Merge pull request #4 from eugenp/master

Update

activejdbc/pom.xml

@@ -0,0 +1,129 @@
+<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>activejdbc</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <packaging>jar</packaging>
+  <name>activejdbc</name>
+  <url>http://maven.apache.org</url>
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <activejdbc.version>1.4.13</activejdbc.version>
+    <environments>development.test,development</environments>
+  </properties>
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.6.0</version>
+        <configuration>
+          <source>1.8</source>
+          <target>1.8</target>
+          <encoding>UTF-8</encoding>
+        </configuration>
+      </plugin>
+      <plugin>
+        <groupId>org.javalite</groupId>
+        <artifactId>activejdbc-instrumentation</artifactId>
+        <version>${activejdbc.version}</version>
+        <executions>
+          <execution>
+            <phase>process-classes</phase>
+            <goals>
+              <goal>instrument</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
+      <plugin>
+        <groupId>org.javalite</groupId>
+        <artifactId>db-migrator-maven-plugin</artifactId>
+        <version>${activejdbc.version}</version>
+        <configuration>
+          <configFile>${project.basedir}/src/main/resources/database.properties</configFile>
+          <environments>${environments}</environments>
+        </configuration>
+        <dependencies>
+          <dependency>
+            <groupId>mysql</groupId>
+            <artifactId>mysql-connector-java</artifactId>
+            <version>5.1.34</version>
+          </dependency>
+        </dependencies>
+      </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <version>2.18.1</version>
+        <configuration>
+          <reportFormat>brief</reportFormat>
+          <trimStackTrace>true</trimStackTrace>
+          <useFile>false</useFile>
+          <includes>
+            <include>**/*Spec*.java</include>
+            <include>**/*Test*.java</include>
+          </includes>
+          <excludes>
+            <exclude>**/helpers/*</exclude>
+            <exclude>**/*$*</exclude>
+          </excludes>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+  <dependencies>
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.12</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.javalite</groupId>
+      <artifactId>activejdbc</artifactId>
+      <version>${activejdbc.version}</version>
+      <exclusions>
+        <exclusion>
+          <groupId>opensymphony</groupId>
+          <artifactId>oscache</artifactId>
+        </exclusion>
+      </exclusions>
+    </dependency>
+    <dependency>
+      <groupId>mysql</groupId>
+      <artifactId>mysql-connector-java</artifactId>
+      <version>5.1.34</version>
+    </dependency>
+    <dependency>
+      <groupId>org.slf4j</groupId>
+      <artifactId>slf4j-simple</artifactId>
+      <version>1.7.9</version>
+    </dependency>
+  </dependencies>
+  <repositories>
+    <repository>
+      <id>snapshots1</id>
+      <name>JavaLite Snapshots1</name>
+      <url>http://repo.javalite.io/</url>
+      <snapshots>
+        <enabled>true</enabled>
+        <updatePolicy>always</updatePolicy>
+        <checksumPolicy>warn</checksumPolicy>
+      </snapshots>
+    </repository>
+  </repositories>
+  <pluginRepositories>
+    <pluginRepository>
+      <id>snapshots2</id>
+      <name>JavaLite Snapshots2</name>
+      <url>http://repo.javalite.io/</url>
+      <snapshots>
+        <enabled>true</enabled>
+        <updatePolicy>always</updatePolicy>
+        <checksumPolicy>warn</checksumPolicy>
+      </snapshots>
+    </pluginRepository>
+  </pluginRepositories>
+</project>

activejdbc/src/main/java/com/baeldung/ActiveJDBCApp.java

@@ -0,0 +1,61 @@
+package com.baeldung;
+
+
+import com.baeldung.model.Employee;
+import com.baeldung.model.Role;
+import org.javalite.activejdbc.Base;
+import org.javalite.activejdbc.LazyList;
+import org.javalite.activejdbc.Model;
+
+public class ActiveJDBCApp
+{
+    public static void main( String[] args )
+    {
+        try {
+            Base.open();
+            ActiveJDBCApp app = new ActiveJDBCApp();
+            app.create();
+            app.update();
+            app.delete();
+            app.deleteCascade();
+        } catch (Exception e) {
+            e.printStackTrace();
+        } finally {
+            Base.close();
+        }
+    }
+
+    protected void create() {
+        Employee employee = new Employee("Hugo","C","M","BN");
+        employee.saveIt();
+        employee.add(new Role("Java Developer","BN"));
+        LazyList<Model> all = Employee.findAll();
+        System.out.println(all.size());
+    }
+
+    protected void update() {
+        Employee employee = Employee.findFirst("first_name = ?","Hugo");
+        employee.set("last_namea","Choi").saveIt();
+        employee = Employee.findFirst("last_name = ?","Choi");
+        System.out.println(employee.getString("first_name") + " " + employee.getString("last_name"));
+    }
+
+    protected void delete() {
+        Employee employee = Employee.findFirst("first_name = ?","Hugo");
+        employee.delete();
+        employee = Employee.findFirst("last_name = ?","Choi");
+        if(null == employee){
+            System.out.println("No such Employee found!");
+        }
+    }
+
+    protected void deleteCascade() {
+        create();
+        Employee employee = Employee.findFirst("first_name = ?","Hugo");
+        employee.deleteCascade();
+        employee = Employee.findFirst("last_name = ?","C");
+        if(null == employee){
+            System.out.println("No such Employee found!");
+        }
+    }
+}

activejdbc/src/main/java/com/baeldung/model/Employee.java

@@ -0,0 +1,19 @@
+package com.baeldung.model;
+
+
+import org.javalite.activejdbc.Model;
+
+public class Employee extends Model {
+
+    public Employee(){
+
+    }
+
+    public Employee(String firstName, String lastName, String gender, String createdBy) {
+        set("first_name1",firstName);
+        set("last_name",lastName);
+        set("gender",gender);
+        set("created_by",createdBy);
+    }
+
+}

activejdbc/src/main/java/com/baeldung/model/Role.java

@@ -0,0 +1,18 @@
+package com.baeldung.model;
+
+
+import org.javalite.activejdbc.Model;
+import org.javalite.activejdbc.annotations.Table;
+
+@Table("EMP_ROLES")
+public class Role extends Model {
+
+    public Role(){
+
+    }
+
+    public Role(String role,String createdBy){
+        set("role_name",role);
+        set("created_by",createdBy);
+    }
+}

activejdbc/src/main/migration/_create_tables.sql

@@ -0,0 +1,25 @@
+# noinspection SqlNoDataSourceInspectionForFile
+
+create table organisation.employees
+(
+	id int not null auto_increment
+		primary key,
+	first_name varchar(100) not null,
+	last_name varchar(100) not null,
+	gender varchar(1) not null,
+	created_at datetime not null,
+	updated_at datetime null,
+	created_by varchar(100) not null,
+	updated_by varchar(100) null
+)ENGINE = InnoDB DEFAULT CHARSET = utf8;
+
+create table organisation.emp_roles
+(
+	id int not null auto_increment primary key,
+	employee_id int not null,
+	role_name varchar(100) not null,
+	created_at datetime not null,
+	updated_at datetime null,
+	created_by varchar(100) not null,
+	updated_by varchar(100) null
+)ENGINE = InnoDB DEFAULT CHARSET = utf8;

activejdbc/src/main/resources/database.properties

@@ -0,0 +1,10 @@
+development.driver=com.mysql.jdbc.Driver
+development.username=root
+development.password=123456
+development.url=jdbc:mysql://localhost/organisation
+
+
+development.test.driver=com.mysql.jdbc.Driver
+development.test.username=root
+development.test.password=123456
+development.test.url=jdbc:mysql://localhost/organisation_test

activejdbc/src/test/java/com/baeldung/ActiveJDBCAppTest.java

@@ -0,0 +1,51 @@
+package com.baeldung;
+
+import com.baeldung.model.Employee;
+import com.baeldung.model.Role;
+import org.javalite.activejdbc.test.DBSpec;
+import org.junit.Test;
+
+import java.util.List;
+
+public class ActiveJDBCAppTest extends DBSpec
+{
+    @Test
+    public void ifEmployeeCreated_thenIsValid() {
+        Employee employee = new Employee("B", "N", "M", "BN");
+        the(employee).shouldBe("valid");
+    }
+
+    @Test
+    public void ifEmployeeCreatedWithRoles_thenShouldPersist() {
+        Employee employee = new Employee("B", "N", "M", "BN");
+        employee.saveIt();
+        employee.add(new Role("Java Developer","BN"));
+        employee.add(new Role("Lead Java Developer","BN"));
+        a(Role.count()).shouldBeEqual(2);
+        List<Role> roles = employee.getAll(Role.class).orderBy("created_at");
+        the(roles.get(0).getRoleName()).shouldBeEqual("Java Developer");
+        the(roles.get(1).getRoleName()).shouldBeEqual("Lead Java Developer");
+    }
+
+    @Test
+    public void ifEmployeeCreatedWithRoles_whenNameUpdated_thenShouldShowNewName() {
+        Employee employee = new Employee("Binesh", "N", "M", "BN");
+        employee.saveIt();
+        employee.add(new Role("Java Developer","BN"));
+        employee.add(new Role("Lead Java Developer","BN"));
+        employee = Employee.findFirst("first_name = ?", "Binesh");
+        employee.set("last_name","Narayanan").saveIt();
+        Employee updated = Employee.findFirst("first_name = ?", "Binesh");
+        the(updated.getLastName()).shouldBeEqual("Narayanan");
+    }
+
+    @Test
+    public void ifEmployeeCreatedWithRoles_whenDeleted_thenShouldNotBeFound() {
+        Employee employee = new Employee("Binesh", "N", "M", "BN");
+        employee.saveIt();
+        employee.add(new Role("Java Developer","BN"));
+        employee.delete();
+        employee = Employee.findFirst("first_name = ?", "Binesh");
+        the(employee).shouldBeNull();
+    }
+}

apache-poi/README.md

@@ -1,3 +1,4 @@
 ### Relevant Articles:
 - [Microsoft Word Processing in Java with Apache POI](http://www.baeldung.com/java-microsoft-word-with-apache-poi)
 - [Working with Microsoft Excel in Java](http://www.baeldung.com/java-microsoft-excel)
+- [Creating a MS PowerPoint Presentation in Java](https://github.com/eugenp/tutorials/tree/master/apache-poi)

core-java-8/README.md

@@ -37,3 +37,6 @@
 - [Iterable to Stream in Java](http://www.baeldung.com/java-iterable-to-stream)
 - [Converting String to Stream of chars](http://www.baeldung.com/java-string-to-stream)
 - [How to Iterate Over a Stream With Indices](http://www.baeldung.com/java-stream-indices)
+- [Efficient Word Frequency Calculator in Java](http://www.baeldung.com/java-word-frequency)
+- [Primitive Type Streams in Java 8](http://www.baeldung.com/java-8-primitive-streams)
+- [Fail-Safe Iterator vs Fail-Fast Iterator](http://www.baeldung.com/java-fail-safe-vs-fail-fast-iterator)

core-java-8/src/main/java/com/baeldung/spliteratorAPI/Executor.java

@@ -1,45 +1,19 @@
 package com.baeldung.spliteratorAPI;
 
-import java.util.Arrays;
 import java.util.List;
-import java.util.Spliterator;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
 import java.util.stream.Collectors;
-import java.util.stream.IntStream;
 import java.util.stream.Stream;
-import java.util.stream.StreamSupport;
 
 public class Executor {
-	public void executeCustomSpliterator() {
-        Article article = new Article(Arrays.asList(new Author("Ahmad", 0), new Author("Eugen", 0), new Author("Alice", 1), new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1),
-            new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0), new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0),
-            new Author("Alice", 1), new Author("Mike", 0), new Author("Michał", 0), new Author("Loredana", 1)), 0);
-        Stream<Author> stream = IntStream.range(0, article.getListOfAuthors()
-            .size())
-            .mapToObj(article.getListOfAuthors()::get);
-        System.out.println("count= " + countAutors(stream.parallel()));
-        Spliterator<Author> spliterator = new RelatedAuthorSpliterator(article.getListOfAuthors());
-        Stream<Author> stream2 = StreamSupport.stream(spliterator, true);
-        System.out.println("count= " + countAutors(stream2.parallel()));
-    }
 
-    public void executeSpliterator() {
-        Spliterator<Article> split1 = generateElements().spliterator();
-        Spliterator<Article> split2 = split1.trySplit();
-        ExecutorService service = Executors.newCachedThreadPool();
-        service.execute(new Task(split1));
-        service.execute(new Task(split2));
-    }
+	public static int countAutors(Stream<Author> stream) {
+		RelatedAuthorCounter wordCounter = stream.reduce(new RelatedAuthorCounter(0, true),
+				RelatedAuthorCounter::accumulate, RelatedAuthorCounter::combine);
+		return wordCounter.getCounter();
+	}
 
-    private static int countAutors(Stream<Author> stream) {
-        RelatedAuthorCounter wordCounter = stream.reduce(new RelatedAuthorCounter(0, true), RelatedAuthorCounter::accumulate, RelatedAuthorCounter::combine);
-        return wordCounter.getCounter();
-    }
+	public static List<Article> generateElements() {
+		return Stream.generate(() -> new Article("Java")).limit(35000).collect(Collectors.toList());
+	}
 
-    private List<Article> generateElements() {
-        return Stream.generate(() -> new Article("Java"))
-            .limit(35000)
-            .collect(Collectors.toList());
-    }
-}
+}

core-java-8/src/main/java/com/baeldung/spliteratorAPI/RelatedAuthorSpliterator.java

@@ -2,46 +2,48 @@ package com.baeldung.spliteratorAPI;
 
 import java.util.List;
 import java.util.Spliterator;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Consumer;
 
 public class RelatedAuthorSpliterator implements Spliterator<Author> {
-    private final List<Author> list;
-    private int current = 0;
+	private final List<Author> list;
+	AtomicInteger current = new AtomicInteger();
 
-    public RelatedAuthorSpliterator(List<Author> list) {
-        this.list = list;
-    }
+	public RelatedAuthorSpliterator(List<Author> list) {
+		this.list = list;
+	}
 
-    @Override
-    public boolean tryAdvance(Consumer<? super Author> action) {
-        action.accept(list.get(current++));
-        return current < list.size();
-    }
+	@Override
+	public boolean tryAdvance(Consumer<? super Author> action) {
 
-    @Override
-    public Spliterator<Author> trySplit() {
-        int currentSize = list.size() - current;
-        if (currentSize < 10) {
-            return null;
-        }
-        for (int splitPos = currentSize / 2 + current; splitPos < list.size(); splitPos++) {
-            if (list.get(splitPos)
-                .getRelatedArticleId() == 0) {
-                Spliterator<Author> spliterator = new RelatedAuthorSpliterator(list.subList(current, splitPos));
-                current = splitPos;
-                return spliterator;
-            }
-        }
-        return null;
-    }
+		action.accept(list.get(current.getAndIncrement()));
+		return current.get() < list.size();
+	}
 
-    @Override
-    public long estimateSize() {
-        return list.size() - current;
-    }
+	@Override
+	public Spliterator<Author> trySplit() {
+		int currentSize = list.size() - current.get();
+		if (currentSize < 10) {
+			return null;
+		}
+		for (int splitPos = currentSize / 2 + current.intValue(); splitPos < list.size(); splitPos++) {
+			if (list.get(splitPos).getRelatedArticleId() == 0) {
+				Spliterator<Author> spliterator = new RelatedAuthorSpliterator(list.subList(current.get(), splitPos));
+				current.set(splitPos);
+				return spliterator;
+			}
+		}
+		return null;
+	}
+
+	@Override
+	public long estimateSize() {
+		return list.size() - current.get();
+	}
+
+	@Override
+	public int characteristics() {
+		return CONCURRENT;
+	}
 
-    @Override
-    public int characteristics() {
-        return SIZED + CONCURRENT;
-    }
 }

core-java-8/src/main/java/com/baeldung/spliteratorAPI/Task.java

@@ -1,8 +1,9 @@
 package com.baeldung.spliteratorAPI;
 
 import java.util.Spliterator;
+import java.util.concurrent.Callable;
 
-public class Task implements Runnable {
+public class Task implements Callable<String> {
     private Spliterator<Article> spliterator;
     private final static String SUFFIX = "- published by Baeldung";
 
@@ -11,7 +12,7 @@ public class Task implements Runnable {
     }
 
     @Override
-    public void run() {
+    public String call() {
         int current = 0;
         while (spliterator.tryAdvance(article -> {
             article.setName(article.getName()
@@ -20,7 +21,7 @@ public class Task implements Runnable {
             current++;
         }
         ;
-        System.out.println(Thread.currentThread()
-            .getName() + ":" + current);
+        return Thread.currentThread()
+            .getName() + ":" + current;
     }
 }

core-java-8/src/test/java/com/baeldung/spliteratorAPI/ExecutorTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.spliteratorAPI;
+
+import java.util.Arrays;
+import java.util.Spliterator;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
+import static org.assertj.core.api.Assertions.*;
+import org.junit.Before;
+import org.junit.Test;
+
+public class ExecutorTest {
+	Article article;
+	Stream<Author> stream;
+	Spliterator<Author> spliterator;
+	Spliterator<Article> split1;
+	Spliterator<Article> split2;
+
+	@Before
+	public void init() {
+		article = new Article(Arrays.asList(new Author("Ahmad", 0), new Author("Eugen", 0), new Author("Alice", 1),
+				new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0),
+				new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0),
+				new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1),
+				new Author("Mike", 0), new Author("Alice", 1), new Author("Mike", 0), new Author("Alice", 1),
+				new Author("Mike", 0), new Author("Michał", 0), new Author("Loredana", 1)), 0);
+		stream = article.getListOfAuthors().stream();
+		split1 = Executor.generateElements().spliterator();
+		split2 = split1.trySplit();
+		spliterator = new RelatedAuthorSpliterator(article.getListOfAuthors());
+	}
+
+	@Test
+	public void givenAstreamOfAuthors_whenProcessedInParallelWithCustomSpliterator_coubtProducessRightOutput() {
+		Stream<Author> stream2 = StreamSupport.stream(spliterator, true);
+		assertThat(Executor.countAutors(stream2.parallel())).isEqualTo(9);
+	}
+
+	@Test
+	public void givenSpliterator_whenAppliedToAListOfArticle_thenSplittedInHalf() {
+		assertThat(new Task(split1).call()).containsSequence(Executor.generateElements().size() / 2 + "");
+		assertThat(new Task(split2).call()).containsSequence(Executor.generateElements().size() / 2 + "");
+	}
+}

core-java-concurrency/README.md

@@ -33,3 +33,4 @@
 - [Daemon Threads in Java](http://www.baeldung.com/java-daemon-thread)
 - [Implementing a Runnable vs Extending a Thread](http://www.baeldung.com/java-runnable-vs-extending-thread)
 - [How to Kill a Java Thread](http://www.baeldung.com/java-thread-stop)
+- [ExecutorService - Waiting for Threads to Finish](http://www.baeldung.com/java-executor-wait-for-threads)

core-java-concurrency/src/main/java/com/baeldung/concurrent/stopping/ControlSubThread.java

@@ -43,8 +43,9 @@ public class ControlSubThread implements Runnable {
             try {
                 Thread.sleep(interval);
             } catch (InterruptedException e) {
-                // no-op, just loop again
-            }
+            	Thread.currentThread().interrupt();
+                System.out.println("Thread was interrupted, Failed to complete operation");
+	    }
             // do something
         }
         stopped.set(true);

core-java-concurrency/src/main/java/com/baeldung/concurrent/waitandnotify/Data.java

@@ -1,5 +1,7 @@
 package com.baeldung.concurrent.waitandnotify;
 
+import org.slf4j.Logger;
+
 public class Data {
     private String packet;
     
@@ -11,7 +13,9 @@ public class Data {
         while (transfer) {
             try {
                 wait();
-            } catch (InterruptedException e) {}
+            } catch (InterruptedException e) {
+                System.out.println("Thread Interrupted");
+            }
         }
         transfer = true;
 
@@ -23,7 +27,9 @@ public class Data {
         while (!transfer) {
             try { 
                 wait();
-            } catch (InterruptedException e) {}
+            } catch (InterruptedException e) {
+                System.out.println("Thread Interrupted");
+            }
         }
         transfer = false;
         

core-java-concurrency/src/main/java/com/baeldung/concurrent/waitandnotify/Receiver.java

@@ -19,7 +19,9 @@ public class Receiver implements Runnable {
             //Thread.sleep() to mimic heavy server-side processing
             try {
                 Thread.sleep(ThreadLocalRandom.current().nextInt(1000, 5000));
-            } catch (InterruptedException e) {}
+            } catch (InterruptedException e) {
+                System.out.println("Thread Interrupted");
+            }
         }
     }
 }

core-java-concurrency/src/main/java/com/baeldung/concurrent/waitandnotify/Sender.java

@@ -11,11 +11,11 @@ public class Sender implements Runnable {
  
     public void run() {
         String packets[] = {
-            "First packet",
-            "Second packet",
-            "Third packet",
-            "Fourth packet",
-            "End"
+          "First packet",
+          "Second packet",
+          "Third packet",
+          "Fourth packet",
+          "End"
         };
  
         for (String packet : packets) {
@@ -24,7 +24,9 @@ public class Sender implements Runnable {
             //Thread.sleep() to mimic heavy server-side processing
             try {
                 Thread.sleep(ThreadLocalRandom.current().nextInt(1000, 5000));
-            } catch (InterruptedException e) {}
+            } catch (InterruptedException e) {
+                System.out.println("Thread Interrupted");
+            }
         }
     }
 }

core-java-concurrency/src/test/java/com/baeldung/concurrent/waitandnotify/NetworkIntegrationTest.java

@@ -13,38 +13,38 @@ import org.junit.Test;
 
 public class NetworkIntegrationTest {
 
-	private final ByteArrayOutputStream outContent = new ByteArrayOutputStream();
-	private final ByteArrayOutputStream errContent = new ByteArrayOutputStream();
-	private String expected;
-	
-	@Before
-	public void setUpStreams() {
-	    System.setOut(new PrintStream(outContent));
-	    System.setErr(new PrintStream(errContent));
-	}
-	
-	@Before
-	public void setUpExpectedOutput() {
-		StringWriter expectedStringWriter = new StringWriter();
-		
-		PrintWriter printWriter = new PrintWriter(expectedStringWriter);
-		printWriter.println("First packet");
-		printWriter.println("Second packet");
-		printWriter.println("Third packet");
-		printWriter.println("Fourth packet");
-		printWriter.close();
-		
-		expected = expectedStringWriter.toString();
-	}
+    private final ByteArrayOutputStream outContent = new ByteArrayOutputStream();
+    private final ByteArrayOutputStream errContent = new ByteArrayOutputStream();
+    private String expected;
+    
+    @Before
+    public void setUpStreams() {
+        System.setOut(new PrintStream(outContent));
+        System.setErr(new PrintStream(errContent));
+    }
+    
+    @Before
+    public void setUpExpectedOutput() {
+        StringWriter expectedStringWriter = new StringWriter();
+        
+        PrintWriter printWriter = new PrintWriter(expectedStringWriter);
+        printWriter.println("First packet");
+        printWriter.println("Second packet");
+        printWriter.println("Third packet");
+        printWriter.println("Fourth packet");
+        printWriter.close();
+        
+        expected = expectedStringWriter.toString();
+    }
 
-	@After
-	public void cleanUpStreams() {
-	    System.setOut(null);
-	    System.setErr(null);
-	}
-	
-	@Test
-	public void givenSenderAndReceiver_whenSendingPackets_thenNetworkSynchronized() {
+    @After
+    public void cleanUpStreams() {
+        System.setOut(null);
+        System.setErr(null);
+    }
+    
+    @Test
+    public void givenSenderAndReceiver_whenSendingPackets_thenNetworkSynchronized() {
         Data data = new Data();
         Thread sender = new Thread(new Sender(data));
         Thread receiver = new Thread(new Receiver(data));
@@ -54,12 +54,12 @@ public class NetworkIntegrationTest {
         
         //wait for sender and receiver to finish before we test against expected
         try {
-			sender.join();
-			receiver.join();
-		} catch (InterruptedException e) {
-			e.printStackTrace();
-		}
-		
-	    assertEquals(expected, outContent.toString());
-	}
+            sender.join();
+            receiver.join();
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+        
+        assertEquals(expected, outContent.toString());
+    }
 }

core-java/README.md

@@ -118,3 +118,12 @@
 - [Implementing a Binary Tree in Java](http://www.baeldung.com/java-binary-tree)
 - [A Guide to ThreadLocalRandom in Java](http://www.baeldung.com/java-thread-local-random)
 - [RegEx for matching Date Pattern in Java](http://www.baeldung.com/java-date-regular-expressions)
+- [Introduction to the JDBC RowSet Interface in Java](http://www.baeldung.com/java-jdbc-rowset)
+- [Nested Classes in Java](http://www.baeldung.com/java-nested-classes)
+- [A Guide to Java Loops](http://www.baeldung.com/java-loops)
+- [Varargs in Java](http://www.baeldung.com/java-varargs)
+- [A Guide to HashSet in Java](http://www.baeldung.com/java-hashset)
+- [A Guide to Inner Interfaces in Java](http://www.baeldung.com/java-inner-interfaces)
+- [Polymorphism in Java](http://www.baeldung.com/java-polymorphism)
+- [Recursion In Java](http://www.baeldung.com/java-recursion)
+- [A Guide to the finalize Method in Java](http://www.baeldung.com/java-finalize)

core-java/src/main/java/com/baeldung/finalize/CloseableResource.java

@@ -0,0 +1,30 @@
+package com.baeldung.finalize;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+
+public class CloseableResource implements AutoCloseable {
+    private BufferedReader reader;
+
+    public CloseableResource() {
+        InputStream input = this.getClass().getClassLoader().getResourceAsStream("file.txt");
+        reader = new BufferedReader(new InputStreamReader(input));
+    }
+
+    public String readFirstLine() throws IOException {
+        String firstLine = reader.readLine();
+        return firstLine;
+    }
+
+    @Override
+    public void close() {
+        try {
+            reader.close();
+            System.out.println("Closed BufferedReader in the close method");
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+}

core-java/src/main/java/com/baeldung/finalize/Finalizable.java

@@ -0,0 +1,30 @@
+package com.baeldung.finalize;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+
+public class Finalizable {
+    private BufferedReader reader;
+
+    public Finalizable() {
+        InputStream input = this.getClass().getClassLoader().getResourceAsStream("file.txt");
+        reader = new BufferedReader(new InputStreamReader(input));
+    }
+
+    public String readFirstLine() throws IOException {
+        String firstLine = reader.readLine();
+        return firstLine;
+    }
+
+    @Override
+    public void finalize() {
+        try {
+            reader.close();
+            System.out.println("Closed BufferedReader in the finalizer");
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+}

core-java/src/main/java/com/baeldung/trie/Trie.java

@@ -0,0 +1,62 @@
+package com.baeldung.trie;
+
+public class Trie {
+    private TrieNode root;
+
+    Trie() {
+        root = new TrieNode();
+    }
+
+    public void insert(String word) {
+        TrieNode current = root;
+
+        for (int i = 0; i < word.length(); i++) {
+            current = current.getChildren().computeIfAbsent(word.charAt(i), c -> new TrieNode());
+        }
+        current.setEndOfWord(true);
+    }
+
+    public boolean delete(String word) {
+        return delete(root, word, 0);
+    }
+
+    public boolean containsNode(String word) {
+        TrieNode current = root;
+
+        for (int i = 0; i < word.length(); i++) {
+            char ch = word.charAt(i);
+            TrieNode node = current.getChildren().get(ch);
+            if (node == null) {
+                return false;
+            }
+            current = node;
+        }
+        return current.isEndOfWord();
+    }
+
+    public boolean isEmpty() {
+        return root == null;
+    }
+
+    private boolean delete(TrieNode current, String word, int index) {
+        if (index == word.length()) {
+            if (!current.isEndOfWord()) {
+                return false;
+            }
+            current.setEndOfWord(false);
+            return current.getChildren().isEmpty();
+        }
+        char ch = word.charAt(index);
+        TrieNode node = current.getChildren().get(ch);
+        if (node == null) {
+            return false;
+        }
+        boolean shouldDeleteCurrentNode = delete(node, word, index + 1);
+
+        if (shouldDeleteCurrentNode) {
+            current.getChildren().remove(ch);
+            return current.getChildren().isEmpty();
+        }
+        return false;
+    }
+}

core-java/src/main/java/com/baeldung/trie/TrieNode.java

@@ -0,0 +1,31 @@
+package com.baeldung.trie;
+
+import java.util.HashMap;
+import java.util.Map;
+
+class TrieNode {
+    private Map<Character, TrieNode> children;
+    private boolean endOfWord;
+
+    public TrieNode() {
+        children = new HashMap<>();
+        endOfWord = false;
+    }
+
+    public Map<Character, TrieNode> getChildren() {
+        return children;
+    }
+
+    public void setChildren(Map<Character, TrieNode> children) {
+        this.children = children;
+    }
+
+    public boolean isEndOfWord() {
+        return endOfWord;
+    }
+
+    public void setEndOfWord(boolean endOfWord) {
+        this.endOfWord = endOfWord;
+    }
+
+}

core-java/src/test/java/com/baeldung/finalize/FinalizeUnitTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.finalize;
+
+import java.io.IOException;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class FinalizeUnitTest {
+    @Test
+    public void whenGC_thenFinalizerExecuted() throws IOException {
+        String firstLine = new Finalizable().readFirstLine();
+        Assert.assertEquals("baeldung.com", firstLine);
+        System.gc();
+    }
+
+    @Test
+    public void whenTryWResourcesExits_thenResourceClosed() throws IOException {
+        try (CloseableResource resource = new CloseableResource()) {
+            String firstLine = resource.readFirstLine();
+            Assert.assertEquals("baeldung.com", firstLine);
+        }
+    }
+}

core-java/src/test/java/com/baeldung/trie/TrieTest.java

@@ -0,0 +1,68 @@
+package com.baeldung.trie;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class TrieTest {
+
+    @Test
+    public void whenEmptyTrie_thenNoElements() {
+        Trie trie = new Trie();
+
+        assertFalse(trie.isEmpty());
+    }
+
+    @Test
+    public void givenATrie_whenAddingElements_thenTrieNotEmpty() {
+        Trie trie = createExampleTrie();
+
+        assertFalse(trie.isEmpty());
+    }
+
+    @Test
+    public void givenATrie_whenAddingElements_thenTrieHasThoseElements() {
+        Trie trie = createExampleTrie();
+
+        assertFalse(trie.containsNode("3"));
+        assertFalse(trie.containsNode("vida"));
+
+        assertTrue(trie.containsNode("Programming"));
+        assertTrue(trie.containsNode("is"));
+        assertTrue(trie.containsNode("a"));
+        assertTrue(trie.containsNode("way"));
+        assertTrue(trie.containsNode("of"));
+        assertTrue(trie.containsNode("life"));
+    }
+
+    @Test
+    public void givenATrie_whenLookingForNonExistingElement_thenReturnsFalse() {
+        Trie trie = createExampleTrie();
+
+        assertFalse(trie.containsNode("99"));
+    }
+
+    @Test
+    public void givenATrie_whenDeletingElements_thenTreeDoesNotContainThoseElements() {
+
+        Trie trie = createExampleTrie();
+
+        assertTrue(trie.containsNode("Programming"));
+        trie.delete("Programming");
+        assertFalse(trie.containsNode("Programming"));
+    }
+
+    private Trie createExampleTrie() {
+        Trie trie = new Trie();
+
+        trie.insert("Programming");
+        trie.insert("is");
+        trie.insert("a");
+        trie.insert("way");
+        trie.insert("of");
+        trie.insert("life");
+
+        return trie;
+    }
+}

core-kotlin/README.md

@@ -16,5 +16,5 @@
 - [Delegated Properties in Kotlin](http://www.baeldung.com/kotlin-delegated-properties)
 - [Sealed Classes in Kotlin](http://www.baeldung.com/kotlin-sealed-classes)
 - [JUnit 5 for Kotlin Developers](http://www.baeldung.com/junit-5-kotlin)
-
+- [Extension Methods in Kotlin](http://www.baeldung.com/kotlin-extension-methods)
 

core-kotlin/pom.xml

@@ -44,6 +44,16 @@
             <artifactId>kotlin-stdlib</artifactId>
             <version>${kotlin-stdlib.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib-jre8</artifactId>
+            <version>${kotlin-stdlib.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>khttp</groupId>
+            <artifactId>khttp</artifactId>
+            <version>0.1.0</version>
+        </dependency>
         <dependency>
             <groupId>org.jetbrains.kotlin</groupId>
             <artifactId>kotlin-test-junit</artifactId>

core-kotlin/src/test/kotlin/com/baeldung/kotlin/UseTest.kt

@@ -0,0 +1,67 @@
+package com.baeldung.kotlin
+
+import org.junit.Test
+import java.beans.ExceptionListener
+import java.beans.XMLEncoder
+import java.io.*
+import java.lang.Exception
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+import kotlin.test.fail
+
+class UseTest {
+
+    @Test
+    fun givenCloseable_whenUseIsCalled_thenItIsClosed() {
+        val stringWriter = StringWriter()
+        val writer = BufferedWriter(stringWriter) //Using a BufferedWriter because after close() it throws.
+        writer.use {
+            assertEquals(writer, it)
+
+            it.write("something")
+        }
+        try {
+            writer.write("something else")
+
+            fail("write() should have thrown an exception because the writer is closed.")
+        } catch (e: IOException) {
+            //Ok
+        }
+
+        assertEquals("something", stringWriter.toString())
+    }
+
+    @Test
+    fun givenAutoCloseable_whenUseIsCalled_thenItIsClosed() {
+        val baos = ByteArrayOutputStream()
+        val encoder = XMLEncoder(PrintStream(baos)) //XMLEncoder is AutoCloseable but not Closeable.
+                                                    //Here, we use a PrintStream because after close() it throws.
+        encoder.exceptionListener = ThrowingExceptionListener()
+        encoder.use {
+            assertEquals(encoder, it)
+
+            it.writeObject("something")
+        }
+        try {
+            encoder.writeObject("something else")
+            encoder.flush()
+
+            fail("write() should have thrown an exception because the encoder is closed.")
+        } catch (e: IOException) {
+            //Ok
+        }
+    }
+
+    @Test
+    fun whenSimpleFormIsUsed_thenItWorks() {
+        StringWriter().use { it.write("something") }
+    }
+}
+
+class ThrowingExceptionListener : ExceptionListener {
+    override fun exceptionThrown(e: Exception?) {
+        if(e != null) {
+            throw e
+        }
+    }
+}

core-kotlin/src/test/kotlin/com/baeldung/kotlin/khttp/KhttpTest.kt

@@ -0,0 +1,153 @@
+package com.baeldung.kotlin.khttp
+
+import khttp.structures.files.FileLike
+import org.json.JSONObject
+import org.junit.Test
+import java.beans.ExceptionListener
+import java.beans.XMLEncoder
+import java.io.*
+import java.lang.Exception
+import java.net.ConnectException
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+import kotlin.test.fail
+
+class KhttpTest {
+
+    @Test
+    fun whenHttpGetRequestIsMade_thenArgsAreReturned() {
+        val response = khttp.get(
+                url = "http://httpbin.org/get",
+                params = mapOf("p1" to "1", "p2" to "2"))
+        val args = response.jsonObject.getJSONObject("args")
+
+        assertEquals("1", args["p1"])
+        assertEquals("2", args["p2"])
+    }
+
+    @Test
+    fun whenAlternateHttpGetRequestIsMade_thenArgsAreReturned() {
+        val response = khttp.request(
+                method = "GET",
+                url = "http://httpbin.org/get",
+                params = mapOf("p1" to "1", "p2" to "2"))
+        val args = response.jsonObject.getJSONObject("args")
+
+        assertEquals("1", args["p1"])
+        assertEquals("2", args["p2"])
+    }
+
+    @Test
+    fun whenHeadersAreSet_thenHeadersAreSent() {
+        val response = khttp.get(
+                url = "http://httpbin.org/get",
+                headers = mapOf("header1" to "1", "header2" to "2"))
+        val headers = response.jsonObject.getJSONObject("headers")
+
+        assertEquals("1", headers["Header1"])
+        assertEquals("2", headers["Header2"])
+    }
+
+    @Test
+    fun whenHttpPostRequestIsMadeWithJson_thenBodyIsReturned() {
+        val response = khttp.post(
+                url = "http://httpbin.org/post",
+                params = mapOf("p1" to "1", "p2" to "2"),
+                json = mapOf("pr1" to "1", "pr2" to "2"))
+
+        val args = response.jsonObject.getJSONObject("args")
+
+        assertEquals("1", args["p1"])
+        assertEquals("2", args["p2"])
+
+        val json = response.jsonObject.getJSONObject("json")
+
+        assertEquals("1", json["pr1"])
+        assertEquals("2", json["pr2"])
+    }
+
+    @Test
+    fun whenHttpPostRequestIsMadeWithMapData_thenBodyIsReturned() {
+        val response = khttp.post(
+                url = "http://httpbin.org/post",
+                params = mapOf("p1" to "1", "p2" to "2"),
+                data = mapOf("pr1" to "1", "pr2" to "2"))
+
+        val args = response.jsonObject.getJSONObject("args")
+
+        assertEquals("1", args["p1"])
+        assertEquals("2", args["p2"])
+
+        val form = response.jsonObject.getJSONObject("form")
+
+        assertEquals("1", form["pr1"])
+        assertEquals("2", form["pr2"])
+    }
+
+    @Test
+    fun whenHttpPostRequestIsMadeWithFiles_thenBodyIsReturned() {
+        val response = khttp.post(
+                url = "http://httpbin.org/post",
+                params = mapOf("p1" to "1", "p2" to "2"),
+                files = listOf(
+                        FileLike("file1", "content1"),
+                        FileLike("file2", javaClass.getResource("KhttpTest.class").openStream().readBytes())))
+
+        val args = response.jsonObject.getJSONObject("args")
+
+        assertEquals("1", args["p1"])
+        assertEquals("2", args["p2"])
+
+        val files = response.jsonObject.getJSONObject("files")
+
+        assertEquals("content1", files["file1"])
+    }
+
+    @Test
+    fun whenHttpPostRequestIsMadeWithInputStream_thenBodyIsReturned() {
+        val response = khttp.post(
+                url = "http://httpbin.org/post",
+                params = mapOf("p1" to "1", "p2" to "2"),
+                data = ByteArrayInputStream("content!".toByteArray()))
+
+        val args = response.jsonObject.getJSONObject("args")
+
+        assertEquals("1", args["p1"])
+        assertEquals("2", args["p2"])
+
+        assertEquals("content!", response.jsonObject["data"])
+    }
+
+    @Test
+    fun whenHttpPostStreamingRequestIsMade_thenBodyIsReturnedInChunks() {
+        val response = khttp.post(
+                url = "http://httpbin.org/post",
+                stream = true,
+                json = mapOf("pr1" to "1", "pr2" to "2"))
+
+        val baos = ByteArrayOutputStream()
+        response.contentIterator(chunkSize = 10).forEach { arr : ByteArray -> baos.write(arr) }
+        val json = JSONObject(String(baos.toByteArray())).getJSONObject("json")
+
+        assertEquals("1", json["pr1"])
+        assertEquals("2", json["pr2"])
+    }
+
+    @Test
+    fun whenHttpRequestFails_thenExceptionIsThrown() {
+        try {
+            khttp.get(url = "http://localhost/nothing/to/see/here")
+
+            fail("Should have thrown an exception")
+        } catch (e : ConnectException) {
+            //Ok
+        }
+    }
+
+    @Test
+    fun whenHttpNotFound_thenExceptionIsThrown() {
+        val response = khttp.get(url = "http://httpbin.org/nothing/to/see/here")
+
+        assertEquals(404, response.statusCode)
+    }
+}