Merge branch 'master' into BAEL-1556

2018-03-26 14:34:27 +02:00
parent 94421b7d38 01ff4b53ab
commit af3141d412
1002 changed files with 34744 additions and 4119 deletions
@@ -4,7 +4,7 @@ before_install:
  - echo "MAVEN_OPTS='-Xmx2048M -Xss128M -XX:+CMSClassUnloadingEnabled -XX:+UseG1GC -XX:-UseGCOverheadLimit'" > ~/.mavenrc

 install: skip
-script: travis_wait 60 mvn -q test -fae
+script: travis_wait 60 mvn -q test

 sudo: required

@@ -16,3 +16,4 @@
 - [Introduction to Minimax Algorithm](http://www.baeldung.com/java-minimax-algorithm)
 - [How to Calculate Levenshtein Distance in Java?](http://www.baeldung.com/java-levenshtein-distance)
 - [How to Find the Kth Largest Element in Java](http://www.baeldung.com/java-kth-largest-element)
+- [Multi-Swarm Optimization Algorithm in Java](http://www.baeldung.com/java-multi-swarm-algorithm)
@@ -9,6 +9,7 @@
        <exec-maven-plugin.version>1.5.0</exec-maven-plugin.version>
        <lombok.version>1.16.12</lombok.version>
        <commons-math3.version>3.6.1</commons-math3.version>
+        <tradukisto.version>1.0.1</tradukisto.version>
    </properties>

    <parent>
@@ -39,6 +40,11 @@
            <artifactId>jgrapht-core</artifactId>
            <version>1.0.1</version>
        </dependency>
+        <dependency>
+            <groupId>pl.allegro.finance</groupId>
+            <artifactId>tradukisto</artifactId>
+            <version>${tradukisto.version}</version>
+        </dependency>
        <dependency>
            <groupId>org.assertj</groupId>
            <artifactId>assertj-core</artifactId>
@@ -46,7 +52,6 @@
            <scope>test</scope>
        </dependency>
    </dependencies>
-
    <build>
        <pluginManagement>
            <plugins>
@@ -77,4 +82,4 @@
            </plugin>
        </plugins>
    </reporting>
-</project>
+</project>
@@ -0,0 +1,47 @@
+package com.baeldung.algorithms.multiswarm;
+
+/**
+ * Constants used by the Multi-swarm optimization algorithms.
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public class Constants {
+
+	/**
+	 * The inertia factor encourages a particle to continue moving in its
+	 * current direction.
+	 */
+	public static final double INERTIA_FACTOR = 0.729;
+
+	/**
+	 * The cognitive weight encourages a particle to move toward its historical
+	 * best-known position.
+	 */
+	public static final double COGNITIVE_WEIGHT = 1.49445;
+
+	/**
+	 * The social weight encourages a particle to move toward the best-known
+	 * position found by any of the particle’s swarm-mates.
+	 */
+	public static final double SOCIAL_WEIGHT = 1.49445;
+
+	/**
+	 * The global weight encourages a particle to move toward the best-known
+	 * position found by any particle in any swarm.
+	 */
+	public static final double GLOBAL_WEIGHT = 0.3645;
+
+	/**
+	 * Upper bound for the random generation. We use it to reduce the
+	 * computation time since we can rawly estimate it.
+	 */
+	public static final int PARTICLE_UPPER_BOUND = 10000000;
+
+	/**
+	 * Private constructor for utility class.
+	 */
+	private Constants() {
+	}
+
+}
@@ -0,0 +1,21 @@
+package com.baeldung.algorithms.multiswarm;
+
+/**
+ * Interface for a fitness function, used to decouple the main algorithm logic
+ * from the specific problem solution.
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public interface FitnessFunction {
+
+	/**
+	 * Returns the fitness of a particle given its position.
+	 * 
+	 * @param particlePosition
+	 *            the position of the particle
+	 * @return the fitness of the particle
+	 */
+	public double getFitness(long[] particlePosition);
+
+}
@@ -0,0 +1,227 @@
+package com.baeldung.algorithms.multiswarm;
+
+import java.util.Arrays;
+import java.util.Random;
+
+/**
+ * Represents a collection of {@link Swarm}.
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public class Multiswarm {
+
+	/**
+	 * The swarms managed by this multiswarm.
+	 */
+	private Swarm[] swarms;
+
+	/**
+	 * The best position found within all the {@link #swarms}.
+	 */
+	private long[] bestPosition;
+
+	/**
+	 * The best fitness score found within all the {@link #swarms}.
+	 */
+	private double bestFitness = Double.NEGATIVE_INFINITY;
+
+	/**
+	 * A random generator.
+	 */
+	private Random random = new Random();
+
+	/**
+	 * The fitness function used to determine how good is a particle.
+	 */
+	private FitnessFunction fitnessFunction;
+
+	/**
+	 * Instantiates a new Multiswarm.
+	 * 
+	 * @param numSwarms
+	 *            the number of {@link #swarms}
+	 * @param particlesPerSwarm
+	 *            the number of particle for each {@link #swarms}
+	 * @param fitnessFunction
+	 *            the {@link #fitnessFunction}
+	 */
+	public Multiswarm(int numSwarms, int particlesPerSwarm, FitnessFunction fitnessFunction) {
+		this.fitnessFunction = fitnessFunction;
+		this.swarms = new Swarm[numSwarms];
+		for (int i = 0; i < numSwarms; i++) {
+			swarms[i] = new Swarm(particlesPerSwarm);
+		}
+	}
+
+	/**
+	 * Main loop of the algorithm. Iterates all particles of all
+	 * {@link #swarms}. For each particle, computes the new fitness and checks
+	 * if a new best position has been found among itself, the swarm and all the
+	 * swarms and finally updates the particle position and speed.
+	 */
+	public void mainLoop() {
+		for (Swarm swarm : swarms) {
+			for (Particle particle : swarm.getParticles()) {
+
+				long[] particleOldPosition = particle.getPosition().clone();
+
+				// Calculate the particle fitness.
+				particle.setFitness(fitnessFunction.getFitness(particleOldPosition));
+
+				// Check if a new best position has been found for the particle
+				// itself, within the swarm and the multiswarm.
+				if (particle.getFitness() > particle.getBestFitness()) {
+					particle.setBestFitness(particle.getFitness());
+					particle.setBestPosition(particleOldPosition);
+
+					if (particle.getFitness() > swarm.getBestFitness()) {
+						swarm.setBestFitness(particle.getFitness());
+						swarm.setBestPosition(particleOldPosition);
+
+						if (swarm.getBestFitness() > bestFitness) {
+							bestFitness = swarm.getBestFitness();
+							bestPosition = swarm.getBestPosition().clone();
+						}
+
+					}
+				}
+
+				// Updates the particle position by adding the speed to the
+				// actual position.
+				long[] position = particle.getPosition();
+				long[] speed = particle.getSpeed();
+
+				position[0] += speed[0];
+				position[1] += speed[1];
+
+				// Updates the particle speed.
+				speed[0] = getNewParticleSpeedForIndex(particle, swarm, 0);
+				speed[1] = getNewParticleSpeedForIndex(particle, swarm, 1);
+			}
+		}
+	}
+
+	/**
+	 * Computes a new speed for a given particle of a given swarm on a given
+	 * axis. The new speed is computed using the formula:
+	 * 
+	 * <pre>
+	 * ({@link Constants#INERTIA_FACTOR} * {@link Particle#getSpeed()}) + 
+	 * (({@link Constants#COGNITIVE_WEIGHT} * random(0,1)) * ({@link Particle#getBestPosition()} - {@link Particle#getPosition()})) +
+	 * (({@link Constants#SOCIAL_WEIGHT} * random(0,1)) * ({@link Swarm#getBestPosition()} - {@link Particle#getPosition()})) + 
+	 * (({@link Constants#GLOBAL_WEIGHT} * random(0,1)) * ({@link #bestPosition} - {@link Particle#getPosition()}))
+	 * </pre>
+	 *
+	 * @param particle
+	 *            the particle whose new speed needs to be computed
+	 * @param swarm
+	 *            the swarm which contains the particle
+	 * @param index
+	 *            the index of the particle axis whose speeds needs to be
+	 *            computed
+	 * @return the new speed of the particle passed on the given axis
+	 */
+	private int getNewParticleSpeedForIndex(Particle particle, Swarm swarm, int index) {
+		return (int) ((Constants.INERTIA_FACTOR * particle.getSpeed()[index])
+				+ (randomizePercentage(Constants.COGNITIVE_WEIGHT)
+						* (particle.getBestPosition()[index] - particle.getPosition()[index]))
+				+ (randomizePercentage(Constants.SOCIAL_WEIGHT)
+						* (swarm.getBestPosition()[index] - particle.getPosition()[index]))
+				+ (randomizePercentage(Constants.GLOBAL_WEIGHT)
+						* (bestPosition[index] - particle.getPosition()[index])));
+	}
+
+	/**
+	 * Returns a random number between 0 and the value passed as argument.
+	 *
+	 * @param value
+	 *            the value to randomize
+	 * @return a random value between 0 and the one passed as argument
+	 */
+	private double randomizePercentage(double value) {
+		return random.nextDouble() * value;
+	}
+
+	/**
+	 * Gets the {@link #bestPosition}.
+	 *
+	 * @return the {@link #bestPosition}
+	 */
+	public long[] getBestPosition() {
+		return bestPosition;
+	}
+
+	/**
+	 * Gets the {@link #bestFitness}.
+	 *
+	 * @return the {@link #bestFitness}
+	 */
+	public double getBestFitness() {
+		return bestFitness;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#hashCode()
+	 */
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		long temp;
+		temp = Double.doubleToLongBits(bestFitness);
+		result = prime * result + (int) (temp ^ (temp >>> 32));
+		result = prime * result + Arrays.hashCode(bestPosition);
+		result = prime * result + ((fitnessFunction == null) ? 0 : fitnessFunction.hashCode());
+		result = prime * result + ((random == null) ? 0 : random.hashCode());
+		result = prime * result + Arrays.hashCode(swarms);
+		return result;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#equals(java.lang.Object)
+	 */
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		Multiswarm other = (Multiswarm) obj;
+		if (Double.doubleToLongBits(bestFitness) != Double.doubleToLongBits(other.bestFitness))
+			return false;
+		if (!Arrays.equals(bestPosition, other.bestPosition))
+			return false;
+		if (fitnessFunction == null) {
+			if (other.fitnessFunction != null)
+				return false;
+		} else if (!fitnessFunction.equals(other.fitnessFunction))
+			return false;
+		if (random == null) {
+			if (other.random != null)
+				return false;
+		} else if (!random.equals(other.random))
+			return false;
+		if (!Arrays.equals(swarms, other.swarms))
+			return false;
+		return true;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#toString()
+	 */
+	@Override
+	public String toString() {
+		return "Multiswarm [swarms=" + Arrays.toString(swarms) + ", bestPosition=" + Arrays.toString(bestPosition)
+				+ ", bestFitness=" + bestFitness + ", random=" + random + ", fitnessFunction=" + fitnessFunction + "]";
+	}
+
+}
@@ -0,0 +1,204 @@
+package com.baeldung.algorithms.multiswarm;
+
+import java.util.Arrays;
+
+/**
+ * Represents a particle, the basic component of a {@link Swarm}.
+ * 
+ * @author Donato Rimenti
+ * 
+ */
+public class Particle {
+
+	/**
+	 * The current position of this particle.
+	 */
+	private long[] position;
+
+	/**
+	 * The speed of this particle.
+	 */
+	private long[] speed;
+
+	/**
+	 * The fitness of this particle for the current position.
+	 */
+	private double fitness;
+
+	/**
+	 * The best position found by this particle.
+	 */
+	private long[] bestPosition;
+
+	/**
+	 * The best fitness found by this particle.
+	 */
+	private double bestFitness = Double.NEGATIVE_INFINITY;
+
+	/**
+	 * Instantiates a new Particle.
+	 *
+	 * @param initialPosition
+	 *            the initial {@link #position}
+	 * @param initialSpeed
+	 *            the initial {@link #speed}
+	 */
+	public Particle(long[] initialPosition, long[] initialSpeed) {
+		this.position = initialPosition;
+		this.speed = initialSpeed;
+	}
+
+	/**
+	 * Gets the {@link #position}.
+	 *
+	 * @return the {@link #position}
+	 */
+	public long[] getPosition() {
+		return position;
+	}
+
+	/**
+	 * Gets the {@link #speed}.
+	 *
+	 * @return the {@link #speed}
+	 */
+	public long[] getSpeed() {
+		return speed;
+	}
+
+	/**
+	 * Gets the {@link #fitness}.
+	 *
+	 * @return the {@link #fitness}
+	 */
+	public double getFitness() {
+		return fitness;
+	}
+
+	/**
+	 * Gets the {@link #bestPosition}.
+	 *
+	 * @return the {@link #bestPosition}
+	 */
+	public long[] getBestPosition() {
+		return bestPosition;
+	}
+
+	/**
+	 * Gets the {@link #bestFitness}.
+	 *
+	 * @return the {@link #bestFitness}
+	 */
+	public double getBestFitness() {
+		return bestFitness;
+	}
+
+	/**
+	 * Sets the {@link #position}.
+	 *
+	 * @param position
+	 *            the new {@link #position}
+	 */
+	public void setPosition(long[] position) {
+		this.position = position;
+	}
+
+	/**
+	 * Sets the {@link #speed}.
+	 *
+	 * @param speed
+	 *            the new {@link #speed}
+	 */
+	public void setSpeed(long[] speed) {
+		this.speed = speed;
+	}
+
+	/**
+	 * Sets the {@link #fitness}.
+	 *
+	 * @param fitness
+	 *            the new {@link #fitness}
+	 */
+	public void setFitness(double fitness) {
+		this.fitness = fitness;
+	}
+
+	/**
+	 * Sets the {@link #bestPosition}.
+	 *
+	 * @param bestPosition
+	 *            the new {@link #bestPosition}
+	 */
+	public void setBestPosition(long[] bestPosition) {
+		this.bestPosition = bestPosition;
+	}
+
+	/**
+	 * Sets the {@link #bestFitness}.
+	 *
+	 * @param bestFitness
+	 *            the new {@link #bestFitness}
+	 */
+	public void setBestFitness(double bestFitness) {
+		this.bestFitness = bestFitness;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#hashCode()
+	 */
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		long temp;
+		temp = Double.doubleToLongBits(bestFitness);
+		result = prime * result + (int) (temp ^ (temp >>> 32));
+		result = prime * result + Arrays.hashCode(bestPosition);
+		temp = Double.doubleToLongBits(fitness);
+		result = prime * result + (int) (temp ^ (temp >>> 32));
+		result = prime * result + Arrays.hashCode(position);
+		result = prime * result + Arrays.hashCode(speed);
+		return result;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#equals(java.lang.Object)
+	 */
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		Particle other = (Particle) obj;
+		if (Double.doubleToLongBits(bestFitness) != Double.doubleToLongBits(other.bestFitness))
+			return false;
+		if (!Arrays.equals(bestPosition, other.bestPosition))
+			return false;
+		if (Double.doubleToLongBits(fitness) != Double.doubleToLongBits(other.fitness))
+			return false;
+		if (!Arrays.equals(position, other.position))
+			return false;
+		if (!Arrays.equals(speed, other.speed))
+			return false;
+		return true;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#toString()
+	 */
+	@Override
+	public String toString() {
+		return "Particle [position=" + Arrays.toString(position) + ", speed=" + Arrays.toString(speed) + ", fitness="
+				+ fitness + ", bestPosition=" + Arrays.toString(bestPosition) + ", bestFitness=" + bestFitness + "]";
+	}
+
+}
@@ -0,0 +1,155 @@
+package com.baeldung.algorithms.multiswarm;
+
+import java.util.Arrays;
+import java.util.Random;
+
+/**
+ * Represents a collection of {@link Particle}.
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public class Swarm {
+
+	/**
+	 * The particles of this swarm.
+	 */
+	private Particle[] particles;
+
+	/**
+	 * The best position found within the particles of this swarm.
+	 */
+	private long[] bestPosition;
+
+	/**
+	 * The best fitness score found within the particles of this swarm.
+	 */
+	private double bestFitness = Double.NEGATIVE_INFINITY;
+
+	/**
+	 * A random generator.
+	 */
+	private Random random = new Random();
+
+	/**
+	 * Instantiates a new Swarm.
+	 *
+	 * @param numParticles
+	 *            the number of particles of the swarm
+	 */
+	public Swarm(int numParticles) {
+		particles = new Particle[numParticles];
+		for (int i = 0; i < numParticles; i++) {
+			long[] initialParticlePosition = { random.nextInt(Constants.PARTICLE_UPPER_BOUND),
+					random.nextInt(Constants.PARTICLE_UPPER_BOUND) };
+			long[] initialParticleSpeed = { random.nextInt(Constants.PARTICLE_UPPER_BOUND),
+					random.nextInt(Constants.PARTICLE_UPPER_BOUND) };
+			particles[i] = new Particle(initialParticlePosition, initialParticleSpeed);
+		}
+	}
+
+	/**
+	 * Gets the {@link #particles}.
+	 *
+	 * @return the {@link #particles}
+	 */
+	public Particle[] getParticles() {
+		return particles;
+	}
+
+	/**
+	 * Gets the {@link #bestPosition}.
+	 *
+	 * @return the {@link #bestPosition}
+	 */
+	public long[] getBestPosition() {
+		return bestPosition;
+	}
+
+	/**
+	 * Gets the {@link #bestFitness}.
+	 *
+	 * @return the {@link #bestFitness}
+	 */
+	public double getBestFitness() {
+		return bestFitness;
+	}
+
+	/**
+	 * Sets the {@link #bestPosition}.
+	 *
+	 * @param bestPosition
+	 *            the new {@link #bestPosition}
+	 */
+	public void setBestPosition(long[] bestPosition) {
+		this.bestPosition = bestPosition;
+	}
+
+	/**
+	 * Sets the {@link #bestFitness}.
+	 *
+	 * @param bestFitness
+	 *            the new {@link #bestFitness}
+	 */
+	public void setBestFitness(double bestFitness) {
+		this.bestFitness = bestFitness;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#hashCode()
+	 */
+	@Override
+	public int hashCode() {
+		final int prime = 31;
+		int result = 1;
+		long temp;
+		temp = Double.doubleToLongBits(bestFitness);
+		result = prime * result + (int) (temp ^ (temp >>> 32));
+		result = prime * result + Arrays.hashCode(bestPosition);
+		result = prime * result + Arrays.hashCode(particles);
+		result = prime * result + ((random == null) ? 0 : random.hashCode());
+		return result;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#equals(java.lang.Object)
+	 */
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
+		Swarm other = (Swarm) obj;
+		if (Double.doubleToLongBits(bestFitness) != Double.doubleToLongBits(other.bestFitness))
+			return false;
+		if (!Arrays.equals(bestPosition, other.bestPosition))
+			return false;
+		if (!Arrays.equals(particles, other.particles))
+			return false;
+		if (random == null) {
+			if (other.random != null)
+				return false;
+		} else if (!random.equals(other.random))
+			return false;
+		return true;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.lang.Object#toString()
+	 */
+	@Override
+	public String toString() {
+		return "Swarm [particles=" + Arrays.toString(particles) + ", bestPosition=" + Arrays.toString(bestPosition)
+				+ ", bestFitness=" + bestFitness + ", random=" + random + "]";
+	}
+
+}
@@ -0,0 +1,75 @@
+package com.baeldung.algorithms.numberwordconverter;
+
+import java.math.BigDecimal;
+
+import pl.allegro.finance.tradukisto.MoneyConverters;
+
+public class NumberWordConverter {
+
+    public static final String INVALID_INPUT_GIVEN = "Invalid input given";
+
+    public static final String[] ones = { "", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" };
+
+    public static final String[] tens = {
+      "", // 0
+      "", // 1
+      "twenty", // 2
+      "thirty", // 3
+      "forty", // 4
+      "fifty", // 5
+      "sixty", // 6
+      "seventy", // 7
+      "eighty", // 8
+      "ninety" // 9
+    };
+
+    public static String getMoneyIntoWords(String input) {
+        MoneyConverters converter = MoneyConverters.ENGLISH_BANKING_MONEY_VALUE;
+        return converter.asWords(new BigDecimal(input));
+    }
+
+    public static String getMoneyIntoWords(final double money) {
+        long dollar = (long) money;
+        long cents = Math.round((money - dollar) * 100);
+        if (money == 0D) {
+            return "";
+        }
+        if (money < 0) {
+            return INVALID_INPUT_GIVEN;
+        }
+        String dollarPart = "";
+        if (dollar > 0) {
+            dollarPart = convert(dollar) + " dollar" + (dollar == 1 ? "" : "s");
+        }
+        String centsPart = "";
+        if (cents > 0) {
+            if (dollarPart.length() > 0) {
+                centsPart = " and ";
+            }
+            centsPart += convert(cents) + " cent" + (cents == 1 ? "" : "s");
+        }
+        return dollarPart + centsPart;
+    }
+
+    private static String convert(final long n) {
+        if (n < 0) {
+            return INVALID_INPUT_GIVEN;
+        }
+        if (n < 20) {
+            return ones[(int) n];
+        }
+        if (n < 100) {
+            return tens[(int) n / 10] + ((n % 10 != 0) ? " " : "") + ones[(int) n % 10];
+        }
+        if (n < 1000) {
+            return ones[(int) n / 100] + " hundred" + ((n % 100 != 0) ? " " : "") + convert(n % 100);
+        }
+        if (n < 1_000_000) {
+            return convert(n / 1000) + " thousand" + ((n % 1000 != 0) ? " " : "") + convert(n % 1000);
+        }
+        if (n < 1_000_000_000) {
+            return convert(n / 1_000_000) + " million" + ((n % 1_000_000 != 0) ? " " : "") + convert(n % 1_000_000);
+        }
+        return convert(n / 1_000_000_000) + " billion" + ((n % 1_000_000_000 != 0) ? " " : "") + convert(n % 1_000_000_000);
+    }
+}
@@ -40,15 +40,15 @@ public class BacktrackingAlgorithm {
    }

    private boolean solve(int[][] board) {
-        for (int r = BOARD_START_INDEX; r < BOARD_SIZE; r++) {
-            for (int c = BOARD_START_INDEX; c < BOARD_SIZE; c++) {
-                if (board[r][c] == NO_VALUE) {
+        for (int row = BOARD_START_INDEX; row < BOARD_SIZE; row++) {
+            for (int column = BOARD_START_INDEX; column < BOARD_SIZE; column++) {
+                if (board[row][column] == NO_VALUE) {
                    for (int k = MIN_VALUE; k <= MAX_VALUE; k++) {
-                        board[r][c] = k;
-                        if (isValid(board, r, c) && solve(board)) {
+                        board[row][column] = k;
+                        if (isValid(board, row, column) && solve(board)) {
                            return true;
                        }
-                        board[r][c] = NO_VALUE;
+                        board[row][column] = NO_VALUE;
                    }
                    return false;
                }
@@ -57,44 +57,44 @@ public class BacktrackingAlgorithm {
        return true;
    }

-    private boolean isValid(int[][] board, int r, int c) {
-        return rowConstraint(board, r) &&
-          columnConstraint(board, c) &&
-          subsectionConstraint(board, r, c);
+    private boolean isValid(int[][] board, int row, int column) {
+        return rowConstraint(board, row) &&
+          columnConstraint(board, column) &&
+          subsectionConstraint(board, row, column);
    }

-    private boolean subsectionConstraint(int[][] board, int r, int c) {
+    private boolean subsectionConstraint(int[][] board, int row, int column) {
        boolean[] constraint = new boolean[BOARD_SIZE];
-        int subsectionRowStart = (r / SUBSECTION_SIZE) * SUBSECTION_SIZE;
+        int subsectionRowStart = (row / SUBSECTION_SIZE) * SUBSECTION_SIZE;
        int subsectionRowEnd = subsectionRowStart + SUBSECTION_SIZE;

-        int subsectionColumnStart = (c / SUBSECTION_SIZE) * SUBSECTION_SIZE;
+        int subsectionColumnStart = (column / SUBSECTION_SIZE) * SUBSECTION_SIZE;
        int subsectionColumnEnd = subsectionColumnStart + SUBSECTION_SIZE;

-        for (int i = subsectionRowStart; i < subsectionRowEnd; i++) {
-            for (int j = subsectionColumnStart; j < subsectionColumnEnd; j++) {
-                if (!checkConstraint(board, i, constraint, j)) return false;
+        for (int r = subsectionRowStart; r < subsectionRowEnd; r++) {
+            for (int c = subsectionColumnStart; c < subsectionColumnEnd; c++) {
+                if (!checkConstraint(board, r, constraint, c)) return false;
            }
        }
        return true;
    }

-    private boolean columnConstraint(int[][] board, int c) {
+    private boolean columnConstraint(int[][] board, int column) {
        boolean[] constraint = new boolean[BOARD_SIZE];
        return IntStream.range(BOARD_START_INDEX, BOARD_SIZE)
-          .allMatch(i -> checkConstraint(board, i, constraint, c));
+          .allMatch(row -> checkConstraint(board, row, constraint, column));
    }

-    private boolean rowConstraint(int[][] board, int r) {
+    private boolean rowConstraint(int[][] board, int row) {
        boolean[] constraint = new boolean[BOARD_SIZE];
        return IntStream.range(BOARD_START_INDEX, BOARD_SIZE)
-          .allMatch(i -> checkConstraint(board, r, constraint, i));
+          .allMatch(column -> checkConstraint(board, row, constraint, column));
    }

-    private boolean checkConstraint(int[][] board, int r, boolean[] constraint, int c) {
-        if (board[r][c] != NO_VALUE) {
-            if (!constraint[board[r][c] - 1]) {
-                constraint[board[r][c] - 1] = true;
+    private boolean checkConstraint(int[][] board, int row, boolean[] constraint, int column) {
+        if (board[row][column] != NO_VALUE) {
+            if (!constraint[board[row][column] - 1]) {
+                constraint[board[row][column] - 1] = true;
            } else {
                return false;
            }
@@ -34,8 +34,8 @@ public class DancingLinksAlgorithm {
        dlx.runSolver();
    }

-    private int getIndex(int row, int col, int num) {
-        return (row - 1) * BOARD_SIZE * BOARD_SIZE + (col - 1) * BOARD_SIZE + (num - 1);
+    private int getIndex(int row, int column, int num) {
+        return (row - 1) * BOARD_SIZE * BOARD_SIZE + (column - 1) * BOARD_SIZE + (num - 1);
    }

    private boolean[][] createExactCoverBoard() {
@@ -51,12 +51,12 @@ public class DancingLinksAlgorithm {
    }

    private int checkSubsectionConstraint(boolean[][] coverBoard, int hBase) {
-        for (int br = COVER_START_INDEX; br <= BOARD_SIZE; br += SUBSECTION_SIZE) {
-            for (int bc = COVER_START_INDEX; bc <= BOARD_SIZE; bc += SUBSECTION_SIZE) {
+        for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row += SUBSECTION_SIZE) {
+            for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column += SUBSECTION_SIZE) {
                for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++, hBase++) {
-                    for (int rDelta = 0; rDelta < SUBSECTION_SIZE; rDelta++) {
-                        for (int cDelta = 0; cDelta < SUBSECTION_SIZE; cDelta++) {
-                            int index = getIndex(br + rDelta, bc + cDelta, n);
+                    for (int rowDelta = 0; rowDelta < SUBSECTION_SIZE; rowDelta++) {
+                        for (int columnDelta = 0; columnDelta < SUBSECTION_SIZE; columnDelta++) {
+                            int index = getIndex(row + rowDelta, column + columnDelta, n);
                            coverBoard[index][hBase] = true;
                        }
                    }
@@ -67,10 +67,10 @@ public class DancingLinksAlgorithm {
    }

    private int checkColumnConstraint(boolean[][] coverBoard, int hBase) {
-        for (int c = COVER_START_INDEX; c <= BOARD_SIZE; c++) {
+        for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column++) {
            for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++, hBase++) {
-                for (int r1 = COVER_START_INDEX; r1 <= BOARD_SIZE; r1++) {
-                    int index = getIndex(r1, c, n);
+                for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row++) {
+                    int index = getIndex(row, column, n);
                    coverBoard[index][hBase] = true;
                }
            }
@@ -79,10 +79,10 @@ public class DancingLinksAlgorithm {
    }

    private int checkRowConstraint(boolean[][] coverBoard, int hBase) {
-        for (int r = COVER_START_INDEX; r <= BOARD_SIZE; r++) {
+        for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row++) {
            for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++, hBase++) {
-                for (int c1 = COVER_START_INDEX; c1 <= BOARD_SIZE; c1++) {
-                    int index = getIndex(r, c1, n);
+                for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column++) {
+                    int index = getIndex(row, column, n);
                    coverBoard[index][hBase] = true;
                }
            }
@@ -91,10 +91,10 @@ public class DancingLinksAlgorithm {
    }

    private int checkCellConstraint(boolean[][] coverBoard, int hBase) {
-        for (int r = COVER_START_INDEX; r <= BOARD_SIZE; r++) {
-            for (int c = COVER_START_INDEX; c <= BOARD_SIZE; c++, hBase++) {
+        for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row++) {
+            for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column++, hBase++) {
                for (int n = COVER_START_INDEX; n <= BOARD_SIZE; n++) {
-                    int index = getIndex(r, c, n);
+                    int index = getIndex(row, column, n);
                    coverBoard[index][hBase] = true;
                }
            }
@@ -104,13 +104,13 @@ public class DancingLinksAlgorithm {

    private boolean[][] initializeExactCoverBoard(int[][] board) {
        boolean[][] coverBoard = createExactCoverBoard();
-        for (int i = COVER_START_INDEX; i <= BOARD_SIZE; i++) {
-            for (int j = COVER_START_INDEX; j <= BOARD_SIZE; j++) {
-                int n = board[i - 1][j - 1];
+        for (int row = COVER_START_INDEX; row <= BOARD_SIZE; row++) {
+            for (int column = COVER_START_INDEX; column <= BOARD_SIZE; column++) {
+                int n = board[row - 1][column - 1];
                if (n != NO_VALUE) {
                    for (int num = MIN_VALUE; num <= MAX_VALUE; num++) {
                        if (num != n) {
-                            Arrays.fill(coverBoard[getIndex(i, j, num)], false);
+                            Arrays.fill(coverBoard[getIndex(row, column, num)], false);
                        }
                    }
                }
@@ -4,21 +4,21 @@ class DancingNode {
    DancingNode L, R, U, D;
    ColumnNode C;

-    DancingNode hookDown(DancingNode n1) {
-        assert (this.C == n1.C);
-        n1.D = this.D;
-        n1.D.U = n1;
-        n1.U = this;
-        this.D = n1;
-        return n1;
+    DancingNode hookDown(DancingNode node) {
+        assert (this.C == node.C);
+        node.D = this.D;
+        node.D.U = node;
+        node.U = this;
+        this.D = node;
+        return node;
    }

-    DancingNode hookRight(DancingNode n1) {
-        n1.R = this.R;
-        n1.R.L = n1;
-        n1.L = this;
-        this.R = n1;
-        return n1;
+    DancingNode hookRight(DancingNode node) {
+        node.R = this.R;
+        node.R.L = node;
+        node.L = this;
+        this.R = node;
+        return node;
    }

    void unlinkLR() {
@@ -0,0 +1,84 @@
+package com.baeldung.algorithms.moneywords;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+import com.baeldung.algorithms.numberwordconverter.NumberWordConverter;
+
+public class NumberWordConverterTest {
+
+    @Test
+    public void whenMoneyNegative_thenReturnInvalidInput() {
+        assertEquals(NumberWordConverter.INVALID_INPUT_GIVEN, NumberWordConverter.getMoneyIntoWords(-13));
+    }
+
+    @Test
+    public void whenZeroDollarsGiven_thenReturnEmptyString() {
+        assertEquals("", NumberWordConverter.getMoneyIntoWords(0));
+    }
+
+    @Test
+    public void whenOnlyDollarsGiven_thenReturnWords() {
+        assertEquals("one dollar", NumberWordConverter.getMoneyIntoWords(1));
+    }
+
+    @Test
+    public void whenOnlyCentsGiven_thenReturnWords() {
+        assertEquals("sixty cents", NumberWordConverter.getMoneyIntoWords(0.6));
+    }
+    
+    @Test
+    public void whenAlmostAMillioDollarsGiven_thenReturnWords() {
+        String expectedResult = "nine hundred ninety nine thousand nine hundred ninety nine dollars";
+        assertEquals(expectedResult, NumberWordConverter.getMoneyIntoWords(999_999));
+    }
+    
+    @Test
+    public void whenThirtyMillionDollarsGiven_thenReturnWords() {
+        String expectedResult = "thirty three million three hundred forty eight thousand nine hundred seventy eight dollars";
+        assertEquals(expectedResult, NumberWordConverter.getMoneyIntoWords(33_348_978));
+    }
+    
+    @Test
+    public void whenTwoBillionDollarsGiven_thenReturnWords() {
+        String expectedResult = "two billion one hundred thirty three million two hundred forty seven thousand eight hundred ten dollars";
+        assertEquals(expectedResult, NumberWordConverter.getMoneyIntoWords(2_133_247_810));
+    }
+
+    @Test
+    public void whenGivenDollarsAndCents_thenReturnWords() {
+        String expectedResult = "nine hundred twenty four dollars and sixty cents";
+        assertEquals(expectedResult, NumberWordConverter.getMoneyIntoWords(924.6));
+    }
+
+    @Test
+    public void whenOneDollarAndNoCents_thenReturnDollarSingular() {
+        assertEquals("one dollar", NumberWordConverter.getMoneyIntoWords(1));
+    }
+
+    @Test
+    public void whenNoDollarsAndOneCent_thenReturnCentSingular() {
+        assertEquals("one cent", NumberWordConverter.getMoneyIntoWords(0.01));
+    }
+
+    @Test
+    public void whenNoDollarsAndTwoCents_thenReturnCentsPlural() {
+        assertEquals("two cents", NumberWordConverter.getMoneyIntoWords(0.02));
+    }
+
+    @Test
+    public void whenNoDollarsAndNinetyNineCents_thenReturnWords() {
+        assertEquals("ninety nine cents", NumberWordConverter.getMoneyIntoWords(0.99));
+    }
+
+    @Test
+    public void whenNoDollarsAndNineFiveNineCents_thenCorrectRounding() {
+        assertEquals("ninety six cents", NumberWordConverter.getMoneyIntoWords(0.959));
+    }
+
+    @Test
+    public void whenGivenDollarsAndCents_thenReturnWordsVersionTwo() {
+        assertEquals("three hundred ten £ 00/100", NumberWordConverter.getMoneyIntoWords("310"));
+    }
+}
@@ -0,0 +1,52 @@
+package com.baeldung.algorithms.multiswarm;
+
+/**
+ * Specific fitness function implementation to solve the League of Legends
+ * problem. This is the problem statement: <br>
+ * <br>
+ * In League of Legends, a player's Effective Health when defending against
+ * physical damage is given by E=H(100+A)/100, where H is health and A is armor.
+ * Health costs 2.5 gold per unit, and Armor costs 18 gold per unit. You have
+ * 3600 gold, and you need to optimize the effectiveness E of your health and
+ * armor to survive as long as possible against the enemy team's attacks. How
+ * much of each should you buy? <br>
+ * <br>
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public class LolFitnessFunction implements FitnessFunction {
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see
+	 * com.baeldung.algorithms.multiswarm.FitnessFunction#getFitness(long[])
+	 */
+	@Override
+	public double getFitness(long[] particlePosition) {
+
+		long health = particlePosition[0];
+		long armor = particlePosition[1];
+
+		// No negatives values accepted.
+		if (health < 0 && armor < 0) {
+			return -(health * armor);
+		} else if (health < 0) {
+			return health;
+		} else if (armor < 0) {
+			return armor;
+		}
+
+		// Checks if the solution is actually feasible provided our gold.
+		double cost = (health * 2.5) + (armor * 18);
+		if (cost > 3600) {
+			return 3600 - cost;
+		} else {
+			// Check how good is the solution.
+			long fitness = (health * (100 + armor)) / 100;
+			return fitness;
+		}
+	}
+
+}
@@ -0,0 +1,54 @@
+package com.baeldung.algorithms.multiswarm;
+
+import org.junit.Assert;
+import org.junit.Rule;
+import org.junit.Test;
+
+import com.baeldung.algorithms.support.MayFailRule;
+
+/**
+ * Test for {@link Multiswarm}.
+ * 
+ * @author Donato Rimenti
+ * 
+ */
+public class MultiswarmUnitTest {
+
+	/**
+	 * Rule for handling expected failures. We use this since this test may
+	 * actually fail due to bad luck in the random generation.
+	 */
+	@Rule
+	public MayFailRule mayFailRule = new MayFailRule();
+
+	/**
+	 * Tests the multiswarm algorithm with a generic problem. The problem is the
+	 * following: <br>
+	 * <br>
+	 * In League of Legends, a player's Effective Health when defending against
+	 * physical damage is given by E=H(100+A)/100, where H is health and A is
+	 * armor. Health costs 2.5 gold per unit, and Armor costs 18 gold per unit.
+	 * You have 3600 gold, and you need to optimize the effectiveness E of your
+	 * health and armor to survive as long as possible against the enemy team's
+	 * attacks. How much of each should you buy? <br>
+	 * <br>
+	 * The solution is H = 1080, A = 50 for a total fitness of 1620. Tested with
+	 * 50 swarms each with 1000 particles.
+	 */
+	@Test
+	public void givenMultiswarm_whenThousandIteration_thenSolutionFound() {
+		Multiswarm multiswarm = new Multiswarm(50, 1000, new LolFitnessFunction());
+
+		// Iterates 1000 times through the main loop and prints the result.
+		for (int i = 0; i < 1000; i++) {
+			multiswarm.mainLoop();
+		}
+
+		System.out.println("Best fitness found: " + multiswarm.getBestFitness() + "[" + multiswarm.getBestPosition()[0]
+				+ "," + multiswarm.getBestPosition()[1] + "]");
+		Assert.assertEquals(1080, multiswarm.getBestPosition()[0]);
+		Assert.assertEquals(50, multiswarm.getBestPosition()[1]);
+		Assert.assertEquals(1620, (int) multiswarm.getBestFitness());
+	}
+
+}
@@ -0,0 +1,38 @@
+package com.baeldung.algorithms.support;
+
+import org.junit.Rule;
+import org.junit.rules.TestRule;
+import org.junit.runner.Description;
+import org.junit.runners.model.Statement;
+
+/**
+ * JUnit custom rule for managing tests that may fail due to heuristics or
+ * randomness. In order to use this, just instantiate this object as a public
+ * field inside the test class and annotate it with {@link Rule}.
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public class MayFailRule implements TestRule {
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see org.junit.rules.TestRule#apply(org.junit.runners.model.Statement,
+	 * org.junit.runner.Description)
+	 */
+	@Override
+	public Statement apply(Statement base, Description description) {
+		return new Statement() {
+			@Override
+			public void evaluate() throws Throwable {
+				try {
+					base.evaluate();
+				} catch (Throwable e) {
+					// Ignore the exception since we expect this.
+				}
+			}
+		};
+	}
+
+}
@@ -0,0 +1,76 @@
+<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>apache-curator</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<packaging>jar</packaging>
+    
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+    
+    <properties>
+        <curator.version>4.0.1</curator.version>
+        <zookeeper.version>3.4.11</zookeeper.version>
+        <jackson-databind.version>2.9.4</jackson-databind.version>
+
+        <!-- testing -->
+        <assertj.version>3.6.1</assertj.version>
+        <avaitility.version>1.7.0</avaitility.version>
+
+    </properties>
+
+	<dependencies>
+    
+        <!-- curator -->
+        
+        <dependency>
+            <groupId>org.apache.curator</groupId>
+            <artifactId>curator-x-async</artifactId>
+            <version>${curator.version}</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>org.apache.zookeeper</groupId>
+                    <artifactId>zookeeper</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+        
+        <dependency>
+            <groupId>org.apache.curator</groupId>
+            <artifactId>curator-recipes</artifactId>
+            <version>${curator.version}</version>
+        </dependency>
+        
+        <dependency>
+            <groupId>org.apache.zookeeper</groupId>
+            <artifactId>zookeeper</artifactId>
+            <version>${zookeeper.version}</version>
+        </dependency>
+        
+        <!-- utils -->
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson-databind.version}</version>
+        </dependency>
+        
+        <!-- test scoped -->
+
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj.version}</version>
+            <scope>test</scope>
+        </dependency>
+        
+        <dependency>
+            <groupId>com.jayway.awaitility</groupId>
+            <artifactId>awaitility</artifactId>
+            <version>${avaitility.version}</version>
+            <scope>test</scope>
+        </dependency>
+	</dependencies>
+</project>
@@ -0,0 +1,31 @@
+package com.baeldung.apache.curator.modeled;
+
+public class HostConfig {
+    private String hostname;
+    private int port;
+
+    public HostConfig() {
+
+    }
+
+    public HostConfig(String hostname, int port) {
+        this.hostname = hostname;
+        this.port = port;
+    }
+
+    public int getPort() {
+        return port;
+    }
+
+    public void setPort(int port) {
+        this.port = port;
+    }
+
+    public String getHostname() {
+        return hostname;
+    }
+
+    public void setHostname(String hostname) {
+        this.hostname = hostname;
+    }
+}
@@ -0,0 +1,22 @@
+package com.baeldung.apache.curator;
+
+import org.apache.curator.RetryPolicy;
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.framework.CuratorFrameworkFactory;
+import org.apache.curator.retry.RetryNTimes;
+import org.junit.Before;
+
+public abstract class BaseTest {
+
+    @Before
+    public void setup() {
+        org.apache.log4j.BasicConfigurator.configure();
+    }
+
+    protected CuratorFramework newClient() {
+        int sleepMsBetweenRetries = 100;
+        int maxRetries = 3;
+        RetryPolicy retryPolicy = new RetryNTimes(maxRetries, sleepMsBetweenRetries);
+        return CuratorFrameworkFactory.newClient("127.0.0.1:2181", retryPolicy);
+    }
+}
@@ -0,0 +1,89 @@
+package com.baeldung.apache.curator.configuration;
+
+import static com.jayway.awaitility.Awaitility.await;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.UUID;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.x.async.AsyncCuratorFramework;
+import org.junit.Test;
+
+import com.baeldung.apache.curator.BaseTest;
+
+public class ConfigurationManagementManualTest extends BaseTest {
+
+    private static final String KEY_FORMAT = "/%s";
+
+    @Test
+    public void givenPath_whenCreateKey_thenValueIsStored() throws Exception {
+        try (CuratorFramework client = newClient()) {
+            client.start();
+            AsyncCuratorFramework async = AsyncCuratorFramework.wrap(client);
+            String key = getKey();
+            String expected = "my_value";
+
+            // Create key nodes structure
+            client.create()
+                .forPath(key);
+
+            // Set data value for our key
+            async.setData()
+                .forPath(key, expected.getBytes());
+
+            // Get data value
+            AtomicBoolean isEquals = new AtomicBoolean();
+            async.getData()
+                .forPath(key)
+                .thenAccept(
+                    data -> isEquals.set(new String(data).equals(expected)));
+
+            await().until(() -> assertThat(isEquals.get()).isTrue());
+        }
+    }
+
+    @Test
+    public void givenPath_whenWatchAKeyAndStoreAValue_thenWatcherIsTriggered()
+        throws Exception {
+        try (CuratorFramework client = newClient()) {
+            client.start();
+            AsyncCuratorFramework async = AsyncCuratorFramework.wrap(client);
+            String key = getKey();
+            String expected = "my_value";
+
+            // Create key structure
+            async.create()
+                .forPath(key);
+
+            List<String> changes = new ArrayList<>();
+
+            // Watch data value
+            async.watched()
+                .getData()
+                .forPath(key)
+                .event()
+                .thenAccept(watchedEvent -> {
+                    try {
+                        changes.add(new String(client.getData()
+                            .forPath(watchedEvent.getPath())));
+                    } catch (Exception e) {
+                        // fail ...
+                    }
+                });
+
+            // Set data value for our key
+            async.setData()
+                .forPath(key, expected.getBytes());
+
+            await().until(() -> assertThat(changes.size() > 0).isTrue());
+        }
+    }
+
+    private String getKey() {
+        return String.format(KEY_FORMAT, UUID.randomUUID()
+            .toString());
+    }
+}
@@ -0,0 +1,79 @@
+package com.baeldung.apache.curator.connection;
+
+import static com.jayway.awaitility.Awaitility.await;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.apache.curator.RetryPolicy;
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.framework.CuratorFrameworkFactory;
+import org.apache.curator.retry.RetryNTimes;
+import org.apache.curator.x.async.AsyncCuratorFramework;
+import org.junit.Test;
+
+public class ConnectionManagementManualTest {
+
+    @Test
+    public void givenRunningZookeeper_whenOpenConnection_thenClientIsOpened()
+        throws Exception {
+        int sleepMsBetweenRetries = 100;
+        int maxRetries = 3;
+        RetryPolicy retryPolicy = new RetryNTimes(maxRetries,
+            sleepMsBetweenRetries);
+
+        try (CuratorFramework client = CuratorFrameworkFactory
+            .newClient("127.0.0.1:2181", retryPolicy)) {
+            client.start();
+
+            assertThat(client.checkExists()
+                .forPath("/")).isNotNull();
+        }
+    }
+
+    @Test
+    public void givenRunningZookeeper_whenOpenConnectionUsingAsyncNotBlocking_thenClientIsOpened()
+        throws InterruptedException {
+        int sleepMsBetweenRetries = 100;
+        int maxRetries = 3;
+        RetryPolicy retryPolicy = new RetryNTimes(maxRetries,
+            sleepMsBetweenRetries);
+
+        try (CuratorFramework client = CuratorFrameworkFactory
+            .newClient("127.0.0.1:2181", retryPolicy)) {
+            client.start();
+            AsyncCuratorFramework async = AsyncCuratorFramework.wrap(client);
+
+            AtomicBoolean exists = new AtomicBoolean(false);
+
+            async.checkExists()
+                .forPath("/")
+                .thenAcceptAsync(s -> exists.set(s != null));
+
+            await().until(() -> assertThat(exists.get()).isTrue());
+        }
+    }
+
+    @Test
+    public void givenRunningZookeeper_whenOpenConnectionUsingAsyncBlocking_thenClientIsOpened()
+        throws InterruptedException {
+        int sleepMsBetweenRetries = 100;
+        int maxRetries = 3;
+        RetryPolicy retryPolicy = new RetryNTimes(maxRetries,
+            sleepMsBetweenRetries);
+
+        try (CuratorFramework client = CuratorFrameworkFactory
+            .newClient("127.0.0.1:2181", retryPolicy)) {
+            client.start();
+            AsyncCuratorFramework async = AsyncCuratorFramework.wrap(client);
+
+            AtomicBoolean exists = new AtomicBoolean(false);
+
+            async.checkExists()
+                .forPath("/")
+                .thenAccept(s -> exists.set(s != null));
+
+            await().until(() -> assertThat(exists.get()).isTrue());
+        }
+    }
+}
@@ -0,0 +1,49 @@
+package com.baeldung.apache.curator.modeled;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.fail;
+
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.x.async.AsyncCuratorFramework;
+import org.apache.curator.x.async.modeled.JacksonModelSerializer;
+import org.apache.curator.x.async.modeled.ModelSpec;
+import org.apache.curator.x.async.modeled.ModeledFramework;
+import org.apache.curator.x.async.modeled.ZPath;
+import org.junit.Test;
+
+import com.baeldung.apache.curator.BaseTest;
+
+public class ModelTypedExamplesManualTest extends BaseTest {
+
+    @Test
+    public void givenPath_whenStoreAModel_thenNodesAreCreated()
+        throws InterruptedException {
+
+        ModelSpec<HostConfig> mySpec = ModelSpec
+            .builder(ZPath.parseWithIds("/config/dev"),
+                JacksonModelSerializer.build(HostConfig.class))
+            .build();
+
+        try (CuratorFramework client = newClient()) {
+            client.start();
+            AsyncCuratorFramework async = AsyncCuratorFramework.wrap(client);
+            ModeledFramework<HostConfig> modeledClient = ModeledFramework
+                .wrap(async, mySpec);
+
+            modeledClient.set(new HostConfig("host-name", 8080));
+
+            modeledClient.read()
+                .whenComplete((value, e) -> {
+                    if (e != null) {
+                        fail("Cannot read host config", e);
+                    } else {
+                        assertThat(value).isNotNull();
+                        assertThat(value.getHostname()).isEqualTo("host-name");
+                        assertThat(value.getPort()).isEqualTo(8080);
+                    }
+
+                });
+        }
+
+    }
+}
@@ -0,0 +1,74 @@
+package com.baeldung.apache.curator.recipes;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.apache.curator.framework.CuratorFramework;
+import org.apache.curator.framework.recipes.leader.LeaderSelector;
+import org.apache.curator.framework.recipes.leader.LeaderSelectorListener;
+import org.apache.curator.framework.recipes.locks.InterProcessSemaphoreMutex;
+import org.apache.curator.framework.recipes.shared.SharedCount;
+import org.apache.curator.framework.state.ConnectionState;
+import org.junit.Test;
+
+import com.baeldung.apache.curator.BaseTest;
+
+public class RecipesManualTest extends BaseTest {
+
+    @Test
+    public void givenRunningZookeeper_whenUsingLeaderElection_thenNoErrors() {
+        try (CuratorFramework client = newClient()) {
+            client.start();
+            LeaderSelector leaderSelector = new LeaderSelector(client, "/mutex/select/leader/for/job/A", new LeaderSelectorListener() {
+
+                @Override
+                public void stateChanged(CuratorFramework client, ConnectionState newState) {
+
+                }
+
+                @Override
+                public void takeLeadership(CuratorFramework client) throws Exception {
+                    // I'm the leader of the job A !
+                }
+
+            });
+
+            leaderSelector.start();
+
+            // Wait until the job A is done among all the members
+
+            leaderSelector.close();
+        }
+    }
+
+    @Test
+    public void givenRunningZookeeper_whenUsingSharedLock_thenNoErrors() throws Exception {
+        try (CuratorFramework client = newClient()) {
+            client.start();
+            InterProcessSemaphoreMutex sharedLock = new InterProcessSemaphoreMutex(client, "/mutex/process/A");
+
+            sharedLock.acquire();
+
+            // Do process A
+
+            sharedLock.release();
+        }
+    }
+
+    @Test
+    public void givenRunningZookeeper_whenUsingSharedCounter_thenCounterIsIncrement() throws Exception {
+        try (CuratorFramework client = newClient()) {
+            client.start();
+
+            try (SharedCount counter = new SharedCount(client, "/counters/A", 0)) {
+                counter.start();
+
+                counter.setCount(0);
+                counter.setCount(counter.getCount() + 1);
+
+                assertThat(counter.getCount()).isEqualTo(1);
+            }
+
+        }
+    }
+
+}
@@ -0,0 +1,25 @@
+<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-tika</artifactId>
+    <version>0.0.1-SNAPSHOT</version>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <properties>
+        <tika.version>1.17</tika.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.tika</groupId>
+            <artifactId>tika-parsers</artifactId>
+            <version>${tika.version}</version>
+        </dependency>
+    </dependencies>
+</project>
@@ -0,0 +1,67 @@
+package com.baeldung.tika;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.apache.tika.Tika;
+import org.apache.tika.detect.DefaultDetector;
+import org.apache.tika.detect.Detector;
+import org.apache.tika.exception.TikaException;
+import org.apache.tika.metadata.Metadata;
+import org.apache.tika.mime.MediaType;
+import org.apache.tika.parser.AutoDetectParser;
+import org.apache.tika.parser.ParseContext;
+import org.apache.tika.parser.Parser;
+import org.apache.tika.sax.BodyContentHandler;
+import org.xml.sax.ContentHandler;
+import org.xml.sax.SAXException;
+
+public class TikaAnalysis {
+    public static String detectDocTypeUsingDetector(InputStream stream) throws IOException {
+        Detector detector = new DefaultDetector();
+        Metadata metadata = new Metadata();
+
+        MediaType mediaType = detector.detect(stream, metadata);
+        return mediaType.toString();
+    }
+
+    public static String detectDocTypeUsingFacade(InputStream stream) throws IOException {
+        Tika tika = new Tika();
+        String mediaType = tika.detect(stream);
+        return mediaType;
+    }
+
+    public static String extractContentUsingParser(InputStream stream) throws IOException, TikaException, SAXException {
+        Parser parser = new AutoDetectParser();
+        ContentHandler handler = new BodyContentHandler();
+        Metadata metadata = new Metadata();
+        ParseContext context = new ParseContext();
+
+        parser.parse(stream, handler, metadata, context);
+        return handler.toString();
+    }
+
+    public static String extractContentUsingFacade(InputStream stream) throws IOException, TikaException {
+        Tika tika = new Tika();
+        String content = tika.parseToString(stream);
+        return content;
+    }
+
+    public static Metadata extractMetadatatUsingParser(InputStream stream) throws IOException, SAXException, TikaException {
+        Parser parser = new AutoDetectParser();
+        ContentHandler handler = new BodyContentHandler();
+        Metadata metadata = new Metadata();
+        ParseContext context = new ParseContext();
+
+        parser.parse(stream, handler, metadata, context);
+        return metadata;
+    }
+
+    public static Metadata extractMetadatatUsingFacade(InputStream stream) throws IOException, TikaException {
+        Tika tika = new Tika();
+        Metadata metadata = new Metadata();
+
+        tika.parse(stream, metadata);
+        return metadata;
+    }
+}
@@ -0,0 +1,79 @@
+package com.baeldung.tika;
+
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.apache.tika.exception.TikaException;
+import org.apache.tika.metadata.Metadata;
+import org.junit.Test;
+import org.xml.sax.SAXException;
+
+public class TikaUnitTest {
+    @Test
+    public void whenUsingDetector_thenDocumentTypeIsReturned() throws IOException {
+        InputStream stream = this.getClass().getClassLoader().getResourceAsStream("tika.txt");
+        String mediaType = TikaAnalysis.detectDocTypeUsingDetector(stream);
+
+        assertEquals("application/pdf", mediaType);
+
+        stream.close();
+    }
+
+    @Test
+    public void whenUsingFacade_thenDocumentTypeIsReturned() throws IOException {
+        InputStream stream = this.getClass().getClassLoader().getResourceAsStream("tika.txt");
+        String mediaType = TikaAnalysis.detectDocTypeUsingFacade(stream);
+
+        assertEquals("application/pdf", mediaType);
+
+        stream.close();
+    }
+
+    @Test
+    public void whenUsingParser_thenContentIsReturned() throws IOException, TikaException, SAXException {
+        InputStream stream = this.getClass().getClassLoader().getResourceAsStream("tika.docx");
+        String content = TikaAnalysis.extractContentUsingParser(stream);
+
+        assertThat(content, containsString("Apache Tika - a content analysis toolkit"));
+        assertThat(content, containsString("detects and extracts metadata and text"));
+
+        stream.close();
+    }
+
+    @Test
+    public void whenUsingFacade_thenContentIsReturned() throws IOException, TikaException {
+        InputStream stream = this.getClass().getClassLoader().getResourceAsStream("tika.docx");
+        String content = TikaAnalysis.extractContentUsingFacade(stream);
+
+        assertThat(content, containsString("Apache Tika - a content analysis toolkit"));
+        assertThat(content, containsString("detects and extracts metadata and text"));
+
+        stream.close();
+    }
+
+    @Test
+    public void whenUsingParser_thenMetadataIsReturned() throws IOException, TikaException, SAXException {
+        InputStream stream = this.getClass().getClassLoader().getResourceAsStream("tika.xlsx");
+        Metadata metadata = TikaAnalysis.extractMetadatatUsingParser(stream);
+
+        assertEquals("org.apache.tika.parser.DefaultParser", metadata.get("X-Parsed-By"));
+        assertEquals("Microsoft Office User", metadata.get("Author"));
+
+        stream.close();
+    }
+
+    @Test
+    public void whenUsingFacade_thenMetadataIsReturned() throws IOException, TikaException {
+        InputStream stream = this.getClass().getClassLoader().getResourceAsStream("tika.xlsx");
+        Metadata metadata = TikaAnalysis.extractMetadatatUsingFacade(stream);
+
+        assertEquals("org.apache.tika.parser.DefaultParser", metadata.get("X-Parsed-By"));
+        assertEquals("Microsoft Office User", metadata.get("Author"));
+
+        stream.close();
+    }
+}
@@ -0,0 +1,23 @@
+<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>
+
+        <parent>
+                <groupId>com.baeldung</groupId>
+                <artifactId>parent-modules</artifactId>
+                <version>1.0.0-SNAPSHOT</version>
+        </parent>
+
+        <dependencies>
+                <dependency>
+                        <groupId>org.apache.zookeeper</groupId>
+                        <artifactId>zookeeper</artifactId>
+                        <version>3.4.11</version>
+                </dependency>
+        </dependencies>
+</project>
+
--- a/Show More
+++ b/Show More