Merge pull request #1 from eugenp/master

Update - 20191227

akka-http/pom.xml

@@ -0,0 +1,48 @@
+<?xml version="1.0"?>
+<project
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"
+	xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
+
+	<modelVersion>4.0.0</modelVersion>
+	<artifactId>akka-http</artifactId>
+	<name>akka-http</name>
+
+	<parent>
+		<artifactId>parent-modules</artifactId>
+		<groupId>com.baeldung</groupId>
+		<version>1.0.0-SNAPSHOT</version>
+	</parent>
+
+	<dependencies>
+		<dependency>
+			<groupId>com.typesafe.akka</groupId>
+			<artifactId>akka-http_2.12</artifactId>
+			<version>${akka.http.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>com.typesafe.akka</groupId>
+			<artifactId>akka-stream_2.12</artifactId>
+			<version>2.5.11</version>
+		</dependency>
+		<dependency>
+			<groupId>com.typesafe.akka</groupId>
+			<artifactId>akka-http-jackson_2.12</artifactId>
+			<version>${akka.http.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>com.typesafe.akka</groupId>
+			<artifactId>akka-http-testkit_2.12</artifactId>
+			<version>${akka.http.version}</version>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
+
+	<properties>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+		<java.version>1.8</java.version>
+		<akka.http.version>10.0.11</akka.http.version>
+		<akka.stream.version>2.5.11</akka.stream.version>
+	</properties>
+</project>

akka-http/src/main/java/com/baeldung/akkahttp/User.java

@@ -0,0 +1,26 @@
+package com.baeldung.akkahttp;
+
+public class User {
+
+    private final Long id;
+
+    private final String name;
+
+    public User() {
+        this.name = "";
+        this.id = null;
+    }
+
+    public User(Long id, String name) {
+        this.name = name;
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public Long getId() {
+        return id;
+    }
+}

akka-http/src/main/java/com/baeldung/akkahttp/UserActor.java

@@ -0,0 +1,41 @@
+package com.baeldung.akkahttp;
+
+import akka.actor.AbstractActor;
+import akka.actor.Props;
+import akka.japi.pf.FI;
+import com.baeldung.akkahttp.UserMessages.ActionPerformed;
+import com.baeldung.akkahttp.UserMessages.CreateUserMessage;
+import com.baeldung.akkahttp.UserMessages.GetUserMessage;
+
+
+class UserActor extends AbstractActor {
+
+  private UserService userService = new UserService();
+
+  static Props props() {
+    return Props.create(UserActor.class);
+  }
+
+  @Override
+  public Receive createReceive() {
+    return receiveBuilder()
+            .match(CreateUserMessage.class, handleCreateUser())
+            .match(GetUserMessage.class, handleGetUser())
+            .build();
+  }
+
+  private FI.UnitApply<CreateUserMessage> handleCreateUser() {
+    return createUserMessageMessage -> {
+      userService.createUser(createUserMessageMessage.getUser());
+      sender().tell(new ActionPerformed(String.format("User %s created.", createUserMessageMessage.getUser()
+              .getName())), getSelf());
+    };
+  }
+
+  private FI.UnitApply<GetUserMessage> handleGetUser() {
+    return getUserMessageMessage -> {
+      sender().tell(userService.getUser(getUserMessageMessage.getUserId()), getSelf());
+    };
+  }
+
+}

akka-http/src/main/java/com/baeldung/akkahttp/UserMessages.java

@@ -0,0 +1,49 @@
+package com.baeldung.akkahttp;
+
+import java.io.Serializable;
+
+public interface UserMessages {
+
+  class ActionPerformed implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    private final String description;
+
+    public ActionPerformed(String description) {
+      this.description = description;
+    }
+
+    public String getDescription() {
+      return description;
+    }
+  }
+
+  class CreateUserMessage implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+    private final User user;
+
+    public CreateUserMessage(User user) {
+      this.user = user;
+    }
+
+    public User getUser() {
+      return user;
+    }
+  }
+
+  class GetUserMessage implements Serializable {
+    private static final long serialVersionUID = 1L;
+    private final Long userId;
+
+    public GetUserMessage(Long userId) {
+      this.userId = userId;
+    }
+
+    public Long getUserId() {
+      return userId;
+    }
+  }
+
+}

akka-http/src/main/java/com/baeldung/akkahttp/UserServer.java

@@ -0,0 +1,70 @@
+package com.baeldung.akkahttp;
+
+import java.util.Optional;
+import java.util.concurrent.CompletionStage;
+import java.util.concurrent.TimeUnit;
+
+import akka.actor.ActorRef;
+import akka.actor.ActorSystem;
+import akka.http.javadsl.marshallers.jackson.Jackson;
+import akka.http.javadsl.model.StatusCodes;
+import akka.http.javadsl.server.HttpApp;
+import akka.http.javadsl.server.Route;
+import akka.pattern.PatternsCS;
+import akka.util.Timeout;
+import com.baeldung.akkahttp.UserMessages.ActionPerformed;
+import com.baeldung.akkahttp.UserMessages.CreateUserMessage;
+import com.baeldung.akkahttp.UserMessages.GetUserMessage;
+import scala.concurrent.duration.Duration;
+import static akka.http.javadsl.server.PathMatchers.*;
+
+class UserServer extends HttpApp {
+
+  private final ActorRef userActor;
+
+  Timeout timeout = new Timeout(Duration.create(5, TimeUnit.SECONDS));
+
+  UserServer(ActorRef userActor) {
+    this.userActor = userActor;
+  }
+
+  @Override
+  public Route routes() {
+    return path("users", this::postUser)
+            .orElse(path(segment("users").slash(longSegment()), id ->
+                    route(getUser(id))));
+  }
+
+  private Route getUser(Long id) {
+    return get(() -> {
+      CompletionStage<Optional<User>> user = PatternsCS.ask(userActor, new GetUserMessage(id), timeout)
+              .thenApply(obj -> (Optional<User>) obj);
+
+      return onSuccess(() -> user, performed -> {
+        if (performed.isPresent())
+          return complete(StatusCodes.OK, performed.get(), Jackson.marshaller());
+        else
+          return complete(StatusCodes.NOT_FOUND);
+      });
+    });
+  }
+
+  private Route postUser() {
+    return route(post(() -> entity(Jackson.unmarshaller(User.class), user -> {
+      CompletionStage<ActionPerformed> userCreated = PatternsCS.ask(userActor, new CreateUserMessage(user), timeout)
+              .thenApply(obj -> (ActionPerformed) obj);
+
+      return onSuccess(() -> userCreated, performed -> {
+        return complete(StatusCodes.CREATED, performed, Jackson.marshaller());
+      });
+    })));
+  }
+
+  public static void main(String[] args) throws Exception {
+    ActorSystem system = ActorSystem.create("userServer");
+    ActorRef userActor = system.actorOf(UserActor.props(), "userActor");
+    UserServer server = new UserServer(userActor);
+    server.startServer("localhost", 8080, system);
+  }
+
+}

akka-http/src/main/java/com/baeldung/akkahttp/UserService.java

@@ -0,0 +1,35 @@
+package com.baeldung.akkahttp;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+
+public class UserService {
+
+  private final static List<User> users = new ArrayList<>();
+
+  static {
+    users.add(new User(1l, "Alice"));
+    users.add(new User(2l, "Bob"));
+    users.add(new User(3l, "Chris"));
+    users.add(new User(4l, "Dick"));
+    users.add(new User(5l, "Eve"));
+    users.add(new User(6l, "Finn"));
+  }
+
+  public Optional<User> getUser(Long id) {
+    return users.stream()
+            .filter(user -> user.getId()
+                    .equals(id))
+            .findFirst();
+  }
+
+  public void createUser(User user) {
+    users.add(user);
+  }
+
+  public List<User> getUsers(){
+    return users;
+  }
+
+}

akka-http/src/test/java/com/baeldung/akkahttp/UserServerUnitTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.akkahttp;
+
+import akka.actor.ActorRef;
+import akka.actor.ActorSystem;
+import akka.http.javadsl.model.ContentTypes;
+import akka.http.javadsl.model.HttpEntities;
+import akka.http.javadsl.model.HttpRequest;
+import akka.http.javadsl.testkit.JUnitRouteTest;
+import akka.http.javadsl.testkit.TestRoute;
+import org.junit.Test;
+
+public class UserServerUnitTest extends JUnitRouteTest {
+
+  ActorSystem system = ActorSystem.create("helloAkkaHttpServer");
+
+  ActorRef userActorRef = system.actorOf(UserActor.props(), "userActor");
+
+  TestRoute appRoute = testRoute(new UserServer(userActorRef).routes());
+
+  @Test
+  public void whenRequest_thenActorResponds() {
+
+    appRoute.run(HttpRequest.GET("/users/1"))
+            .assertEntity(alice())
+            .assertStatusCode(200);
+
+    appRoute.run(HttpRequest.GET("/users/42"))
+            .assertStatusCode(404);
+
+    appRoute.run(HttpRequest.DELETE("/users/1"))
+            .assertStatusCode(200);
+
+    appRoute.run(HttpRequest.DELETE("/users/42"))
+            .assertStatusCode(200);
+
+    appRoute.run(HttpRequest.POST("/users")
+            .withEntity(HttpEntities.create(ContentTypes.APPLICATION_JSON, zaphod())))
+            .assertStatusCode(201);
+
+  }
+
+  private String alice() {
+    return "{\"id\":1,\"name\":\"Alice\"}";
+  }
+
+  private String zaphod() {
+    return "{\"id\":42,\"name\":\"Zaphod\"}";
+  }
+
+}

algorithms-miscellaneous-1/README.md

@@ -10,4 +10,6 @@
 - [Multi-Swarm Optimization Algorithm in Java](http://www.baeldung.com/java-multi-swarm-algorithm)
 - [String Search Algorithms for Large Texts](http://www.baeldung.com/java-full-text-search-algorithms)
 - [Check If a String Contains All The Letters of The Alphabet](https://www.baeldung.com/java-string-contains-all-letters)
-- [Find the Middle Element of a Linked List](http://www.baeldung.com/java-linked-list-middle-element)
+- [Find the Middle Element of a Linked List](http://www.baeldung.com/java-linked-list-middle-element)
+- [Calculate Factorial in Java](https://www.baeldung.com/java-calculate-factorial)
+- [Find Substrings That Are Palindromes in Java](https://www.baeldung.com/java-palindrome-substrings)

algorithms-miscellaneous-1/src/main/java/com/baeldung/algorithms/string/SubstringPalindrome.java

@@ -1,4 +1,4 @@
-package com.baeldung.string;
+package com.baeldung.algorithms.string;
 
 import java.util.HashSet;
 import java.util.Set;

algorithms-miscellaneous-1/src/test/java/com/baeldung/algorithms/string/SubstringPalindromeUnitTest.java

@@ -1,4 +1,4 @@
-package com.baeldung.string;
+package com.baeldung.algorithms.string;
 
 import static org.junit.Assert.assertEquals;
 import java.util.HashSet;

algorithms-sorting/src/main/java/com/baeldung/algorithms/mergesort/MergeSort.java

@@ -34,7 +34,7 @@ public class MergeSort {
 
         while (i < left && j < right) {
 
-            if (l[i] < r[j])
+            if (l[i] <= r[j])
                 a[k++] = l[i++];
             else
                 a[k++] = r[j++];

apache-curator/pom.xml

@@ -59,7 +59,7 @@
     <properties>
         <curator.version>4.0.1</curator.version>
         <zookeeper.version>3.4.11</zookeeper.version>
-        <jackson-databind.version>2.9.4</jackson-databind.version>
+        <jackson-databind.version>2.9.7</jackson-databind.version>
         <!-- testing -->
         <assertj.version>3.6.1</assertj.version>
         <avaitility.version>1.7.0</avaitility.version>

core-java-11/README.md

@@ -0,0 +1,5 @@
+### Relevant articles
+
+- [Java 11 Single File Source Code](https://www.baeldung.com/java-single-file-source-code)
+- [Java 11 Local Variable Syntax for Lambda Parameters](https://www.baeldung.com/java-var-lambda-params)
+

core-java-11/src/main/java/com/baeldung/add

@@ -0,0 +1,12 @@
+#!/usr/local/bin/java --source 11
+
+import java.util.Arrays;
+
+public class Addition
+{
+    public static void main(String[] args) {
+        System.out.println(Arrays.stream(args)
+          .mapToInt(Integer::parseInt)
+          .sum());
+    }
+}

core-java-11/src/test/java/com/baeldung/NewStringAPIUnitTest.java

@@ -0,0 +1,43 @@
+package com.baeldung;
+
+import static org.hamcrest.CoreMatchers.is;
+
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+public class NewStringAPIUnitTest {
+
+    @Test
+    public void whenRepeatStringTwice_thenGetStringTwice() {
+        String output = "La ".repeat(2) + "Land";
+
+        is(output).equals("La La Land");
+    }
+
+    @Test
+    public void whenStripString_thenReturnStringWithoutWhitespaces() {
+        is("\n\t  hello   \u2005".strip()).equals("hello");
+    }
+
+    @Test
+    public void whenTrimAdvanceString_thenReturnStringWithWhitespaces() {
+        is("\n\t  hello   \u2005".trim()).equals("hello   \u2005");
+    }
+
+    @Test
+    public void whenBlankString_thenReturnTrue() {
+        assertTrue("\n\t\u2005  ".isBlank());
+    }
+
+    @Test
+    public void whenMultilineString_thenReturnNonEmptyLineCount() {
+        String multilineStr = "This is\n \n a multiline\n string.";
+
+        long lineCount = multilineStr.lines()
+          .filter(String::isBlank)
+          .count();
+
+        is(lineCount).equals(3L);
+    }
+}

core-java-8/README.md

@@ -15,7 +15,6 @@
 - [Guide to Java 8 Comparator.comparing()](http://www.baeldung.com/java-8-comparator-comparing)
 - [Guide To Java 8 Optional](http://www.baeldung.com/java-optional)
 - [Guide to the Java 8 forEach](http://www.baeldung.com/foreach-java)
-- [Java Base64 Encoding and Decoding](http://www.baeldung.com/java-base64-encode-and-decode)
 - [The Difference Between map() and flatMap()](http://www.baeldung.com/java-difference-map-and-flatmap)
 - [Static and Default Methods in Interfaces in Java](http://www.baeldung.com/java-static-default-methods)
 - [Efficient Word Frequency Calculator in Java](http://www.baeldung.com/java-word-frequency)

core-java-8/src/main/java/com/baeldung/interfaces/Electronic.java

@@ -0,0 +1,22 @@
+package com.baeldung.interfaces;
+
+public interface Electronic {
+    //Constant variable
+    public static final String LED = "LED";
+
+    //Abstract method
+    public int getElectricityUse();
+
+    // Static method
+    public static boolean isEnergyEfficient(String electtronicType) {
+        if (electtronicType.equals(LED)) {
+            return true;
+        }
+        return false;
+    }
+
+    //Default method
+    public default void printDescription() {
+        System.out.println("Electronic Description");
+    }
+}

core-java-8/src/main/java/com/baeldung/interfaces/Employee.java

@@ -0,0 +1,15 @@
+package com.baeldung.interfaces;
+
+public class Employee {
+
+    private double salary;
+
+    public double getSalary() {
+        return salary;
+    }
+
+    public void setSalary(double salary) {
+        this.salary = salary;
+    }
+
+}

core-java-8/src/main/java/com/baeldung/interfaces/EmployeeSalaryComparator.java

@@ -0,0 +1,18 @@
+package com.baeldung.interfaces;
+
+import java.util.Comparator;
+
+public class EmployeeSalaryComparator implements Comparator<Employee> {
+
+    @Override
+    public int compare(Employee employeeA, Employee employeeB) {
+
+        if(employeeA.getSalary() < employeeB.getSalary()){
+            return -1;
+        }else if(employeeA.getSalary() > employeeB.getSalary()){
+            return 1;
+        }else{
+            return 0;
+        }
+    }
+}

core-java-8/src/main/java/com/baeldung/interfaces/HasColor.java

@@ -0,0 +1,5 @@
+package com.baeldung.interfaces;
+
+public interface HasColor {
+    public String getColor();
+}

core-java-8/src/main/java/com/baeldung/interfaces/Motorcycle.java

@@ -0,0 +1,10 @@
+package com.baeldung.interfaces;
+
+import com.baeldung.interfaces.multiinheritance.Transform;
+
+public class Motorcycle implements Transform {
+    @Override
+    public void transform() {
+        // Implementation
+    }
+}

core-java-8/src/main/java/com/baeldung/interfaces/Truck.java

@@ -0,0 +1,8 @@
+package com.baeldung.interfaces;
+
+public class Truck extends Vehicle {
+    @Override
+    public void transform() {
+        // implementation
+    }
+}

core-java-8/src/main/java/com/baeldung/interfaces/Vehicle.java

@@ -0,0 +1,6 @@
+package com.baeldung.interfaces;
+
+import com.baeldung.interfaces.multiinheritance.Transform;
+
+public abstract class Vehicle implements Transform {
+}

core-java-8/src/main/java/com/baeldung/interfaces/multiinheritance/Car.java

@@ -0,0 +1,13 @@
+package com.baeldung.interfaces.multiinheritance;
+
+public class Car implements Fly, Transform {
+    @Override
+    public void fly() {
+        System.out.println("I can Fly!!");
+    }
+
+    @Override
+    public void transform() {
+        System.out.println("I can Transform!!");
+    }
+}

core-java-8/src/main/java/com/baeldung/interfaces/multiinheritance/Fly.java

@@ -0,0 +1,5 @@
+package com.baeldung.interfaces.multiinheritance;
+
+public abstract interface Fly{
+    void fly();
+}

core-java-8/src/main/java/com/baeldung/interfaces/multiinheritance/Transform.java

@@ -0,0 +1,10 @@
+package com.baeldung.interfaces.multiinheritance;
+
+public interface Transform {
+
+    void transform();
+
+    default void printSpecs(){
+        System.out.println("Transform Specification");
+    }
+}

core-java-8/src/main/java/com/baeldung/interfaces/multiinheritance/Vehicle.java

@@ -0,0 +1,13 @@
+package com.baeldung.interfaces.multiinheritance;
+
+public class Vehicle implements Fly, Transform {
+    @Override
+    public void fly() {
+        System.out.println("I can Fly!!");
+    }
+
+    @Override
+    public void transform() {
+        System.out.println("I can Transform!!");
+    }
+}

core-java-8/src/main/java/com/baeldung/interfaces/polymorphysim/Circle.java

@@ -0,0 +1,25 @@
+package com.baeldung.interfaces.polymorphysim;
+
+public class Circle implements Shape {
+
+    private double radius;
+
+    public Circle(double radius){
+        this.radius = radius;
+    }
+
+    @Override
+    public String name() {
+        return "Circle";
+    }
+
+    @Override
+    public double area() {
+        return Math.PI * (radius * radius);
+    }
+
+    @Override
+    public String getColor() {
+        return "green";
+    }
+}

core-java-8/src/main/java/com/baeldung/interfaces/polymorphysim/DisplayShape.java

@@ -0,0 +1,26 @@
+package com.baeldung.interfaces.polymorphysim;
+
+import java.util.ArrayList;
+
+public class DisplayShape {
+
+    private ArrayList<Shape> shapes;
+
+    public ArrayList<Shape> getShapes() {
+        return shapes;
+    }
+
+    public DisplayShape() {
+        shapes = new ArrayList<>();
+    }
+
+    public void add(Shape shape) {
+        shapes.add(shape);
+    }
+
+    public void display() {
+        for (Shape shape : shapes) {
+            System.out.println(shape.name() + " area: " + shape.area());
+        }
+    }
+}

core-java-8/src/main/java/com/baeldung/interfaces/polymorphysim/FunctionalMain.java

@@ -0,0 +1,23 @@
+package com.baeldung.interfaces.polymorphysim;
+
+import java.util.function.Predicate;
+
+public class FunctionalMain {
+
+public static void main(String[] args) {
+    Shape circleShape = new Circle(2);
+    Shape squareShape = new Square(2);
+
+    DisplayShape DisplayShape = new DisplayShape();
+    DisplayShape.add(circleShape);
+    DisplayShape.add(squareShape);
+
+    Predicate<Shape> checkArea = (shape) -> shape.area() < 5;
+
+    for (Shape shape : DisplayShape.getShapes()) {
+        if (checkArea.test(shape)) {
+            System.out.println(shape.name() + " " + shape.area());
+        }
+    }
+}
+}