {
+        try {
+            zkConnection.close();
+        } catch (InterruptedException e) {
+            System.out.println(e.getMessage());
+        }
+    }
+
+    public void create(String path, byte[] data) throws KeeperException, InterruptedException {
+        zkeeper.create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
+    }
+
+    public Object getZNodeData(String path, boolean watchFlag) {
+        try {
+            byte[] b = null;
+            b = zkeeper.getData(path, null, null);
+            String data = new String(b, "UTF-8");
+            System.out.println(data);
+            return data;
+        } catch (Exception e) {
+            System.out.println(e.getMessage());
+        }
+        return null;
+    }
+
+    public void update(String path, byte[] data) throws KeeperException, InterruptedException {
+        int version = zkeeper.exists(path, true)
+            .getVersion();
+        zkeeper.setData(path, data, version);
+    }
+}
@@ -0,0 +1,13 @@
+group 'com.baeldung'
+version '1.0-SNAPSHOT'
+
+apply plugin: 'groovy'
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    compile 'org.codehaus.groovy:groovy-all:2.5.0-alpha-1'
+    testCompile 'org.spockframework:spock-core:1.1-groovy-2.4'
+}
@@ -1,6 +1,5 @@
 <?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">
+<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-groovy</artifactId>
@@ -24,12 +23,17 @@
        <dependency>
            <groupId>org.codehaus.groovy</groupId>
            <artifactId>groovy</artifactId>
-            <version>2.4.13</version>
+            <version>2.5.0-alpha-1</version>
+        </dependency>
+        <dependency>
+            <groupId>org.codehaus.groovy</groupId>
+            <artifactId>groovy-all</artifactId>
+            <version>2.5.0-alpha-1</version>
        </dependency>
        <dependency>
            <groupId>org.codehaus.groovy</groupId>
            <artifactId>groovy-sql</artifactId>
-            <version>2.4.13</version>
+            <version>2.5.0-alpha-1</version>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
@@ -49,6 +53,12 @@
            <version>2.4.0</version>
            <scope>test</scope>
        </dependency>
+        <dependency>
+            <groupId>org.spockframework</groupId>
+            <artifactId>spock-core</artifactId>
+            <version>1.1-groovy-2.4</version>
+            <scope>test</scope>
+        </dependency>
    </dependencies>

    <build>
@@ -114,5 +124,5 @@
        <junit.vintage.version>4.12.0</junit.vintage.version>
        <junit4.version>4.12</junit4.version>
    </properties>
-
 </project>
+
@@ -0,0 +1,7 @@
+package com.baeldung.json
+
+class Account {
+    String id
+    BigDecimal value
+    Date createdAt
+}
@@ -0,0 +1,36 @@
+package com.baeldung.json
+
+import groovy.json.JsonGenerator
+import groovy.json.JsonOutput
+import groovy.json.JsonParserType
+import groovy.json.JsonSlurper
+
+class JsonParser {
+
+    Account toObject(String json) {
+        JsonSlurper jsonSlurper = new JsonSlurper()
+        jsonSlurper.parseText(json) as Account
+    }
+
+    Account toObjectWithIndexOverlay(String json) {
+        JsonSlurper jsonSlurper = new JsonSlurper(type: JsonParserType.INDEX_OVERLAY)
+        jsonSlurper.parseText(json) as Account
+    }
+
+    String toJson(Account account) {
+        JsonOutput.toJson(account)
+    }
+
+    String toJson(Account account, String dateFormat, String... fieldsToExclude) {
+        JsonGenerator generator = new JsonGenerator.Options()
+                .dateFormat(dateFormat)
+                .excludeFieldsByName(fieldsToExclude)
+                .build()
+        generator.toJson(account)
+    }
+
+    String prettyfy(String json) {
+        JsonOutput.prettyPrint(json)
+    }
+
+}
@@ -0,0 +1,80 @@
+package com.baeldung.json
+
+import spock.lang.Specification
+
+import java.text.SimpleDateFormat
+
+class JsonParserTest extends Specification {
+
+    JsonParser jsonParser
+
+    void setup () {
+        jsonParser = new JsonParser()
+    }
+
+    def 'Should parse to Account given Json String' () {
+        given:
+            def json = '{"id":"1234","value":15.6}'
+        when:
+            def account = jsonParser.toObject(json)
+        then:
+            account
+            account instanceof Account
+            account.id == '1234'
+            account.value == 15.6
+    }
+
+    def 'Should parse to Account given Json String with date property' () {
+        given:
+            def json = '{"id":"1234","value":15.6,"createdAt":"2018-01-01T00:00:00+0000"}'
+        when:
+            def account = jsonParser.toObjectWithIndexOverlay(json)
+        then:
+            account
+            account instanceof Account
+            account.id == '1234'
+            account.value == 15.6
+            println account.createdAt
+            account.createdAt == Date.parse('yyyy-MM-dd', '2018-01-01')
+    }
+
+    def 'Should parse to Json given an Account object' () {
+        given:
+            Account account = new Account(
+                    id: '123',
+                    value: 15.6,
+                    createdAt: new SimpleDateFormat('MM/dd/yyyy').parse('01/01/2018')
+            )
+        when:
+            def json = jsonParser.toJson(account)
+        then:
+            json
+            json == '{"value":15.6,"createdAt":"2018-01-01T00:00:00+0000","id":"123"}'
+    }
+
+    def 'Should parse to Json given an Account object, a date format and fields to exclude' () {
+        given:
+            Account account = new Account(
+                    id: '123',
+                    value: 15.6,
+                    createdAt: new SimpleDateFormat('MM/dd/yyyy').parse('01/01/2018')
+            )
+        when:
+            def json = jsonParser.toJson(account, 'MM/dd/yyyy', 'value')
+        then:
+            json
+            json == '{"createdAt":"01/01/2018","id":"123"}'
+    }
+
+    def 'Should prettify given a json string' () {
+        given:
+            String json = '{"value":15.6,"createdAt":"01/01/2018","id":"123456"}'
+        when:
+            def jsonPretty = jsonParser.prettyfy(json)
+        then:
+            jsonPretty
+            jsonPretty == '{\n    "value": 15.6,\n    "createdAt": "01/01/2018",\n    "id": "123456"\n}'
+    }
+
+
+}
@@ -0,0 +1,17 @@
+package com.baeldung.java9.methodhandles;
+
+public class Book {
+
+    String id;
+    String title;
+
+    public Book(String id, String title) {
+        this.id = id;
+        this.title = title;
+    }
+
+    @SuppressWarnings("unused")
+    private String formatBook() {
+        return id + " > " + title;
+    }
+}
@@ -0,0 +1,152 @@
+package com.baeldung.java9.methodhandles;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.*;
+
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.lang.invoke.WrongMethodTypeException;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.Test;
+
+/**
+ * Test case for the {@link MethodHandles} API
+ */
+public class MethodHandlesTest {
+
+    @Test
+    public void givenConcatMethodHandle_whenInvoked_thenCorrectlyConcatenated() throws Throwable {
+
+        MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
+        MethodType mt = MethodType.methodType(String.class, String.class);
+        MethodHandle concatMH = publicLookup.findVirtual(String.class, "concat", mt);
+
+        String output = (String) concatMH.invoke("Effective ", "Java");
+
+        assertEquals("Effective Java", output);
+    }
+
+    @Test
+    public void givenAsListMethodHandle_whenInvokingWithArguments_thenCorrectlyInvoked() throws Throwable {
+        MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
+        MethodType mt = MethodType.methodType(List.class, Object[].class);
+        MethodHandle asListMH = publicLookup.findStatic(Arrays.class, "asList", mt);
+
+        List<Integer> list = (List<Integer>) asListMH.invokeWithArguments(1, 2);
+
+        assertThat(Arrays.asList(1, 2), is(list));
+    }
+
+    @Test
+    public void givenConstructorMethodHandle_whenInvoked_thenObjectCreatedCorrectly() throws Throwable {
+        MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
+        MethodType mt = MethodType.methodType(void.class, String.class);
+        MethodHandle newIntegerMH = publicLookup.findConstructor(Integer.class, mt);
+
+        Integer integer = (Integer) newIntegerMH.invoke("1");
+
+        assertEquals(1, integer.intValue());
+    }
+
+    @Test
+    public void givenAFieldWithoutGetter_whenCreatingAGetter_thenCorrectlyInvoked() throws Throwable {
+        MethodHandles.Lookup lookup = MethodHandles.lookup();
+        MethodHandle getTitleMH = lookup.findGetter(Book.class, "title", String.class);
+
+        Book book = new Book("ISBN-1234", "Effective Java");
+
+        assertEquals("Effective Java", getTitleMH.invoke(book));
+    }
+
+    @Test
+    public void givenPrivateMethod_whenCreatingItsMethodHandle_thenCorrectlyInvoked() throws Throwable {
+        MethodHandles.Lookup lookup = MethodHandles.lookup();
+        Method formatBookMethod = Book.class.getDeclaredMethod("formatBook");
+        formatBookMethod.setAccessible(true);
+
+        MethodHandle formatBookMH = lookup.unreflect(formatBookMethod);
+
+        Book book = new Book("ISBN-123", "Java in Action");
+
+        assertEquals("ISBN-123 > Java in Action", formatBookMH.invoke(book));
+    }
+
+    @Test
+    public void givenReplaceMethod_whenUsingReflectionAndInvoked_thenCorrectlyReplaced() throws Throwable {
+        Method replaceMethod = String.class.getMethod("replace", char.class, char.class);
+
+        String string = (String) replaceMethod.invoke("jovo", 'o', 'a');
+
+        assertEquals("java", string);
+    }
+
+    @Test
+    public void givenReplaceMethodHandle_whenInvoked_thenCorrectlyReplaced() throws Throwable {
+        MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
+        MethodType mt = MethodType.methodType(String.class, char.class, char.class);
+        MethodHandle replaceMH = publicLookup.findVirtual(String.class, "replace", mt);
+
+        String replacedString = (String) replaceMH.invoke("jovo", Character.valueOf('o'), 'a');
+
+        assertEquals("java", replacedString);
+    }
+
+    @Test
+    public void givenReplaceMethodHandle_whenInvokingExact_thenCorrectlyReplaced() throws Throwable {
+        MethodHandles.Lookup lookup = MethodHandles.lookup();
+        MethodType mt = MethodType.methodType(String.class, char.class, char.class);
+        MethodHandle replaceMH = lookup.findVirtual(String.class, "replace", mt);
+
+        String s = (String) replaceMH.invokeExact("jovo", 'o', 'a');
+
+        assertEquals("java", s);
+    }
+
+    @Test
+    public void givenSumMethodHandle_whenInvokingExact_thenSumIsCorrect() throws Throwable {
+        MethodHandles.Lookup lookup = MethodHandles.lookup();
+        MethodType mt = MethodType.methodType(int.class, int.class, int.class);
+        MethodHandle sumMH = lookup.findStatic(Integer.class, "sum", mt);
+
+        int sum = (int) sumMH.invokeExact(1, 11);
+
+        assertEquals(12, sum);
+    }
+
+    @Test(expected = WrongMethodTypeException.class)
+    public void givenSumMethodHandleAndIncompatibleArguments_whenInvokingExact_thenException() throws Throwable {
+        MethodHandles.Lookup lookup = MethodHandles.lookup();
+        MethodType mt = MethodType.methodType(int.class, int.class, int.class);
+        MethodHandle sumMH = lookup.findStatic(Integer.class, "sum", mt);
+
+        sumMH.invokeExact(Integer.valueOf(1), 11);
+    }
+
+    @Test
+    public void givenSpreadedEqualsMethodHandle_whenInvokedOnArray_thenCorrectlyEvaluated() throws Throwable {
+        MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
+        MethodType mt = MethodType.methodType(boolean.class, Object.class);
+        MethodHandle equalsMH = publicLookup.findVirtual(String.class, "equals", mt);
+
+        MethodHandle methodHandle = equalsMH.asSpreader(Object[].class, 2);
+
+        assertTrue((boolean) methodHandle.invoke(new Object[] { "java", "java" }));
+        assertFalse((boolean) methodHandle.invoke(new Object[] { "java", "jova" }));
+    }
+
+    @Test
+    public void givenConcatMethodHandle_whenBindToAString_thenCorrectlyConcatenated() throws Throwable {
+        MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
+        MethodType mt = MethodType.methodType(String.class, String.class);
+        MethodHandle concatMH = publicLookup.findVirtual(String.class, "concat", mt);
+
+        MethodHandle bindedConcatMH = concatMH.bindTo("Hello ");
+
+        assertEquals("Hello World!", bindedConcatMH.invoke("World!"));
+    }
+}
@@ -128,3 +128,4 @@
 - [Recursion In Java](http://www.baeldung.com/java-recursion)
 - [A Guide to the finalize Method in Java](http://www.baeldung.com/java-finalize)
 - [Compiling Java *.class Files with javac](http://www.baeldung.com/javac)
+- [Method Overloading and Overriding in Java](http://www.baeldung.com/java-method-overload-override)
@@ -0,0 +1,43 @@
+package com.baeldung.inheritance;
+
+public class ArmoredCar extends Car implements Floatable, Flyable{
+    private int bulletProofWindows;
+    private String model;
+    
+    public void remoteStartCar() {
+        // this vehicle can be started by using a remote control
+    }
+    
+    public String registerModel() {
+        return model;
+    }
+    
+    public String getAValue() {
+        return super.model;   // returns value of model defined in base class Car
+        // return this.model;   // will return value of model defined in ArmoredCar
+        // return model;   // will return value of model defined in ArmoredCar
+    }
+    
+    public static String msg() {
+    	// return super.msg(); // this won't compile.
+    	return "ArmoredCar"; 
+    }
+    
+	@Override
+    public void floatOnWater() {
+        System.out.println("I can float!");
+    }
+    
+	@Override
+    public void fly() {
+        System.out.println("I can fly!");
+    }
+    
+    public void aMethod() {
+        // System.out.println(duration); // Won't compile
+        System.out.println(Floatable.duration); // outputs 10
+        System.out.println(Flyable.duration); // outputs 20
+    }
+    
+    
+}
@@ -0,0 +1,12 @@
+package com.baeldung.inheritance;
+
+public class BMW extends Car {
+    public BMW() {
+    	super(5, "BMW");
+    }
+	
+	@Override
+    public String toString() {
+    	return model;
+    }
+}
@@ -0,0 +1,32 @@
+package com.baeldung.inheritance;
+
+public class Car {
+	private final int DEFAULT_WHEEL_COUNT = 5;
+	private final String DEFAULT_MODEL = "Basic";
+
+	protected int wheels;
+    protected String model;
+    
+    public Car() {
+    	this.wheels = DEFAULT_WHEEL_COUNT;
+    	this.model = DEFAULT_MODEL;
+    }
+    
+    public Car(int wheels, String model) {
+    	this.wheels = wheels;
+    	this.model = model;
+    }
+        
+    public void start() {
+        // Check essential parts
+        // If okay, start.
+    }
+    public static int count = 10;
+    public static String msg() {
+        return "Car";
+    }
+    
+    public String toString() {
+    	return model;
+    } 
+}
@@ -0,0 +1,15 @@
+package com.baeldung.inheritance;
+
+public class Employee {
+    private String name;
+    private Car car;
+    
+    public Employee(String name, Car car) {
+        this.name = name;
+        this.car = car;
+    }
+    
+    public Car getCar() {
+    	return car;
+    }
+}
@@ -0,0 +1,10 @@
+package com.baeldung.inheritance;
+
+public interface Floatable {
+    int duration = 10;
+    void floatOnWater();
+    
+    default void repair() {
+        System.out.println("Repairing Floatable object");   
+    }
+}
@@ -0,0 +1,13 @@
+package com.baeldung.inheritance;
+
+public interface Flyable {
+    int duration = 10;
+    void fly();
+    
+    /*
+     * Commented 
+     */
+    //default void repair() {
+    //    System.out.println("Repairing Flyable object"); 
+    //}
+}
@@ -0,0 +1,18 @@
+package com.baeldung.inheritance;
+
+public class SpaceCar extends Car implements SpaceTraveller {
+	@Override
+    public void floatOnWater() {
+        System.out.println("SpaceCar floating!");
+    }
+    
+	@Override
+    public void fly() {
+        System.out.println("SpaceCar flying!");
+    }
+    
+	@Override
+    public void remoteControl() {
+        System.out.println("SpaceCar being controlled remotely!");
+    }
+}
@@ -0,0 +1,6 @@
+package com.baeldung.inheritance;
+
+public interface SpaceTraveller extends Floatable, Flyable {
+    int duration = 10;
+    void remoteControl();
+}
@@ -9,6 +9,58 @@ import java.util.ListIterator;
 public class CustomList<E> implements List<E> {
    private Object[] internal = {};

+    @Override
+    public boolean isEmpty() {
+        // the first cycle
+        // return true;
+
+        // the second cycle
+        // if (internal.length != 0) {
+        //     return false;
+        // } else {
+        //     return true;
+        // }
+
+        // refactoring
+        return internal.length == 0;
+    }
+
+    @Override
+    public int size() {
+        // the first cycle
+        // if (isEmpty()) {
+        //     return 0;
+        // } else {
+        //     return internal.length;
+        // }
+
+        // refactoring
+        return internal.length;
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public E get(int index) {
+        // the first cycle
+        // return (E) internal[0];
+
+        // improvement
+        return (E) internal[index];
+    }
+
+    @Override
+    public boolean add(E element) {
+        // the first cycle
+        // internal = new Object[] { element };
+        // return true;
+
+        // the second cycle
+        Object[] temp = Arrays.copyOf(internal, internal.length + 1);
+        temp[internal.length] = element;
+        internal = temp;
+        return true;
+    }
+
    @Override
    public void add(int index, E element) {
        throw new UnsupportedOperationException();
@@ -44,40 +96,8 @@ public class CustomList<E> implements List<E> {
        throw new UnsupportedOperationException();
    }

-    @Override
-    public int size() {
-        return internal.length;
-    }
-
-    @Override
-    public boolean isEmpty() {
-        return internal.length == 0;
-    }
-
-    @Override
-    public boolean add(E element) {
-        // the first cycle
-        // internal = new Object[1];
-        // internal[0] = element;
-        // return true;
-
-        Object[] temp = new Object[internal.length + 1];
-        System.arraycopy(internal, 0, temp, 0, internal.length);
-        temp[internal.length] = element;
-        internal = temp;
-        return true;
-    }
-
-    @SuppressWarnings("unchecked")
-    @Override
-    public E get(int index) {
-        return (E) internal[index];
-    }
-
    @Override
    public boolean contains(Object object) {
-        // return false
-
        for (Object element : internal) {
            if (object.equals(element)) {
                return true;
@@ -88,14 +108,6 @@ public class CustomList<E> implements List<E> {

    @Override
    public boolean containsAll(Collection<?> collection) {
-        // the first cycle
-        // for (Object element : collection) {
-        //     if (element.equals(internal[0])) {
-        //         return true;
-        //     }
-        // }
-        // return false;
-
        for (Object element : collection)
            if (!contains(element)) {
                return false;
@@ -118,12 +130,6 @@ public class CustomList<E> implements List<E> {

    @Override
    public int indexOf(Object object) {
-        // the first cycle
-        // if (object.equals(internal[0])) {
-        //     return 0;
-        // }
-        // return -1;
-
        for (int i = 0; i < internal.length; i++) {
            if (object.equals(internal[i])) {
                return i;
@@ -134,12 +140,6 @@ public class CustomList<E> implements List<E> {

    @Override
    public int lastIndexOf(Object object) {
-        // the first cycle
-        // if (object.equals(internal[0])) {
-        //     return 0;
-        // }
-        // return -1;
-
        for (int i = internal.length - 1; i >= 0; i--) {
            if (object.equals(internal[i])) {
                return i;
@@ -151,9 +151,6 @@ public class CustomList<E> implements List<E> {
    @SuppressWarnings("unchecked")
    @Override
    public List<E> subList(int fromIndex, int toIndex) {
-        // the first cycle
-        // return (List<E>) Arrays.asList(internal);
-
        Object[] temp = new Object[toIndex - fromIndex];
        System.arraycopy(internal, fromIndex, temp, 0, temp.length);
        return (List<E>) Arrays.asList(temp);
@@ -167,16 +164,6 @@ public class CustomList<E> implements List<E> {
    @SuppressWarnings("unchecked")
    @Override
    public <T> T[] toArray(T[] array) {
-        // the first cycle
-        // array[0] = (T) internal[0];
-        // return array;
-
-        // the second cycle
-        // if (array.length < internal.length) {
-        //     return (T[]) Arrays.copyOf(internal, internal.length, array.getClass());
-        // }
-        // return (T[]) Arrays.copyOf(internal, internal.length, array.getClass());
-
        if (array.length < internal.length) {
            return (T[]) Arrays.copyOf(internal, internal.length, array.getClass());
        }
@@ -209,18 +196,12 @@ public class CustomList<E> implements List<E> {

        @Override
        public boolean hasNext() {
-            // the first cycle
-            // return true;
-
            return index != internal.length;
        }

        @SuppressWarnings("unchecked")
        @Override
        public E next() {
-            // the first cycle
-            // return (E) CustomList.this.internal[0];
-
            E element = (E) CustomList.this.internal[index];
            index++;
            return element;
@@ -0,0 +1,18 @@
+package com.baeldung.system;
+
+import org.apache.commons.lang3.SystemUtils;
+
+public class DetectOS {
+
+    public String getOperatingSystem() {
+        String os = System.getProperty("os.name");
+        System.out.println("Using System Property: " + os);
+        return os;
+    }
+
+    public String getOperatingSystemSystemUtils() {
+        String os = SystemUtils.OS_NAME;
+        System.out.println("Using SystemUtils: " + os);
+        return os;
+    }
+}
@@ -0,0 +1,46 @@
+package com.baeldung.inheritance;
+
+import com.baeldung.inheritance.*;
+
+import junit.framework.Test;
+import junit.framework.TestCase;
+import junit.framework.TestSuite;
+
+public class AppTest extends TestCase {
+    
+	public AppTest(String testName) {
+        super( testName );
+    }
+
+    public static Test suite() {
+        return new TestSuite(AppTest.class);
+    }
+
+    @SuppressWarnings("static-access")
+	public void testStaticMethodUsingBaseClassVariable() {
+    	Car first = new ArmoredCar();
+    	assertEquals("Car", first.msg());
+    }
+    	
+    @SuppressWarnings("static-access")
+	public void testStaticMethodUsingDerivedClassVariable() {
+    	ArmoredCar second = new ArmoredCar();
+    	assertEquals("ArmoredCar", second.msg());
+    }
+    
+    public void testAssignArmoredCarToCar() {
+    	Employee e1 = new Employee("Shreya", new ArmoredCar());
+    	assertNotNull(e1.getCar());
+    }
+
+    public void testAssignSpaceCarToCar() {
+    	Employee e2 = new Employee("Paul", new SpaceCar());
+    	assertNotNull(e2.getCar());
+    }
+
+    public void testBMWToCar() {
+    	Employee e3 = new Employee("Pavni", new BMW());
+    	assertNotNull(e3.getCar());
+    }
+
+}
@@ -14,6 +14,58 @@ import java.util.List;
 import org.junit.Test;

 public class CustomListUnitTest {
+     @Test
+     public void givenEmptyList_whenIsEmpty_thenTrueIsReturned() {
+         List<Object> list = new CustomList<>();
+    
+         assertTrue(list.isEmpty());
+     }
+     
+     @Test
+     public void givenNonEmptyList_whenIsEmpty_thenFalseIsReturned() {
+         List<Object> list = new CustomList<>();
+         list.add(null);
+      
+         assertFalse(list.isEmpty());
+     }
+     
+     @Test
+     public void givenListWithAnElement_whenSize_thenOneIsReturned() {
+         List<Object> list = new CustomList<>();
+         list.add(null);
+      
+         assertEquals(1, list.size());
+     }
+     
+     @Test
+     public void givenListWithAnElement_whenGet_thenThatElementIsReturned() {
+         List<Object> list = new CustomList<>();
+         list.add("baeldung");
+         Object element = list.get(0);
+      
+         assertEquals("baeldung", element);
+     }
+     
+     @Test
+     public void givenEmptyList_whenElementIsAdded_thenGetReturnsThatElement() {
+         List<Object> list = new CustomList<>();
+         boolean succeeded = list.add(null);
+      
+         assertTrue(succeeded);
+     }
+     
+     @Test
+     public void givenListWithAnElement_whenAnotherIsAdded_thenGetReturnsBoth() {
+         List<Object> list = new CustomList<>();
+         list.add("baeldung");
+         list.add(".com");
+         Object element1 = list.get(0);
+         Object element2 = list.get(1);
+
+         assertEquals("baeldung", element1);
+         assertEquals(".com", element2);
+     }
+    
    @Test(expected = UnsupportedOperationException.class)
    public void whenAddToSpecifiedIndex_thenExceptionIsThrown() {
        new CustomList<>().add(0, null);
@@ -64,44 +116,6 @@ public class CustomListUnitTest {
        list.retainAll(collection);
    }

-    @Test
-    public void givenEmptyList_whenSize_thenZeroIsReturned() {
-        List<Object> list = new CustomList<>();
-
-        assertEquals(0, list.size());
-    }
-
-    @Test
-    public void givenEmptyList_whenIsEmpty_thenTrueIsReturned() {
-        List<Object> list = new CustomList<>();
-
-        assertTrue(list.isEmpty());
-    }
-
-    @Test
-    public void givenEmptyList_whenElementIsAdded_thenGetReturnsThatElement() {
-        List<Object> list = new CustomList<>();
-        boolean succeeded = list.add("baeldung");
-        Object element = list.get(0);
-
-        assertTrue(succeeded);
-        assertEquals("baeldung", element);
-    }
-
-    @Test
-    public void givenListWithAnElement_whenAnotherIsAdded_thenGetReturnsBoth() {
-        List<Object> list = new CustomList<>();
-        boolean succeeded1 = list.add("baeldung");
-        boolean succeeded2 = list.add(".com");
-        Object element1 = list.get(0);
-        Object element2 = list.get(1);
-
-        assertTrue(succeeded1);
-        assertTrue(succeeded2);
-        assertEquals("baeldung", element1);
-        assertEquals(".com", element2);
-    }
-
    @Test
    public void givenEmptyList_whenContains_thenFalseIsReturned() {
        List<Object> list = new CustomList<>();
@@ -271,7 +285,7 @@ public class CustomListUnitTest {
    }

    @Test
-    public void whenIteratorNextIsCalledTwice_thenTheSecondReturnsFalse() {
+    public void whenIteratorHasNextIsCalledTwice_thenTheSecondReturnsFalse() {
        List<Object> list = new CustomList<>();
        list.add("baeldung");
        Iterator<Object> iterator = list.iterator();
@@ -0,0 +1,25 @@
+package com.baeldung.system;
+
+import org.junit.Assert;
+import org.junit.Ignore;
+import org.junit.Test;
+
+@Ignore
+public class WhenDetectingOSTest {
+
+    private DetectOS os = new DetectOS();
+
+    @Test
+    public void whenUsingSystemProperty_shouldReturnOS() {
+        String expected = "Windows 10";
+        String actual = os.getOperatingSystem();
+        Assert.assertEquals(expected, actual);
+    }
+
+    @Test
+    public void whenUsingSystemUtils_shouldReturnOS() {
+        String expected = "Windows 10";
+        String actual = os.getOperatingSystemSystemUtils();
+        Assert.assertEquals(expected, actual);
+    }
+}
@@ -76,7 +76,18 @@
            <artifactId>mockito-kotlin</artifactId>
            <version>${mockito-kotlin.version}</version>
            <scope>test</scope>
-        </dependency>        
+        </dependency>
+        <dependency>
+            <groupId>com.github.salomonbrys.kodein</groupId>
+            <artifactId>kodein</artifactId>
+            <version>${kodein.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
    </dependencies>

    <build>
@@ -189,11 +200,13 @@
        <kotlin-reflect.version>1.1.2</kotlin-reflect.version>
        <kotlinx.version>0.15</kotlinx.version>
        <mockito-kotlin.version>1.5.0</mockito-kotlin.version>
+        <kodein.version>4.1.0</kodein.version>

        <junit.jupiter.version>5.0.0</junit.jupiter.version>
        <junit.platform.version>1.0.0</junit.platform.version>
        <junit.vintage.version>4.12.0</junit.vintage.version>
        <junit4.version>4.12</junit4.version>
+        <assertj.version>3.9.1</assertj.version>
    </properties>

 </project>
@@ -0,0 +1,3 @@
+package com.baeldung.kotlin.kodein
+
+class Controller(private val service : Service)
@@ -0,0 +1,3 @@
+package com.baeldung.kotlin.kodein
+
+interface Dao
@@ -0,0 +1,3 @@
+package com.baeldung.kotlin.kodein
+
+class JdbcDao : Dao
@@ -0,0 +1,3 @@
+package com.baeldung.kotlin.kodein
+
+class MongoDao : Dao
--- a/Show More
+++ b/Show More