This commit is contained in:
orrym 2018-03-01 16:11:56 +02:00
commit 48cd7fe8fa
356 changed files with 11875 additions and 602 deletions

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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 particles 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() {
}
}

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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);
}

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@ -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 + "]";
}
}

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@ -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 + "]";
}
}

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@ -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 + "]";
}
}

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@ -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;
}

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@ -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);
}
}
}

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@ -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() {

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@ -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;
}
}
}

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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());
}
}

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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.
}
}
};
}
}

30
apache-zookeeper/pom.xml Normal file
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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.baeldung</groupId>
<artifactId>apache-zookeeper</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.apache.zookeeper</groupId>
<artifactId>zookeeper</artifactId>
<version>3.3.2</version>
<exclusions>
<exclusion>
<groupId>com.sun.jmx</groupId>
<artifactId>jmxri</artifactId>
</exclusion>
<exclusion>
<groupId>com.sun.jdmk</groupId>
<artifactId>jmxtools</artifactId>
</exclusion>
<exclusion>
<groupId>javax.jms</groupId>
<artifactId>jms</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
</project>

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package com.baeldung.zookeeper.connection;
import java.io.IOException;
import java.util.concurrent.CountDownLatch;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.Watcher.Event.KeeperState;
import org.apache.zookeeper.ZooKeeper;
public class ZKConnection {
private ZooKeeper zoo;
final CountDownLatch connectionLatch = new CountDownLatch(1);
public ZKConnection() {
}
public ZooKeeper connect(String host) throws IOException, InterruptedException {
zoo = new ZooKeeper(host, 2000, new Watcher() {
public void process(WatchedEvent we) {
if (we.getState() == KeeperState.SyncConnected) {
connectionLatch.countDown();
}
}
});
connectionLatch.await();
return zoo;
}
public void close() throws InterruptedException {
zoo.close();
}
}

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package com.baeldung.zookeeper.manager;
import org.apache.zookeeper.KeeperException;
public interface ZKManager {
/**
* Create a Znode and save some data
*
* @param path
* @param data
* @throws KeeperException
* @throws InterruptedException
*/
public void create(String path, byte[] data) throws KeeperException, InterruptedException;
/**
* Get ZNode Data
*
* @param path
* @param boolean watchFlag
* @throws KeeperException
* @throws InterruptedException
*/
public Object getZNodeData(String path, boolean watchFlag);
/**
* Update the ZNode Data
*
* @param path
* @param data
* @throws KeeperException
* @throws InterruptedException
*/
public void update(String path, byte[] data) throws KeeperException, InterruptedException, KeeperException;
}

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package com.baeldung.zookeeper.manager;
import org.apache.zookeeper.CreateMode;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.ZooKeeper;
import com.baeldung.zookeeper.connection.ZKConnection;
public class ZKManagerImpl implements ZKManager {
private static ZooKeeper zkeeper;
private static ZKConnection zkConnection;
public ZKManagerImpl() {
initialize();
}
/** * Initialize connection */
private void initialize() {
try {
zkConnection = new ZKConnection();
zkeeper = zkConnection.connect("localhost");
} catch (Exception e) {
System.out.println(e.getMessage());
}
}
public void closeConnection() {
try {
zkConnection.close();
} catch (InterruptedException e) {
System.out.println(e.getMessage());
}
}
public void create(String path, byte[] data) throws KeeperException, InterruptedException {
zkeeper.create(path, data, ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
}
public Object getZNodeData(String path, boolean watchFlag) {
try {
byte[] b = null;
b = zkeeper.getData(path, null, null);
String data = new String(b, "UTF-8");
System.out.println(data);
return data;
} catch (Exception e) {
System.out.println(e.getMessage());
}
return null;
}
public void update(String path, byte[] data) throws KeeperException, InterruptedException {
int version = zkeeper.exists(path, true)
.getVersion();
zkeeper.setData(path, data, version);
}
}

114
checker-plugin/pom.xml Normal file
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<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.baeldung</groupId>
<artifactId>checker-plugin</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>checker-plugin</name>
<url>http://maven.apache.org</url>
<!-- https://checkerframework.org/manual/#maven -->
<properties>
<!-- These properties will be set by the Maven Dependency plugin -->
<annotatedJdk>${org.checkerframework:jdk8:jar}</annotatedJdk>
<!-- Uncomment to use the Type Annotations compiler. -->
<!--
<typeAnnotationsJavac>${org.checkerframework:compiler:jar}</typeAnnotationsJavac>
-->
</properties>
<dependencies>
<!-- Annotations from the Checker Framework: nullness, interning, locking, ... -->
<dependency>
<groupId>org.checkerframework</groupId>
<artifactId>checker-qual</artifactId>
<version>2.3.1</version>
</dependency>
<dependency>
<groupId>org.checkerframework</groupId>
<artifactId>checker</artifactId>
<version>2.3.1</version>
</dependency>
<dependency>
<groupId>org.checkerframework</groupId>
<artifactId>jdk8</artifactId>
<version>2.3.1</version>
</dependency>
<!-- The Type Annotations compiler. Uncomment if using annotations in comments. -->
<dependency>
<groupId>org.checkerframework</groupId>
<artifactId>compiler</artifactId>
<version>2.3.1</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<!-- This plugin will set properties values using dependency information -->
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<goals>
<!--
Goal that sets a property pointing to the artifact file for each project dependency.
For each dependency (direct and transitive) a project property will be set which
follows the:
groupId:artifactId:type:[classifier]
form and contains the path to the resolved artifact. -->
<goal>properties</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.6.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<!-- Uncomment the following line to use the type annotations compiler. -->
<!-- <fork>true</fork> -->
<compilerArguments>
<Xmaxerrs>10000</Xmaxerrs>
<Xmaxwarns>10000</Xmaxwarns>
</compilerArguments>
<annotationProcessors>
<!-- Add all the checkers you want to enable here -->
<annotationProcessor>org.checkerframework.checker.nullness.NullnessChecker</annotationProcessor>
<annotationProcessor>org.checkerframework.checker.interning.InterningChecker</annotationProcessor>
<annotationProcessor>org.checkerframework.checker.fenum.FenumChecker</annotationProcessor>
<annotationProcessor>org.checkerframework.checker.formatter.FormatterChecker</annotationProcessor>
<annotationProcessor>org.checkerframework.checker.regex.RegexChecker</annotationProcessor>
</annotationProcessors>
<compilerArgs>
<arg>-AprintErrorStack</arg>
<!-- location of the annotated JDK, which comes from a Maven dependency -->
<arg>-Xbootclasspath/p:${annotatedJdk}</arg>
<!--
-->
<!-- Uncomment the following line to use the type annotations compiler. -->
<!--
<arg>-J-Xbootclasspath/p:${typeAnnotationsJavac}</arg>
-->
<!-- Uncomment the following line to turn type-checking warnings into errors. -->
<arg>-Awarns</arg>
</compilerArgs>
</configuration>
</plugin>
</plugins>
</build>
</project>

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package com.baeldung.typechecker;
import org.checkerframework.checker.fenum.qual.Fenum;
//@SuppressWarnings("fenum:assignment.type.incompatible")
public class FakeNumExample {
// Here we use some String constants to represents countries.
static final @Fenum("country") String ITALY = "IT";
static final @Fenum("country") String US = "US";
static final @Fenum("country") String UNITED_KINGDOM = "UK";
// Here we use other String constants to represent planets instead.
static final @Fenum("planet") String MARS = "Mars";
static final @Fenum("planet") String EARTH = "Earth";
static final @Fenum("planet") String VENUS = "Venus";
// Now we write this method and we want to be sure that
// the String parameter has a value of a country, not that is just a String.
void greetCountries(@Fenum("country") String country) {
System.out.println("Hello " + country);
}
// Similarly we're enforcing here that the provided
// parameter is a String that represent a planet.
void greetPlanets(@Fenum("planet") String planet) {
System.out.println("Hello " + planet);
}
public static void main(String[] args) {
FakeNumExample obj = new FakeNumExample();
// This will fail because we pass a planet-String to a method that
// accept a country-String.
obj.greetCountries(MARS);
// Here the opposite happens.
obj.greetPlanets(US);
}
}

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package com.baeldung.typechecker;
public class FormatExample {
public static void main(String[] args) {
// Just enabling org.checkerframework.checker.formatter.FormatterChecker
// we can be sure at compile time that the format strings we pass to format()
// are correct. Normally we would have those errors raised just at runtime.
// All those formats are in fact wrong.
String.format("%y", 7); // error: invalid format string
String.format("%d", "a string"); // error: invalid argument type for %d
String.format("%d %s", 7); // error: missing argument for %s
String.format("%d", 7, 3); // warning: unused argument 3
String.format("{0}", 7); // warning: unused argument 7, because {0} is wrong syntax
}
}

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package com.baeldung.typechecker;
import org.checkerframework.checker.nullness.qual.KeyFor;
import java.util.HashMap;
import java.util.Map;
public class KeyForExample {
private final Map<String, String> config = new HashMap<>();
KeyForExample() {
// Here we initialize a map to store
// some config data.
config.put("url", "http://1.2.3.4");
config.put("name", "foobaz");
}
public void dumpPort() {
// Here, we want to dump the port value stored in the
// config, so we declare that this key has to be
// present in the config map.
// Obviously that will fail because such key is not present
// in the map.
@KeyFor("config") String key = "port";
System.out.println( config.get(key) );
}
}

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package com.baeldung.typechecker;
import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
import java.util.Date;
public class MonotonicNotNullExample {
// The idea is we need this field to be to lazily initialized,
// so it starts as null but once it becomes not null
// it cannot return null.
// In these cases, we can use @MonotonicNonNull
@MonotonicNonNull private Date firstCall;
public Date getFirstCall() {
if (firstCall == null) {
firstCall = new Date();
}
return firstCall;
}
public void reset() {
// This is reported as error because
// we wrongly set the field back to null.
firstCall = null;
}
}

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package com.baeldung.typechecker;
import org.checkerframework.checker.nullness.qual.NonNull;
import org.checkerframework.checker.nullness.qual.Nullable;
public class NonNullExample {
// This method's parameter is annotated in order
// to tell the pluggable type system that it can never be null.
private static int countArgs(@NonNull String[] args) {
return args.length;
}
// This method's parameter is annotated in order
// to tell the pluggable type system that it may be null.
public static void main(@Nullable String[] args) {
// Here lies a potential error,
// because we pass a potential null reference to a method
// that does not accept nulls.
// The Checker Framework will spot this problem at compile time
// instead of runtime.
System.out.println(countArgs(args));
}
}

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@ -0,0 +1,18 @@
package com.baeldung.typechecker;
import org.checkerframework.checker.regex.qual.Regex;
public class RegexExample {
// For some reason we want to be sure that this regex
// contains at least one capturing group.
// However, we do an error and we forgot to define such
// capturing group in it.
@Regex(1) private static String findNumbers = "\\d*";
public static void main(String[] args) {
String message = "My phone number is +3911223344.";
message.matches(findNumbers);
}
}

4
core-groovy/README.md Normal file
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# Groovy
## Relevant articles:

13
core-groovy/build.gradle Normal file
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group 'com.baeldung'
version '1.0-SNAPSHOT'
apply plugin: 'groovy'
repositories {
mavenCentral()
}
dependencies {
compile 'org.codehaus.groovy:groovy-all:2.5.0-alpha-1'
testCompile 'org.spockframework:spock-core:1.1-groovy-2.4'
}

128
core-groovy/pom.xml Normal file
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<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-groovy</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-modules</artifactId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<repositories>
<repository>
<id>central</id>
<url>http://jcenter.bintray.com</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>org.codehaus.groovy</groupId>
<artifactId>groovy</artifactId>
<version>2.5.0-alpha-1</version>
</dependency>
<dependency>
<groupId>org.codehaus.groovy</groupId>
<artifactId>groovy-all</artifactId>
<version>2.5.0-alpha-1</version>
</dependency>
<dependency>
<groupId>org.codehaus.groovy</groupId>
<artifactId>groovy-sql</artifactId>
<version>2.5.0-alpha-1</version>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>${junit.jupiter.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.platform</groupId>
<artifactId>junit-platform-runner</artifactId>
<version>${junit.platform.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.hsqldb</groupId>
<artifactId>hsqldb</artifactId>
<version>2.4.0</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.spockframework</groupId>
<artifactId>spock-core</artifactId>
<version>1.1-groovy-2.4</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.codehaus.gmavenplus</groupId>
<artifactId>gmavenplus-plugin</artifactId>
<version>1.6</version>
<executions>
<execution>
<goals>
<goal>addSources</goal>
<goal>addTestSources</goal>
<goal>compile</goal>
<goal>compileTests</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>${maven-surefire-plugin.version}</version>
</plugin>
<plugin>
<artifactId>maven-failsafe-plugin</artifactId>
<version>2.19.1</version>
<dependencies>
<dependency>
<groupId>org.junit.platform</groupId>
<artifactId>junit-platform-surefire-provider</artifactId>
<version>${junit.platform.version}</version>
</dependency>
</dependencies>
<executions>
<execution>
<id>junit5</id>
<goals>
<goal>integration-test</goal>
<goal>verify</goal>
</goals>
<configuration>
<includes>
<include>**/*Test5.java</include>
</includes>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<kotlin-maven-plugin.version>1.1.2</kotlin-maven-plugin.version>
<kotlin-test-junit.version>1.1.2</kotlin-test-junit.version>
<kotlin-stdlib.version>1.1.2</kotlin-stdlib.version>
<kotlin-reflect.version>1.1.2</kotlin-reflect.version>
<kotlinx.version>0.15</kotlinx.version>
<mockito-kotlin.version>1.5.0</mockito-kotlin.version>
<junit.jupiter.version>5.0.0</junit.jupiter.version>
<junit.platform.version>1.0.0</junit.platform.version>
<junit.vintage.version>4.12.0</junit.vintage.version>
<junit4.version>4.12</junit4.version>
</properties>
</project>

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package com.baeldung.json
class Account {
String id
BigDecimal value
Date createdAt
}

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package com.baeldung.json
import groovy.json.JsonGenerator
import groovy.json.JsonOutput
import groovy.json.JsonParserType
import groovy.json.JsonSlurper
class JsonParser {
Account toObject(String json) {
JsonSlurper jsonSlurper = new JsonSlurper()
jsonSlurper.parseText(json) as Account
}
Account toObjectWithIndexOverlay(String json) {
JsonSlurper jsonSlurper = new JsonSlurper(type: JsonParserType.INDEX_OVERLAY)
jsonSlurper.parseText(json) as Account
}
String toJson(Account account) {
JsonOutput.toJson(account)
}
String toJson(Account account, String dateFormat, String... fieldsToExclude) {
JsonGenerator generator = new JsonGenerator.Options()
.dateFormat(dateFormat)
.excludeFieldsByName(fieldsToExclude)
.build()
generator.toJson(account)
}
String prettyfy(String json) {
JsonOutput.prettyPrint(json)
}
}

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package com.baeldung.groovy.sql
import groovy.sql.GroovyResultSet
import groovy.sql.GroovyRowResult
import groovy.sql.Sql
import groovy.transform.CompileStatic
import static org.junit.Assert.*
import org.junit.Test
class SqlTest {
final Map dbConnParams = [url: 'jdbc:hsqldb:mem:testDB', user: 'sa', password: '', driver: 'org.hsqldb.jdbc.JDBCDriver']
@Test
void whenNewSqlInstance_thenDbIsAccessed() {
def sql = Sql.newInstance(dbConnParams)
sql.close()
sql.close()
}
@Test
void whenTableDoesNotExist_thenSelectFails() {
try {
Sql.withInstance(dbConnParams) { Sql sql ->
sql.eachRow('select * from PROJECT') {}
}
fail("An exception should have been thrown")
} catch (ignored) {
//Ok
}
}
@Test
void whenTableCreated_thenSelectIsPossible() {
Sql.withInstance(dbConnParams) { Sql sql ->
def result = sql.execute 'create table PROJECT_1 (id integer not null, name varchar(50), url varchar(100))'
assertEquals(0, sql.updateCount)
assertFalse(result)
result = sql.execute('select * from PROJECT_1')
assertTrue(result)
}
}
@Test
void whenIdentityColumn_thenInsertReturnsNewId() {
Sql.withInstance(dbConnParams) { Sql sql ->
sql.execute 'create table PROJECT_2 (ID IDENTITY, NAME VARCHAR (50), URL VARCHAR (100))'
def ids = sql.executeInsert("INSERT INTO PROJECT_2 (NAME, URL) VALUES ('tutorials', 'github.com/eugenp/tutorials')")
assertEquals(0, ids[0][0])
ids = sql.executeInsert("INSERT INTO PROJECT_2 (NAME, URL) VALUES ('REST with Spring', 'github.com/eugenp/REST-With-Spring')")
assertEquals(1, ids[0][0])
}
}
@Test
void whenUpdate_thenNumberOfAffectedRows() {
Sql.withInstance(dbConnParams) { Sql sql ->
sql.execute 'create table PROJECT_3 (ID IDENTITY, NAME VARCHAR (50), URL VARCHAR (100))'
sql.executeInsert("INSERT INTO PROJECT_3 (NAME, URL) VALUES ('tutorials', 'github.com/eugenp/tutorials')")
sql.executeInsert("INSERT INTO PROJECT_3 (NAME, URL) VALUES ('REST with Spring', 'github.com/eugenp/REST-With-Spring')")
def count = sql.executeUpdate("UPDATE PROJECT_3 SET URL = 'https://' + URL")
assertEquals(2, count)
}
}
@Test
void whenEachRow_thenResultSetHasProperties() {
Sql.withInstance(dbConnParams) { Sql sql ->
sql.execute 'create table PROJECT_4 (ID IDENTITY, NAME VARCHAR (50), URL VARCHAR (100))'
sql.executeInsert("INSERT INTO PROJECT_4 (NAME, URL) VALUES ('tutorials', 'https://github.com/eugenp/tutorials')")
sql.executeInsert("INSERT INTO PROJECT_4 (NAME, URL) VALUES ('REST with Spring', 'https://github.com/eugenp/REST-With-Spring')")
sql.eachRow("SELECT * FROM PROJECT_4") { GroovyResultSet rs ->
assertNotNull(rs.name)
assertNotNull(rs.url)
assertNotNull(rs[0])
assertNotNull(rs[1])
assertNotNull(rs[2])
assertEquals(rs.name, rs['name'])
assertEquals(rs.url, rs['url'])
}
}
}
@Test
void whenPagination_thenSubsetIsReturned() {
Sql.withInstance(dbConnParams) { Sql sql ->
sql.execute 'create table PROJECT_5 (ID IDENTITY, NAME VARCHAR (50), URL VARCHAR (100))'
sql.executeInsert("INSERT INTO PROJECT_5 (NAME, URL) VALUES ('tutorials', 'github.com/eugenp/tutorials')")
sql.executeInsert("INSERT INTO PROJECT_5 (NAME, URL) VALUES ('REST with Spring', 'github.com/eugenp/REST-With-Spring')")
def rows = sql.rows('SELECT * FROM PROJECT_5 ORDER BY NAME', 1, 1)
assertEquals(1, rows.size())
assertEquals('REST with Spring', rows[0].name)
}
}
@Test
void whenParameters_thenReplacement() {
Sql.withInstance(dbConnParams) { Sql sql ->
sql.execute 'create table PROJECT_6 (ID IDENTITY, NAME VARCHAR (50), URL VARCHAR (100))'
sql.execute('INSERT INTO PROJECT_6 (NAME, URL) VALUES (?, ?)', 'tutorials', 'github.com/eugenp/tutorials')
sql.execute("INSERT INTO PROJECT_6 (NAME, URL) VALUES (:name, :url)", [name: 'REST with Spring', url: 'github.com/eugenp/REST-With-Spring'])
def rows = sql.rows("SELECT * FROM PROJECT_6 WHERE NAME = 'tutorials'")
assertEquals(1, rows.size())
rows = sql.rows("SELECT * FROM PROJECT_6 WHERE NAME = 'REST with Spring'")
assertEquals(1, rows.size())
}
}
@Test
void whenParametersInGString_thenReplacement() {
Sql.withInstance(dbConnParams) { Sql sql ->
sql.execute 'create table PROJECT_7 (ID IDENTITY, NAME VARCHAR (50), URL VARCHAR (100))'
sql.execute "INSERT INTO PROJECT_7 (NAME, URL) VALUES (${'tutorials'}, ${'github.com/eugenp/tutorials'})"
def name = 'REST with Spring'
def url = 'github.com/eugenp/REST-With-Spring'
sql.execute "INSERT INTO PROJECT_7 (NAME, URL) VALUES (${name}, ${url})"
def rows = sql.rows("SELECT * FROM PROJECT_7 WHERE NAME = 'tutorials'")
assertEquals(1, rows.size())
rows = sql.rows("SELECT * FROM PROJECT_7 WHERE NAME = 'REST with Spring'")
assertEquals(1, rows.size())
}
}
@Test
void whenTransactionRollback_thenNoDataInserted() {
Sql.withInstance(dbConnParams) { Sql sql ->
sql.withTransaction {
sql.execute 'create table PROJECT_8 (ID IDENTITY, NAME VARCHAR (50), URL VARCHAR (100))'
sql.executeInsert("INSERT INTO PROJECT_8 (NAME, URL) VALUES ('tutorials', 'https://github.com/eugenp/tutorials')")
sql.executeInsert("INSERT INTO PROJECT_8 (NAME, URL) VALUES ('REST with Spring', 'https://github.com/eugenp/REST-With-Spring')")
sql.rollback()
def rows = sql.rows("SELECT * FROM PROJECT_8")
assertEquals(0, rows.size())
}
}
}
@Test
void whenTransactionRollbackThenCommit_thenOnlyLastInserted() {
Sql.withInstance(dbConnParams) { Sql sql ->
sql.withTransaction {
sql.execute 'create table PROJECT_9 (ID IDENTITY, NAME VARCHAR (50), URL VARCHAR (100))'
sql.executeInsert("INSERT INTO PROJECT_9 (NAME, URL) VALUES ('tutorials', 'https://github.com/eugenp/tutorials')")
sql.rollback()
sql.executeInsert("INSERT INTO PROJECT_9 (NAME, URL) VALUES ('REST with Spring', 'https://github.com/eugenp/REST-With-Spring')")
sql.rollback()
sql.executeInsert("INSERT INTO PROJECT_9 (NAME, URL) VALUES ('tutorials', 'https://github.com/eugenp/tutorials')")
sql.executeInsert("INSERT INTO PROJECT_9 (NAME, URL) VALUES ('REST with Spring', 'https://github.com/eugenp/REST-With-Spring')")
}
def rows = sql.rows("SELECT * FROM PROJECT_9")
assertEquals(2, rows.size())
}
}
@Test
void whenException_thenTransactionIsRolledBack() {
Sql.withInstance(dbConnParams) { Sql sql ->
try {
sql.withTransaction {
sql.execute 'create table PROJECT_10 (ID IDENTITY, NAME VARCHAR (50), URL VARCHAR (100))'
sql.executeInsert("INSERT INTO PROJECT_10 (NAME, URL) VALUES ('tutorials', 'https://github.com/eugenp/tutorials')")
throw new Exception('rollback')
}
} catch (ignored) {}
def rows = sql.rows("SELECT * FROM PROJECT_10")
assertEquals(0, rows.size())
}
}
@Test
void givenCachedConnection_whenException_thenDataIsPersisted() {
Sql.withInstance(dbConnParams) { Sql sql ->
try {
sql.cacheConnection {
sql.execute 'create table PROJECT_11 (ID IDENTITY, NAME VARCHAR (50), URL VARCHAR (100))'
sql.executeInsert("INSERT INTO PROJECT_11 (NAME, URL) VALUES ('tutorials', 'https://github.com/eugenp/tutorials')")
throw new Exception('This does not rollback')
}
} catch (ignored) {}
def rows = sql.rows("SELECT * FROM PROJECT_11")
assertEquals(1, rows.size())
}
}
/*@Test
void whenModifyResultSet_thenDataIsChanged() {
Sql.withInstance(dbConnParams) { Sql sql ->
sql.execute 'create table PROJECT_5 (ID IDENTITY, NAME VARCHAR (50), URL VARCHAR (100))'
sql.executeInsert("INSERT INTO PROJECT_5 (NAME, URL) VALUES ('tutorials', 'github.com/eugenp/tutorials')")
sql.executeInsert("INSERT INTO PROJECT_5 (NAME, URL) VALUES ('REST with Spring', 'github.com/eugenp/REST-With-Spring')")
sql.eachRow("SELECT * FROM PROJECT_5 FOR UPDATE ") { GroovyResultSet rs ->
rs['name'] = "The great ${rs.name}!" as String
rs.updateRow()
}
sql.eachRow("SELECT * FROM PROJECT_5") { GroovyResultSet rs ->
assertTrue(rs.name.startsWith('The great '))
}
}
}*/
}

View File

@ -0,0 +1,80 @@
package com.baeldung.json
import spock.lang.Specification
import java.text.SimpleDateFormat
class JsonParserTest extends Specification {
JsonParser jsonParser
void setup () {
jsonParser = new JsonParser()
}
def 'Should parse to Account given Json String' () {
given:
def json = '{"id":"1234","value":15.6}'
when:
def account = jsonParser.toObject(json)
then:
account
account instanceof Account
account.id == '1234'
account.value == 15.6
}
def 'Should parse to Account given Json String with date property' () {
given:
def json = '{"id":"1234","value":15.6,"createdAt":"2018-01-01T00:00:00+0000"}'
when:
def account = jsonParser.toObjectWithIndexOverlay(json)
then:
account
account instanceof Account
account.id == '1234'
account.value == 15.6
println account.createdAt
account.createdAt == Date.parse('yyyy-MM-dd', '2018-01-01')
}
def 'Should parse to Json given an Account object' () {
given:
Account account = new Account(
id: '123',
value: 15.6,
createdAt: new SimpleDateFormat('MM/dd/yyyy').parse('01/01/2018')
)
when:
def json = jsonParser.toJson(account)
then:
json
json == '{"value":15.6,"createdAt":"2018-01-01T00:00:00+0000","id":"123"}'
}
def 'Should parse to Json given an Account object, a date format and fields to exclude' () {
given:
Account account = new Account(
id: '123',
value: 15.6,
createdAt: new SimpleDateFormat('MM/dd/yyyy').parse('01/01/2018')
)
when:
def json = jsonParser.toJson(account, 'MM/dd/yyyy', 'value')
then:
json
json == '{"createdAt":"01/01/2018","id":"123"}'
}
def 'Should prettify given a json string' () {
given:
String json = '{"value":15.6,"createdAt":"01/01/2018","id":"123456"}'
when:
def jsonPretty = jsonParser.prettyfy(json)
then:
jsonPretty
jsonPretty == '{\n "value": 15.6,\n "createdAt": "01/01/2018",\n "id": "123456"\n}'
}
}

View File

@ -40,3 +40,4 @@
- [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)
- [Shuffling Collections In Java](http://www.baeldung.com/java-shuffle-collection)

View File

@ -0,0 +1,70 @@
package com.baeldung.shufflingcollections;
import org.junit.Test;
import java.util.*;
import java.util.stream.Collectors;
import static org.assertj.core.api.Assertions.assertThat;
public class ShufflingCollectionsUnitTest {
@Test
public void whenShufflingList_thenListIsShuffled() {
List<String> students = Arrays.asList("Foo", "Bar", "Baz", "Qux");
System.out.println("List before shuffling:");
System.out.println(students);
Collections.shuffle(students);
System.out.println("List after shuffling:");
System.out.println(students);
}
@Test
public void whenShufflingMapEntries_thenValuesAreShuffled() {
Map<Integer, String> studentsById = new HashMap<>();
studentsById.put(1, "Foo");
studentsById.put(2, "Bar");
studentsById.put(3, "Baz");
studentsById.put(4, "Qux");
System.out.println("Students before shuffling:");
System.out.println(studentsById.values());
List<Map.Entry<Integer, String>> shuffledStudentEntries = new ArrayList<>(studentsById.entrySet());
Collections.shuffle(shuffledStudentEntries);
List<String> shuffledStudents = shuffledStudentEntries.stream()
.map(Map.Entry::getValue)
.collect(Collectors.toList());
System.out.println("Students after shuffling");
System.out.println(shuffledStudents);
}
@Test
public void whenShufflingSet_thenElementsAreShuffled() {
Set<String> students = new HashSet<>(Arrays.asList("Foo", "Bar", "Baz", "Qux"));
System.out.println("Set before shuffling:");
System.out.println(students);
List<String> studentList = new ArrayList<>(students);
Collections.shuffle(studentList);
System.out.println("Shuffled set elements:");
System.out.println(studentList);
}
@Test
public void whenShufflingWithSameRandomness_thenElementsAreShuffledDeterministically() {
List<String> students_1 = Arrays.asList("Foo", "Bar", "Baz", "Qux");
List<String> students_2 = Arrays.asList("Foo", "Bar", "Baz", "Qux");
Collections.shuffle(students_1, new Random(5));
Collections.shuffle(students_2, new Random(5));
assertThat(students_1).isEqualTo(students_2);
}
}

View File

@ -0,0 +1,17 @@
package com.baeldung.java9.methodhandles;
public class Book {
String id;
String title;
public Book(String id, String title) {
this.id = id;
this.title = title;
}
@SuppressWarnings("unused")
private String formatBook() {
return id + " > " + title;
}
}

View File

@ -1,126 +0,0 @@
package com.baeldung.java9.httpclient;
import static java.net.HttpURLConnection.HTTP_OK;
import static org.junit.Assert.assertTrue;
import java.io.IOException;
import java.net.CookieManager;
import java.net.CookiePolicy;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.http.HttpClient;
import java.net.http.HttpHeaders;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.security.NoSuchAlgorithmException;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLParameters;
import org.junit.Before;
import org.junit.Test;
public class SimpleHttpRequestsUnitTest {
private URI httpURI;
@Before
public void init() throws URISyntaxException {
httpURI = new URI("http://www.baeldung.com/");
}
@Test
public void quickGet() throws IOException, InterruptedException, URISyntaxException {
HttpRequest request = HttpRequest.create(httpURI).GET();
HttpResponse response = request.response();
int responseStatusCode = response.statusCode();
String responseBody = response.body(HttpResponse.asString());
assertTrue("Get response status code is bigger then 400", responseStatusCode < 400);
}
@Test
public void asynchronousGet() throws URISyntaxException, IOException, InterruptedException, ExecutionException {
HttpRequest request = HttpRequest.create(httpURI).GET();
long before = System.currentTimeMillis();
CompletableFuture<HttpResponse> futureResponse = request.responseAsync();
futureResponse.thenAccept(response -> {
String responseBody = response.body(HttpResponse.asString());
});
HttpResponse resp = futureResponse.get();
HttpHeaders hs = resp.headers();
assertTrue("There should be more then 1 header.", hs.map().size() > 1);
}
@Test
public void postMehtod() throws URISyntaxException, IOException, InterruptedException {
HttpRequest.Builder requestBuilder = HttpRequest.create(httpURI);
requestBuilder.body(HttpRequest.fromString("param1=foo,param2=bar")).followRedirects(HttpClient.Redirect.SECURE);
HttpRequest request = requestBuilder.POST();
HttpResponse response = request.response();
int statusCode = response.statusCode();
assertTrue("HTTP return code", statusCode == HTTP_OK);
}
@Test
public void configureHttpClient() throws NoSuchAlgorithmException, URISyntaxException, IOException, InterruptedException {
CookieManager cManager = new CookieManager();
cManager.setCookiePolicy(CookiePolicy.ACCEPT_ORIGINAL_SERVER);
SSLParameters sslParam = new SSLParameters(new String[] { "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256" }, new String[] { "TLSv1.2" });
HttpClient.Builder hcBuilder = HttpClient.create();
hcBuilder.cookieManager(cManager).sslContext(SSLContext.getDefault()).sslParameters(sslParam);
HttpClient httpClient = hcBuilder.build();
HttpRequest.Builder reqBuilder = httpClient.request(new URI("https://www.facebook.com"));
HttpRequest request = reqBuilder.followRedirects(HttpClient.Redirect.ALWAYS).GET();
HttpResponse response = request.response();
int statusCode = response.statusCode();
assertTrue("HTTP return code", statusCode == HTTP_OK);
}
SSLParameters getDefaultSSLParameters() throws NoSuchAlgorithmException {
SSLParameters sslP1 = SSLContext.getDefault().getSupportedSSLParameters();
String[] proto = sslP1.getApplicationProtocols();
String[] cifers = sslP1.getCipherSuites();
System.out.println(printStringArr(proto));
System.out.println(printStringArr(cifers));
return sslP1;
}
String printStringArr(String... args) {
if (args == null) {
return null;
}
StringBuilder sb = new StringBuilder();
for (String s : args) {
sb.append(s);
sb.append("\n");
}
return sb.toString();
}
String printHeaders(HttpHeaders h) {
if (h == null) {
return null;
}
StringBuilder sb = new StringBuilder();
Map<String, List<String>> hMap = h.map();
for (String k : hMap.keySet()) {
sb.append(k).append(":");
List<String> l = hMap.get(k);
if (l != null) {
l.forEach(s -> {
sb.append(s).append(",");
});
}
sb.append("\n");
}
return sb.toString();
}
}

View File

@ -0,0 +1,152 @@
package com.baeldung.java9.methodhandles;
import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.*;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.invoke.WrongMethodTypeException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.List;
import org.junit.Test;
/**
* Test case for the {@link MethodHandles} API
*/
public class MethodHandlesTest {
@Test
public void givenConcatMethodHandle_whenInvoked_thenCorrectlyConcatenated() throws Throwable {
MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
MethodType mt = MethodType.methodType(String.class, String.class);
MethodHandle concatMH = publicLookup.findVirtual(String.class, "concat", mt);
String output = (String) concatMH.invoke("Effective ", "Java");
assertEquals("Effective Java", output);
}
@Test
public void givenAsListMethodHandle_whenInvokingWithArguments_thenCorrectlyInvoked() throws Throwable {
MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
MethodType mt = MethodType.methodType(List.class, Object[].class);
MethodHandle asListMH = publicLookup.findStatic(Arrays.class, "asList", mt);
List<Integer> list = (List<Integer>) asListMH.invokeWithArguments(1, 2);
assertThat(Arrays.asList(1, 2), is(list));
}
@Test
public void givenConstructorMethodHandle_whenInvoked_thenObjectCreatedCorrectly() throws Throwable {
MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
MethodType mt = MethodType.methodType(void.class, String.class);
MethodHandle newIntegerMH = publicLookup.findConstructor(Integer.class, mt);
Integer integer = (Integer) newIntegerMH.invoke("1");
assertEquals(1, integer.intValue());
}
@Test
public void givenAFieldWithoutGetter_whenCreatingAGetter_thenCorrectlyInvoked() throws Throwable {
MethodHandles.Lookup lookup = MethodHandles.lookup();
MethodHandle getTitleMH = lookup.findGetter(Book.class, "title", String.class);
Book book = new Book("ISBN-1234", "Effective Java");
assertEquals("Effective Java", getTitleMH.invoke(book));
}
@Test
public void givenPrivateMethod_whenCreatingItsMethodHandle_thenCorrectlyInvoked() throws Throwable {
MethodHandles.Lookup lookup = MethodHandles.lookup();
Method formatBookMethod = Book.class.getDeclaredMethod("formatBook");
formatBookMethod.setAccessible(true);
MethodHandle formatBookMH = lookup.unreflect(formatBookMethod);
Book book = new Book("ISBN-123", "Java in Action");
assertEquals("ISBN-123 > Java in Action", formatBookMH.invoke(book));
}
@Test
public void givenReplaceMethod_whenUsingReflectionAndInvoked_thenCorrectlyReplaced() throws Throwable {
Method replaceMethod = String.class.getMethod("replace", char.class, char.class);
String string = (String) replaceMethod.invoke("jovo", 'o', 'a');
assertEquals("java", string);
}
@Test
public void givenReplaceMethodHandle_whenInvoked_thenCorrectlyReplaced() throws Throwable {
MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
MethodType mt = MethodType.methodType(String.class, char.class, char.class);
MethodHandle replaceMH = publicLookup.findVirtual(String.class, "replace", mt);
String replacedString = (String) replaceMH.invoke("jovo", Character.valueOf('o'), 'a');
assertEquals("java", replacedString);
}
@Test
public void givenReplaceMethodHandle_whenInvokingExact_thenCorrectlyReplaced() throws Throwable {
MethodHandles.Lookup lookup = MethodHandles.lookup();
MethodType mt = MethodType.methodType(String.class, char.class, char.class);
MethodHandle replaceMH = lookup.findVirtual(String.class, "replace", mt);
String s = (String) replaceMH.invokeExact("jovo", 'o', 'a');
assertEquals("java", s);
}
@Test
public void givenSumMethodHandle_whenInvokingExact_thenSumIsCorrect() throws Throwable {
MethodHandles.Lookup lookup = MethodHandles.lookup();
MethodType mt = MethodType.methodType(int.class, int.class, int.class);
MethodHandle sumMH = lookup.findStatic(Integer.class, "sum", mt);
int sum = (int) sumMH.invokeExact(1, 11);
assertEquals(12, sum);
}
@Test(expected = WrongMethodTypeException.class)
public void givenSumMethodHandleAndIncompatibleArguments_whenInvokingExact_thenException() throws Throwable {
MethodHandles.Lookup lookup = MethodHandles.lookup();
MethodType mt = MethodType.methodType(int.class, int.class, int.class);
MethodHandle sumMH = lookup.findStatic(Integer.class, "sum", mt);
sumMH.invokeExact(Integer.valueOf(1), 11);
}
@Test
public void givenSpreadedEqualsMethodHandle_whenInvokedOnArray_thenCorrectlyEvaluated() throws Throwable {
MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
MethodType mt = MethodType.methodType(boolean.class, Object.class);
MethodHandle equalsMH = publicLookup.findVirtual(String.class, "equals", mt);
MethodHandle methodHandle = equalsMH.asSpreader(Object[].class, 2);
assertTrue((boolean) methodHandle.invoke(new Object[] { "java", "java" }));
assertFalse((boolean) methodHandle.invoke(new Object[] { "java", "jova" }));
}
@Test
public void givenConcatMethodHandle_whenBindToAString_thenCorrectlyConcatenated() throws Throwable {
MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
MethodType mt = MethodType.methodType(String.class, String.class);
MethodHandle concatMH = publicLookup.findVirtual(String.class, "concat", mt);
MethodHandle bindedConcatMH = concatMH.bindTo("Hello ");
assertEquals("Hello World!", bindedConcatMH.invoke("World!"));
}
}

View File

@ -0,0 +1,31 @@
package com.baeldung.concurrent.threadlifecycle;
public class BlockedState {
public static void main(String[] args) throws InterruptedException {
Thread t1 = new Thread(new DemoThreadB());
Thread t2 = new Thread(new DemoThreadB());
t1.start();
t2.start();
Thread.sleep(1000);
System.out.println(t2.getState());
System.exit(0);
}
}
class DemoThreadB implements Runnable {
@Override
public void run() {
commonResource();
}
public static synchronized void commonResource() {
while(true) {
// Infinite loop to mimic heavy processing
// Thread 't1' won't leave this method
// when Thread 't2' enters this
}
}
}

View File

@ -0,0 +1,14 @@
package com.baeldung.concurrent.threadlifecycle;
public class NewState implements Runnable {
public static void main(String[] args) {
Runnable runnable = new NewState();
Thread t = new Thread(runnable);
System.out.println(t.getState());
}
@Override
public void run() {
}
}

View File

@ -0,0 +1,15 @@
package com.baeldung.concurrent.threadlifecycle;
public class RunnableState implements Runnable {
public static void main(String[] args) {
Runnable runnable = new NewState();
Thread t = new Thread(runnable);
t.start();
System.out.println(t.getState());
}
@Override
public void run() {
}
}

View File

@ -0,0 +1,15 @@
package com.baeldung.concurrent.threadlifecycle;
public class TerminatedState implements Runnable {
public static void main(String[] args) throws InterruptedException {
Thread t1 = new Thread(new TerminatedState());
t1.start();
Thread.sleep(1000);
System.out.println(t1.getState());
}
@Override
public void run() {
// No processing in this block
}
}

View File

@ -0,0 +1,25 @@
package com.baeldung.concurrent.threadlifecycle;
public class TimedWaitingState {
public static void main(String[] args) throws InterruptedException {
DemoThread obj1 = new DemoThread();
Thread t1 = new Thread(obj1);
t1.start();
// The following sleep will give enough time for ThreadScheduler
// to start processing of thread t1
Thread.sleep(1000);
System.out.println(t1.getState());
}
}
class DemoThread implements Runnable {
@Override
public void run() {
try {
Thread.sleep(5000);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
e.printStackTrace();
}
}
}

View File

@ -0,0 +1,35 @@
package com.baeldung.concurrent.threadlifecycle;
public class WaitingState implements Runnable {
public static Thread t1;
public static void main(String[] args) {
t1 = new Thread(new WaitingState());
t1.start();
}
public void run() {
Thread t2 = new Thread(new DemoThreadWS());
t2.start();
try {
t2.join();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
e.printStackTrace();
}
}
}
class DemoThreadWS implements Runnable {
public void run() {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
e.printStackTrace();
}
System.out.println(WaitingState.t1.getState());
}
}

View File

@ -10,7 +10,7 @@ import org.junit.Test;
import com.jayway.awaitility.Awaitility;
public class StopThreadTest {
public class StopThreadManualTest {
@Test
public void whenStoppedThreadIsStopped() throws InterruptedException {

View File

@ -127,3 +127,5 @@
- [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)
- [Compiling Java *.class Files with javac](http://www.baeldung.com/javac)
- [Method Overloading and Overriding in Java](http://www.baeldung.com/java-method-overload-override)

View File

@ -78,6 +78,11 @@
<artifactId>jackson-databind</artifactId>
<version>${jackson.version}</version>
</dependency>
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
<version>${gson.version}</version>
</dependency>
<!-- logging -->
<dependency>
@ -468,6 +473,7 @@
<properties>
<!-- marshalling -->
<jackson.version>2.8.5</jackson.version>
<gson.version>2.8.2</gson.version>
<!-- logging -->
<org.slf4j.version>1.7.21</org.slf4j.version>

View File

@ -0,0 +1,13 @@
package com.baeldung.casting;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class Animal {
private static final Logger LOGGER = LoggerFactory.getLogger(Animal.class);
public void eat() {
LOGGER.info("animal is eating");
}
}

View File

@ -0,0 +1,23 @@
package com.baeldung.casting;
import java.util.List;
public class AnimalFeeder {
public void feed(List<Animal> animals) {
animals.forEach(animal -> {
animal.eat();
if (animal instanceof Cat) {
((Cat) animal).meow();
}
});
}
public void uncheckedFeed(List<Animal> animals) {
animals.forEach(animal -> {
animal.eat();
((Cat) animal).meow();
});
}
}

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@ -0,0 +1,16 @@
package com.baeldung.casting;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class Cat extends Animal implements Mew {
private static final Logger LOGGER = LoggerFactory.getLogger(Cat.class);
public void eat() {
LOGGER.info("cat is eating");
}
public void meow() {
LOGGER.info("meow");
}
}

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@ -0,0 +1,12 @@
package com.baeldung.casting;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class Dog extends Animal {
private static final Logger LOGGER = LoggerFactory.getLogger(Dog.class);
public void eat() {
LOGGER.info("dog is eating");
}
}

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@ -0,0 +1,5 @@
package com.baeldung.casting;
public interface Mew {
public void meow();
}

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@ -0,0 +1,29 @@
package com.baeldung.classloader;
import java.io.*;
public class CustomClassLoader extends ClassLoader {
public Class getClass(String name) throws ClassNotFoundException {
byte[] b = loadClassFromFile(name);
return defineClass(name, b, 0, b.length);
}
private byte[] loadClassFromFile(String fileName) {
InputStream inputStream = getClass().getClassLoader().getResourceAsStream(
fileName.replace('.', File.separatorChar) + ".class");
byte[] buffer;
ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
int nextValue = 0;
try {
while ( (nextValue = inputStream.read()) != -1 ) {
byteStream.write(nextValue);
}
} catch (IOException e) {
e.printStackTrace();
}
buffer = byteStream.toByteArray();
return buffer;
}
}

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@ -0,0 +1,22 @@
package com.baeldung.classloader;
import com.sun.javafx.util.Logging;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
public class PrintClassLoader {
public void printClassLoaders() throws ClassNotFoundException {
System.out.println("Classloader of this class:" + PrintClassLoader.class.getClassLoader());
System.out.println("Classloader of Logging:" + Logging.class.getClassLoader());
System.out.println("Classloader of ArrayList:" + ArrayList.class.getClassLoader());
}
}

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@ -0,0 +1,59 @@
package com.baeldung.deepcopy;
import java.io.Serializable;
public class Address implements Serializable, Cloneable {
@Override
public Object clone() {
try {
return (Address) super.clone();
} catch (CloneNotSupportedException e) {
return new Address(this.street, this.getCity(), this.getCountry());
}
}
private static final long serialVersionUID = 1740913841244949416L;
private String street;
private String city;
private String country;
public Address(Address that) {
this(that.getStreet(), that.getCity(), that.getCountry());
}
public Address(String street, String city, String country) {
this.street = street;
this.city = city;
this.country = country;
}
public Address() {
}
public String getStreet() {
return street;
}
public String getCity() {
return city;
}
public String getCountry() {
return country;
}
public void setStreet(String street) {
this.street = street;
}
public void setCity(String city) {
this.city = city;
}
public void setCountry(String country) {
this.country = country;
}
}

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@ -0,0 +1,48 @@
package com.baeldung.deepcopy;
import java.io.Serializable;
public class User implements Serializable, Cloneable {
private static final long serialVersionUID = -3427002229954777557L;
private String firstName;
private String lastName;
private Address address;
public User(String firstName, String lastName, Address address) {
this.firstName = firstName;
this.lastName = lastName;
this.address = address;
}
public User(User that) {
this(that.getFirstName(), that.getLastName(), new Address(that.getAddress()));
}
public User() {
}
@Override
public Object clone() {
User user;
try {
user = (User) super.clone();
} catch (CloneNotSupportedException e) {
user = new User(this.getFirstName(), this.getLastName(), this.getAddress());
}
user.address = (Address) this.address.clone();
return user;
}
public String getFirstName() {
return firstName;
}
public String getLastName() {
return lastName;
}
public Address getAddress() {
return address;
}
}

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@ -0,0 +1,13 @@
package com.baeldung.designpatterns.chainofresponsibility;
public abstract class AuthenticationProcessor {
// next element in chain or responsibility
public AuthenticationProcessor nextProcessor;
public AuthenticationProcessor(AuthenticationProcessor nextProcessor) {
this.nextProcessor = nextProcessor;
}
public abstract boolean isAuthorized(AuthenticationProvider authProvider);
}

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@ -0,0 +1,5 @@
package com.baeldung.designpatterns.chainofresponsibility;
public interface AuthenticationProvider {
}

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@ -0,0 +1,21 @@
package com.baeldung.designpatterns.chainofresponsibility;
public class OAuthAuthenticationProcessor extends AuthenticationProcessor {
public OAuthAuthenticationProcessor(AuthenticationProcessor nextProcessor) {
super(nextProcessor);
}
@Override
public boolean isAuthorized(AuthenticationProvider authProvider) {
if (authProvider instanceof OAuthTokenProvider) {
return Boolean.TRUE;
} else if (nextProcessor != null) {
return nextProcessor.isAuthorized(authProvider);
} else {
return Boolean.FALSE;
}
}
}

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@ -0,0 +1,5 @@
package com.baeldung.designpatterns.chainofresponsibility;
public class OAuthTokenProvider implements AuthenticationProvider {
}

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@ -0,0 +1,5 @@
package com.baeldung.designpatterns.chainofresponsibility;
public class SamlAuthenticationProvider implements AuthenticationProvider {
}

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@ -0,0 +1,20 @@
package com.baeldung.designpatterns.chainofresponsibility;
public class UsernamePasswordAuthenticationProcessor extends AuthenticationProcessor {
public UsernamePasswordAuthenticationProcessor(AuthenticationProcessor nextProcessor) {
super(nextProcessor);
}
@Override
public boolean isAuthorized(AuthenticationProvider authProvider) {
if (authProvider instanceof UsernamePasswordProvider) {
return Boolean.TRUE;
} else if (nextProcessor != null) {
return nextProcessor.isAuthorized(authProvider);
} else {
return Boolean.FALSE;
}
}
}

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@ -0,0 +1,5 @@
package com.baeldung.designpatterns.chainofresponsibility;
public class UsernamePasswordProvider implements AuthenticationProvider {
}

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@ -0,0 +1,85 @@
package com.baeldung.designpatterns.flyweight;
import java.awt.Color;
import javax.annotation.concurrent.Immutable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Represents a car. This class is immutable.
*
* @author Donato Rimenti
*/
@Immutable
public class Car implements Vehicle {
/**
* Logger.
*/
private final static Logger LOG = LoggerFactory.getLogger(Car.class);
/**
* The car's engine.
*/
private Engine engine;
/**
* The car's color.
*/
private Color color;
/**
* Instantiates a new Car.
*
* @param engine
* the {@link #engine}
* @param color
* the {@link #color}
*/
public Car(Engine engine, Color color) {
this.engine = engine;
this.color = color;
// Building a new car is a very expensive operation!
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
LOG.error("Error while creating a new car", e);
}
}
/*
* (non-Javadoc)
*
* @see com.baeldung.designpatterns.flyweight.Vehicle#start()
*/
@Override
public void start() {
LOG.info("Car is starting!");
engine.start();
}
/*
* (non-Javadoc)
*
* @see com.baeldung.designpatterns.flyweight.Vehicle#stop()
*/
@Override
public void stop() {
LOG.info("Car is stopping!");
engine.stop();
}
/*
* (non-Javadoc)
*
* @see com.baeldung.designpatterns.flyweight.Vehicle#getColor()
*/
@Override
public Color getColor() {
return this.color;
}
}

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@ -0,0 +1,31 @@
package com.baeldung.designpatterns.flyweight;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Engine for a vehicle.
*
* @author Donato Rimenti
*/
public class Engine {
/**
* Logger.
*/
private final static Logger LOG = LoggerFactory.getLogger(Engine.class);
/**
* Starts the engine.
*/
public void start() {
LOG.info("Engine is starting!");
}
/**
* Stops the engine.
*/
public void stop() {
LOG.info("Engine is stopping!");
}
}

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@ -0,0 +1,29 @@
package com.baeldung.designpatterns.flyweight;
import java.awt.Color;
/**
* Interface for a vehicle.
*
* @author Donato Rimenti
*/
public interface Vehicle {
/**
* Starts the vehicle.
*/
public void start();
/**
* Stops the vehicle.
*/
public void stop();
/**
* Gets the color of the vehicle.
*
* @return the color of the vehicle
*/
public Color getColor();
}

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@ -0,0 +1,45 @@
package com.baeldung.designpatterns.flyweight;
import java.awt.Color;
import java.util.HashMap;
import java.util.Map;
/**
* Factory which implements the Flyweight pattern to return an existing vehicle
* if present or a new one otherwise.
*
* @author Donato Rimenti
*/
public class VehicleFactory {
/**
* Stores the already created vehicles.
*/
private static Map<Color, Vehicle> vehiclesCache = new HashMap<Color, Vehicle>();
/**
* Private constructor to prevent this class instantiation.
*/
private VehicleFactory() {
}
/**
* Returns a vehicle of the same color passed as argument. If that vehicle
* was already created by this factory, that vehicle is returned, otherwise
* a new one is created and returned.
*
* @param color
* the color of the vehicle to return
* @return a vehicle of the specified color
*/
public static Vehicle createVehicle(Color color) {
// Looks for the requested vehicle into the cache.
// If the vehicle doesn't exist, a new one is created.
Vehicle newVehicle = vehiclesCache.computeIfAbsent(color, newColor -> {
// Creates the new car.
Engine newEngine = new Engine();
return new Car(newEngine, newColor);
});
return newVehicle;
}
}

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@ -0,0 +1,43 @@
package com.baeldung.inheritance;
public class ArmoredCar extends Car implements Floatable, Flyable{
private int bulletProofWindows;
private String model;
public void remoteStartCar() {
// this vehicle can be started by using a remote control
}
public String registerModel() {
return model;
}
public String getAValue() {
return super.model; // returns value of model defined in base class Car
// return this.model; // will return value of model defined in ArmoredCar
// return model; // will return value of model defined in ArmoredCar
}
public static String msg() {
// return super.msg(); // this won't compile.
return "ArmoredCar";
}
@Override
public void floatOnWater() {
System.out.println("I can float!");
}
@Override
public void fly() {
System.out.println("I can fly!");
}
public void aMethod() {
// System.out.println(duration); // Won't compile
System.out.println(Floatable.duration); // outputs 10
System.out.println(Flyable.duration); // outputs 20
}
}

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@ -0,0 +1,12 @@
package com.baeldung.inheritance;
public class BMW extends Car {
public BMW() {
super(5, "BMW");
}
@Override
public String toString() {
return model;
}
}

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@ -0,0 +1,32 @@
package com.baeldung.inheritance;
public class Car {
private final int DEFAULT_WHEEL_COUNT = 5;
private final String DEFAULT_MODEL = "Basic";
protected int wheels;
protected String model;
public Car() {
this.wheels = DEFAULT_WHEEL_COUNT;
this.model = DEFAULT_MODEL;
}
public Car(int wheels, String model) {
this.wheels = wheels;
this.model = model;
}
public void start() {
// Check essential parts
// If okay, start.
}
public static int count = 10;
public static String msg() {
return "Car";
}
public String toString() {
return model;
}
}

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@ -0,0 +1,15 @@
package com.baeldung.inheritance;
public class Employee {
private String name;
private Car car;
public Employee(String name, Car car) {
this.name = name;
this.car = car;
}
public Car getCar() {
return car;
}
}

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@ -0,0 +1,10 @@
package com.baeldung.inheritance;
public interface Floatable {
int duration = 10;
void floatOnWater();
default void repair() {
System.out.println("Repairing Floatable object");
}
}

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@ -0,0 +1,13 @@
package com.baeldung.inheritance;
public interface Flyable {
int duration = 10;
void fly();
/*
* Commented
*/
//default void repair() {
// System.out.println("Repairing Flyable object");
//}
}

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@ -0,0 +1,18 @@
package com.baeldung.inheritance;
public class SpaceCar extends Car implements SpaceTraveller {
@Override
public void floatOnWater() {
System.out.println("SpaceCar floating!");
}
@Override
public void fly() {
System.out.println("SpaceCar flying!");
}
@Override
public void remoteControl() {
System.out.println("SpaceCar being controlled remotely!");
}
}

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@ -0,0 +1,6 @@
package com.baeldung.inheritance;
public interface SpaceTraveller extends Floatable, Flyable {
int duration = 10;
void remoteControl();
}

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@ -0,0 +1,210 @@
package com.baeldung.java.list;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
public class CustomList<E> implements List<E> {
private Object[] internal = {};
@Override
public boolean isEmpty() {
// the first cycle
// return true;
// the second cycle
// if (internal.length != 0) {
// return false;
// } else {
// return true;
// }
// refactoring
return internal.length == 0;
}
@Override
public int size() {
// the first cycle
// if (isEmpty()) {
// return 0;
// } else {
// return internal.length;
// }
// refactoring
return internal.length;
}
@SuppressWarnings("unchecked")
@Override
public E get(int index) {
// the first cycle
// return (E) internal[0];
// improvement
return (E) internal[index];
}
@Override
public boolean add(E element) {
// the first cycle
// internal = new Object[] { element };
// return true;
// the second cycle
Object[] temp = Arrays.copyOf(internal, internal.length + 1);
temp[internal.length] = element;
internal = temp;
return true;
}
@Override
public void add(int index, E element) {
throw new UnsupportedOperationException();
}
@Override
public boolean addAll(Collection<? extends E> collection) {
throw new UnsupportedOperationException();
}
@Override
public boolean addAll(int index, Collection<? extends E> collection) {
throw new UnsupportedOperationException();
}
@Override
public E remove(int index) {
throw new UnsupportedOperationException();
}
@Override
public boolean remove(Object object) {
throw new UnsupportedOperationException();
}
@Override
public boolean removeAll(Collection<?> collection) {
throw new UnsupportedOperationException();
}
@Override
public boolean retainAll(Collection<?> collection) {
throw new UnsupportedOperationException();
}
@Override
public boolean contains(Object object) {
for (Object element : internal) {
if (object.equals(element)) {
return true;
}
}
return false;
}
@Override
public boolean containsAll(Collection<?> collection) {
for (Object element : collection)
if (!contains(element)) {
return false;
}
return true;
}
@SuppressWarnings("unchecked")
@Override
public E set(int index, E element) {
E oldElement = (E) internal[index];
internal[index] = element;
return oldElement;
}
@Override
public void clear() {
internal = new Object[0];
}
@Override
public int indexOf(Object object) {
for (int i = 0; i < internal.length; i++) {
if (object.equals(internal[i])) {
return i;
}
}
return -1;
}
@Override
public int lastIndexOf(Object object) {
for (int i = internal.length - 1; i >= 0; i--) {
if (object.equals(internal[i])) {
return i;
}
}
return -1;
}
@SuppressWarnings("unchecked")
@Override
public List<E> subList(int fromIndex, int toIndex) {
Object[] temp = new Object[toIndex - fromIndex];
System.arraycopy(internal, fromIndex, temp, 0, temp.length);
return (List<E>) Arrays.asList(temp);
}
@Override
public Object[] toArray() {
return Arrays.copyOf(internal, internal.length);
}
@SuppressWarnings("unchecked")
@Override
public <T> T[] toArray(T[] array) {
if (array.length < internal.length) {
return (T[]) Arrays.copyOf(internal, internal.length, array.getClass());
}
System.arraycopy(internal, 0, array, 0, internal.length);
if (array.length > internal.length) {
array[internal.length] = null;
}
return array;
}
@Override
public Iterator<E> iterator() {
return new CustomIterator();
}
@Override
public ListIterator<E> listIterator() {
return null;
}
@Override
public ListIterator<E> listIterator(int index) {
// ignored for brevity
return null;
}
private class CustomIterator implements Iterator<E> {
int index;
@Override
public boolean hasNext() {
return index != internal.length;
}
@SuppressWarnings("unchecked")
@Override
public E next() {
E element = (E) CustomList.this.internal[index];
index++;
return element;
}
}
}

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@ -0,0 +1,26 @@
package com.baeldung.methodoverloadingoverriding.application;
import com.baeldung.methodoverloadingoverriding.model.Car;
import com.baeldung.methodoverloadingoverriding.model.Vehicle;
import com.baeldung.methodoverloadingoverriding.util.Multiplier;
public class Application {
public static void main(String[] args) {
Multiplier multiplier = new Multiplier();
System.out.println(multiplier.multiply(10, 10));
System.out.println(multiplier.multiply(10, 10, 10));
System.out.println(multiplier.multiply(10, 10.5));
System.out.println(multiplier.multiply(10.5, 10.5));
Vehicle vehicle = new Vehicle();
System.out.println(vehicle.accelerate(100));
System.out.println(vehicle.run());
System.out.println(vehicle.stop());
Vehicle car = new Car();
System.out.println(car.accelerate(80));
System.out.println(car.run());
System.out.println(car.stop());
}
}

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@ -0,0 +1,9 @@
package com.baeldung.methodoverloadingoverriding.model;
public class Car extends Vehicle {
@Override
public String accelerate(long mph) {
return "The car accelerates at : " + mph + " MPH.";
}
}

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@ -0,0 +1,16 @@
package com.baeldung.methodoverloadingoverriding.model;
public class Vehicle {
public String accelerate(long mph) {
return "The vehicle accelerates at : " + mph + " MPH.";
}
public String stop() {
return "The vehicle has stopped.";
}
public String run() {
return "The vehicle is running.";
}
}

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@ -0,0 +1,16 @@
package com.baeldung.methodoverloadingoverriding.util;
public class Multiplier {
public int multiply(int a, int b) {
return a * b;
}
public int multiply(int a, int b, int c) {
return a * b * c;
}
public double multiply(double a, double b) {
return a * b;
}
}

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@ -0,0 +1,31 @@
package com.baeldung.recursion;
public class BinaryNode {
int value;
BinaryNode left;
BinaryNode right;
public BinaryNode(int value){
this.value = value;
}
public int getValue() {
return value;
}
public void setValue(int value) {
this.value = value;
}
public BinaryNode getLeft() {
return left;
}
public void setLeft(BinaryNode left) {
this.left = left;
}
public BinaryNode getRight() {
return right;
}
public void setRight(BinaryNode right) {
this.right = right;
}
}

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@ -0,0 +1,64 @@
package com.baeldung.recursion;
public class RecursionExample {
public int sum(int n){
if (n >= 1){
return sum(n - 1) + n;
}
return n;
}
public int tailSum(int currentSum, int n){
if (n <= 1) {
return currentSum + n;
}
return tailSum(currentSum + n, n - 1);
}
public int iterativeSum(int n){
int sum = 0;
if(n < 0){
return -1;
}
for(int i=0; i<=n; i++){
sum += i;
}
return sum;
}
public int powerOf10(int n){
if (n == 0){
return 1;
}
return powerOf10(n-1)*10;
}
public int fibonacci(int n){
if (n <=1 ){
return n;
}
return fibonacci(n-1) + fibonacci(n-2);
}
public String toBinary(int n){
if (n <= 1 ){
return String.valueOf(n);
}
return toBinary(n / 2) + String.valueOf(n % 2);
}
public int calculateTreeHeight(BinaryNode root){
if (root!= null){
if (root.getLeft() != null || root.getRight() != null){
return 1 + max(calculateTreeHeight(root.left) , calculateTreeHeight(root.right));
}
}
return 0;
}
public int max(int a,int b){
return a>b ? a:b;
}
}

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@ -0,0 +1,15 @@
package com.baeldung.resourcebundle;
import java.util.Arrays;
import java.util.List;
import java.util.Locale;
import java.util.ResourceBundle;
public class ExampleControl extends ResourceBundle.Control {
@Override
public List<Locale> getCandidateLocales(String s, Locale locale) {
return Arrays.asList(new Locale("pl", "PL"));
}
}

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@ -0,0 +1,14 @@
package com.baeldung.resourcebundle;
import java.util.ListResourceBundle;
public class ExampleResource extends ListResourceBundle {
@Override
protected Object[][] getContents() {
return new Object[][] {
{ "greeting", "hello" }
};
}
}

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@ -0,0 +1,15 @@
package com.baeldung.resourcebundle;
import java.util.ListResourceBundle;
public class ExampleResource_pl extends ListResourceBundle {
@Override
protected Object[][] getContents() {
return new Object[][] {
{ "greeting", "cześć" },
{ "language", "polish" },
};
}
}

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@ -0,0 +1,17 @@
package com.baeldung.resourcebundle;
import java.math.BigDecimal;
import java.util.ListResourceBundle;
public class ExampleResource_pl_PL extends ListResourceBundle {
@Override
protected Object[][] getContents() {
return new Object[][] {
{ "currency", "polish zloty" },
{ "toUsdRate", new BigDecimal("3.401") },
{ "cities", new String[] { "Warsaw", "Cracow" } }
};
}
}

View File

@ -5,58 +5,62 @@ import java.util.stream.IntStream;
public class Palindrome {
public boolean isPalindrome(String text) {
text = text.replaceAll("\\s+", "")
.toLowerCase();
int length = text.length();
String clean = text.replaceAll("\\s+", "").toLowerCase();
int length = clean.length();
int forward = 0;
int backward = length - 1;
boolean palindrome = true;
while (backward > forward) {
char forwardChar = text.charAt(forward++);
char backwardChar = text.charAt(backward--);
char forwardChar = clean.charAt(forward++);
char backwardChar = clean.charAt(backward--);
if (forwardChar != backwardChar)
return false;
}
return palindrome;
return true;
}
public boolean isPalindromeReverseTheString(String text) {
String reverse = "";
text = text.replaceAll("\\s+", "").toLowerCase();
char[] plain = text.toCharArray();
StringBuilder reverse = new StringBuilder();
String clean = text.replaceAll("\\s+", "").toLowerCase();
char[] plain = clean.toCharArray();
for (int i = plain.length - 1; i >= 0; i--)
reverse += plain[i];
return reverse.equals(text);
reverse.append(plain[i]);
return (reverse.toString()).equals(clean);
}
public boolean isPalindromeUsingStringBuilder(String text) {
StringBuilder plain = new StringBuilder(text);
String clean = text.replaceAll("\\s+", "").toLowerCase();
StringBuilder plain = new StringBuilder(clean);
StringBuilder reverse = plain.reverse();
return reverse.equals(plain);
return (reverse.toString()).equals(clean);
}
public boolean isPalindromeUsingStringBuffer(String text) {
StringBuffer plain = new StringBuffer(text);
String clean = text.replaceAll("\\s+", "").toLowerCase();
StringBuffer plain = new StringBuffer(clean);
StringBuffer reverse = plain.reverse();
return reverse.equals(plain);
return (reverse.toString()).equals(clean);
}
public boolean isPalindromeRecursive(String text, int forward, int backward) {
public boolean isPalindromeRecursive(String text) {
String clean = text.replaceAll("\\s+", "").toLowerCase();
return recursivePalindrome(clean, 0, clean.length() - 1);
}
private boolean recursivePalindrome(String text, int forward, int backward) {
if (forward == backward)
return true;
if ((text.charAt(forward)) != (text.charAt(backward)))
return false;
if (forward < backward + 1) {
return isPalindromeRecursive(text, forward + 1, backward - 1);
return recursivePalindrome(text, forward + 1, backward - 1);
}
return true;
}
public boolean isPalindromeUsingIntStream(String text) {
String temp = text.replaceAll("\\s+", "").toLowerCase();
String temp = text.replaceAll("\\s+", "").toLowerCase();
return IntStream.range(0, temp.length() / 2)
.noneMatch(i -> temp.charAt(i) != temp.charAt(temp.length() - i - 1));
}
}

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package com.baeldung.system;
import org.apache.commons.lang3.SystemUtils;
public class DetectOS {
public String getOperatingSystem() {
String os = System.getProperty("os.name");
System.out.println("Using System Property: " + os);
return os;
}
public String getOperatingSystemSystemUtils() {
String os = SystemUtils.OS_NAME;
System.out.println("Using SystemUtils: " + os);
return os;
}
}

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# Buttons
cancelButton=cancel
continueButton continue
! Labels
helloLabel:hello

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deleteButton=delete

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backButton=cofnij
helloLabel=cze\u015b\u0107
helloLabelNoEncoding=cześć

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package com.baeldung.casting;
import org.junit.Test;
import static org.junit.Assert.*;
import java.util.ArrayList;
import java.util.List;
public class CastingTest {
@Test
public void whenPrimitiveConverted_thenValueChanged() {
double myDouble = 1.1;
int myInt = (int) myDouble;
assertNotEquals(myDouble, myInt);
}
@Test
public void whenUpcast_thenInstanceUnchanged() {
Cat cat = new Cat();
Animal animal = cat;
animal = (Animal) cat;
assertTrue(animal instanceof Cat);
}
@Test
public void whenUpcastToObject_thenInstanceUnchanged() {
Object object = new Animal();
assertTrue(object instanceof Animal);
}
@Test
public void whenUpcastToInterface_thenInstanceUnchanged() {
Mew mew = new Cat();
assertTrue(mew instanceof Cat);
}
@Test
public void whenUpcastToAnimal_thenOverridenMethodsCalled() {
List<Animal> animals = new ArrayList<>();
animals.add(new Cat());
animals.add(new Dog());
new AnimalFeeder().feed(animals);
}
@Test
public void whenDowncastToCat_thenMeowIsCalled() {
Animal animal = new Cat();
((Cat) animal).meow();
}
@Test(expected = ClassCastException.class)
public void whenDownCastWithoutCheck_thenExceptionThrown() {
List<Animal> animals = new ArrayList<>();
animals.add(new Cat());
animals.add(new Dog());
new AnimalFeeder().uncheckedFeed(animals);
}
}

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package com.baeldung.classloader;
import org.junit.Test;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
public class CustomClassLoaderTest {
@Test
public void customLoader() throws ClassNotFoundException, IllegalAccessException, InstantiationException, NoSuchMethodException, InvocationTargetException {
CustomClassLoader customClassLoader = new CustomClassLoader();
Class<?> c = customClassLoader.getClass(PrintClassLoader.class.getName());
Object ob = c.newInstance();
Method md = c.getMethod("printClassLoaders");
md.invoke(ob);
}
}

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package com.baeldung.classloader;
import org.junit.Test;
import static org.junit.Assert.*;
public class PrintClassLoaderTest {
@Test(expected = ClassNotFoundException.class)
public void givenAppClassLoader_whenParentClassLoader_thenClassNotFoundException() throws Exception {
PrintClassLoader sampleClassLoader = (PrintClassLoader) Class.forName(PrintClassLoader.class.getName()).newInstance();
sampleClassLoader.printClassLoaders();
Class.forName(PrintClassLoader.class.getName(), true, PrintClassLoader.class.getClassLoader().getParent());
}
}

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package com.baeldung.decimalformat;
import static org.assertj.core.api.Assertions.assertThat;
import java.math.BigDecimal;
import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.text.NumberFormat;
import java.text.ParseException;
import java.util.Locale;
import org.junit.Test;
public class DecimalFormatExamplesTest {
double d = 1234567.89;
@Test
public void givenSimpleDecimal_WhenFormatting_ThenCorrectOutput() {
assertThat(new DecimalFormat("#.##", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
.isEqualTo("1234567.89");
assertThat(new DecimalFormat("0.00", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
.isEqualTo("1234567.89");
assertThat(new DecimalFormat("#########.###", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
.isEqualTo("1234567.89");
assertThat(new DecimalFormat("000000000.000", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
.isEqualTo("001234567.890");
}
@Test
public void givenSmallerDecimalPattern_WhenFormatting_ThenRounding() {
assertThat(new DecimalFormat("#.#", new DecimalFormatSymbols(Locale.ENGLISH)).format(d)).isEqualTo("1234567.9");
assertThat(new DecimalFormat("#", new DecimalFormatSymbols(Locale.ENGLISH)).format(d)).isEqualTo("1234568");
}
@Test
public void givenGroupingSeparator_WhenFormatting_ThenGroupedOutput() {
assertThat(new DecimalFormat("#,###.#", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
.isEqualTo("1,234,567.9");
assertThat(new DecimalFormat("#,###", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
.isEqualTo("1,234,568");
}
@Test
public void givenMixedPattern_WhenFormatting_ThenCorrectOutput() {
assertThat(new DecimalFormat("The # number", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
.isEqualTo("The 1234568 number");
assertThat(new DecimalFormat("The '#' # number", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
.isEqualTo("The # 1234568 number");
}
@Test
public void givenLocales_WhenFormatting_ThenCorrectOutput() {
assertThat(new DecimalFormat("#,###.##", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
.isEqualTo("1,234,567.89");
assertThat(new DecimalFormat("#,###.##", new DecimalFormatSymbols(Locale.ITALIAN)).format(d))
.isEqualTo("1.234.567,89");
assertThat(new DecimalFormat("#,###.##", DecimalFormatSymbols.getInstance(new Locale("it", "IT"))).format(d))
.isEqualTo("1.234.567,89");
}
@Test
public void givenE_WhenFormatting_ThenScientificNotation() {
assertThat(new DecimalFormat("00.#######E0", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
.isEqualTo("12.3456789E5");
assertThat(new DecimalFormat("000.000000E0", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
.isEqualTo("123.456789E4");
assertThat(new DecimalFormat("##0.######E0", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
.isEqualTo("1.23456789E6");
assertThat(new DecimalFormat("###.000000E0", new DecimalFormatSymbols(Locale.ENGLISH)).format(d))
.isEqualTo("1.23456789E6");
}
@Test
public void givenString_WhenParsing_ThenCorrectOutput() throws ParseException {
assertThat(new DecimalFormat("", new DecimalFormatSymbols(Locale.ENGLISH)).parse("1234567.89"))
.isEqualTo(1234567.89);
assertThat(new DecimalFormat("", new DecimalFormatSymbols(Locale.ITALIAN)).parse("1.234.567,89"))
.isEqualTo(1234567.89);
}
@Test
public void givenStringAndBigDecimalFlag_WhenParsing_ThenCorrectOutput() throws ParseException {
NumberFormat nf = new DecimalFormat("", new DecimalFormatSymbols(Locale.ENGLISH));
((DecimalFormat) nf).setParseBigDecimal(true);
assertThat(nf.parse("1234567.89")).isEqualTo(BigDecimal.valueOf(1234567.89));
}
}

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package com.baeldung.deepcopy;
import static org.assertj.core.api.Assertions.assertThat;
import java.io.IOException;
import org.apache.commons.lang.SerializationUtils;
import org.junit.Ignore;
import org.junit.Test;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.gson.Gson;
public class DeepCopyUnitTest {
@Test
public void whenCreatingDeepCopyWithCopyConstructor_thenObjectsShouldNotBeSame() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
User deepCopy = new User(pm);
assertThat(deepCopy).isNotSameAs(pm);
}
@Test
public void whenModifyingOriginalObject_thenConstructorCopyShouldNotChange() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
User deepCopy = new User(pm);
address.setCountry("Great Britain");
assertThat(deepCopy.getAddress().getCountry()).isNotEqualTo(pm.getAddress().getCountry());
}
@Test
public void whenModifyingOriginalObject_thenCloneCopyShouldNotChange() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
User deepCopy = (User) pm.clone();
address.setCountry("Great Britain");
assertThat(deepCopy.getAddress().getCountry()).isNotEqualTo(pm.getAddress().getCountry());
}
@Test
public void whenModifyingOriginalObject_thenCommonsCloneShouldNotChange() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
User deepCopy = (User) SerializationUtils.clone(pm);
address.setCountry("Great Britain");
assertThat(deepCopy.getAddress().getCountry()).isNotEqualTo(pm.getAddress().getCountry());
}
@Test
public void whenModifyingOriginalObject_thenGsonCloneShouldNotChange() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
Gson gson = new Gson();
User deepCopy = gson.fromJson(gson.toJson(pm), User.class);
address.setCountry("Great Britain");
assertThat(deepCopy.getAddress().getCountry()).isNotEqualTo(pm.getAddress().getCountry());
}
@Test
public void whenModifyingOriginalObject_thenJacksonCopyShouldNotChange() throws IOException {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
ObjectMapper objectMapper = new ObjectMapper();
User deepCopy = objectMapper.readValue(objectMapper.writeValueAsString(pm), User.class);
address.setCountry("Great Britain");
assertThat(deepCopy.getAddress().getCountry()).isNotEqualTo(pm.getAddress().getCountry());
}
@Test
@Ignore
public void whenMakingCopies_thenShowHowLongEachMethodTakes() throws CloneNotSupportedException, IOException {
int times = 1000000;
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
long start = System.currentTimeMillis();
for (int i = 0; i < times; i++) {
User primeMinisterClone = (User) SerializationUtils.clone(pm);
}
long end = System.currentTimeMillis();
System.out.println("Cloning with Apache Commons Lang took " + (end - start) + " milliseconds.");
start = System.currentTimeMillis();
Gson gson = new Gson();
for (int i = 0; i < times; i++) {
User primeMinisterClone = gson.fromJson(gson.toJson(pm), User.class);
}
end = System.currentTimeMillis();
System.out.println("Cloning with Gson took " + (end - start) + " milliseconds.");
start = System.currentTimeMillis();
for (int i = 0; i < times; i++) {
User primeMinisterClone = new User(pm);
}
end = System.currentTimeMillis();
System.out.println("Cloning with the copy constructor took " + (end - start) + " milliseconds.");
start = System.currentTimeMillis();
for (int i = 0; i < times; i++) {
User primeMinisterClone = (User) pm.clone();
}
end = System.currentTimeMillis();
System.out.println("Cloning with Cloneable interface took " + (end - start) + " milliseconds.");
start = System.currentTimeMillis();
ObjectMapper objectMapper = new ObjectMapper();
for (int i = 0; i < times; i++) {
User primeMinisterClone = objectMapper.readValue(objectMapper.writeValueAsString(pm), User.class);
}
end = System.currentTimeMillis();
System.out.println("Cloning with Jackson took " + (end - start) + " milliseconds.");
}
}

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package com.baeldung.deepcopy;
import static org.assertj.core.api.Assertions.assertThat;
import org.junit.Test;
public class ShallowCopyUnitTest {
@Test
public void whenShallowCopying_thenObjectsShouldNotBeSame() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
User shallowCopy = new User(pm.getFirstName(), pm.getLastName(), pm.getAddress());
assertThat(shallowCopy)
.isNotSameAs(pm);
}
@Test
public void whenModifyingOriginalObject_thenCopyShouldChange() {
Address address = new Address("Downing St 10", "London", "England");
User pm = new User("Prime", "Minister", address);
User shallowCopy = new User(pm.getFirstName(), pm.getLastName(), pm.getAddress());
address.setCountry("Great Britain");
assertThat(shallowCopy.getAddress().getCountry())
.isEqualTo(pm.getAddress().getCountry());
}
}

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package com.baeldung.designpatterns.chainofresponsibility;
import org.junit.Test;
import static org.junit.Assert.assertTrue;
public class ChainOfResponsibilityTest {
private static AuthenticationProcessor getChainOfAuthProcessor() {
AuthenticationProcessor oAuthProcessor = new OAuthAuthenticationProcessor(null);
AuthenticationProcessor unamePasswordProcessor = new UsernamePasswordAuthenticationProcessor(oAuthProcessor);
return unamePasswordProcessor;
}
@Test
public void givenOAuthProvider_whenCheckingAuthorized_thenSuccess() {
AuthenticationProcessor authProcessorChain = getChainOfAuthProcessor();
boolean isAuthorized = authProcessorChain.isAuthorized(new OAuthTokenProvider());
assertTrue(isAuthorized);
}
@Test
public void givenUsernamePasswordProvider_whenCheckingAuthorized_thenSuccess() {
AuthenticationProcessor authProcessorChain = getChainOfAuthProcessor();
boolean isAuthorized = authProcessorChain.isAuthorized(new UsernamePasswordProvider());
assertTrue(isAuthorized);
}
@Test
public void givenSamlAuthProvider_whenCheckingAuthorized_thenFailure() {
AuthenticationProcessor authProcessorChain = getChainOfAuthProcessor();
boolean isAuthorized = authProcessorChain.isAuthorized(new SamlAuthenticationProvider());
assertTrue(!isAuthorized);
}
}

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package com.baeldung.designpatterns.flyweight;
import java.awt.Color;
import org.junit.Assert;
import org.junit.Test;
/**
* Unit test for {@link VehicleFactory}.
*
* @author Donato Rimenti
*/
public class FlyweightUnitTest {
/**
* Checks that when the {@link VehicleFactory} is asked to provide two
* vehicles of different colors, the objects returned are different.
*/
@Test
public void givenDifferentFlyweightObjects_whenEquals_thenFalse() {
Vehicle blackVehicle = VehicleFactory.createVehicle(Color.BLACK);
Vehicle blueVehicle = VehicleFactory.createVehicle(Color.BLUE);
Assert.assertNotNull("Object returned by the factory is null!", blackVehicle);
Assert.assertNotNull("Object returned by the factory is null!", blueVehicle);
Assert.assertNotEquals("Objects returned by the factory are equals!", blackVehicle, blueVehicle);
}
/**
* Checks that when the {@link VehicleFactory} is asked to provide two
* vehicles of the same colors, the same object is returned twice.
*/
@Test
public void givenSameFlyweightObjects_whenEquals_thenTrue() {
Vehicle blackVehicle = VehicleFactory.createVehicle(Color.BLACK);
Vehicle anotherBlackVehicle = VehicleFactory.createVehicle(Color.BLACK);
Assert.assertNotNull("Object returned by the factory is null!", blackVehicle);
Assert.assertNotNull("Object returned by the factory is null!", anotherBlackVehicle);
Assert.assertEquals("Objects returned by the factory are not equals!", blackVehicle, anotherBlackVehicle);
}
}

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package com.baeldung.inheritance;
import com.baeldung.inheritance.*;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
public class AppTest extends TestCase {
public AppTest(String testName) {
super( testName );
}
public static Test suite() {
return new TestSuite(AppTest.class);
}
@SuppressWarnings("static-access")
public void testStaticMethodUsingBaseClassVariable() {
Car first = new ArmoredCar();
assertEquals("Car", first.msg());
}
@SuppressWarnings("static-access")
public void testStaticMethodUsingDerivedClassVariable() {
ArmoredCar second = new ArmoredCar();
assertEquals("ArmoredCar", second.msg());
}
public void testAssignArmoredCarToCar() {
Employee e1 = new Employee("Shreya", new ArmoredCar());
assertNotNull(e1.getCar());
}
public void testAssignSpaceCarToCar() {
Employee e2 = new Employee("Paul", new SpaceCar());
assertNotNull(e2.getCar());
}
public void testBMWToCar() {
Employee e3 = new Employee("Pavni", new BMW());
assertNotNull(e3.getCar());
}
}

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package com.baeldung.java.list;
import static org.junit.Assert.assertArrayEquals;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import org.junit.Test;
public class CustomListUnitTest {
@Test
public void givenEmptyList_whenIsEmpty_thenTrueIsReturned() {
List<Object> list = new CustomList<>();
assertTrue(list.isEmpty());
}
@Test
public void givenNonEmptyList_whenIsEmpty_thenFalseIsReturned() {
List<Object> list = new CustomList<>();
list.add(null);
assertFalse(list.isEmpty());
}
@Test
public void givenListWithAnElement_whenSize_thenOneIsReturned() {
List<Object> list = new CustomList<>();
list.add(null);
assertEquals(1, list.size());
}
@Test
public void givenListWithAnElement_whenGet_thenThatElementIsReturned() {
List<Object> list = new CustomList<>();
list.add("baeldung");
Object element = list.get(0);
assertEquals("baeldung", element);
}
@Test
public void givenEmptyList_whenElementIsAdded_thenGetReturnsThatElement() {
List<Object> list = new CustomList<>();
boolean succeeded = list.add(null);
assertTrue(succeeded);
}
@Test
public void givenListWithAnElement_whenAnotherIsAdded_thenGetReturnsBoth() {
List<Object> list = new CustomList<>();
list.add("baeldung");
list.add(".com");
Object element1 = list.get(0);
Object element2 = list.get(1);
assertEquals("baeldung", element1);
assertEquals(".com", element2);
}
@Test(expected = UnsupportedOperationException.class)
public void whenAddToSpecifiedIndex_thenExceptionIsThrown() {
new CustomList<>().add(0, null);
}
@Test(expected = UnsupportedOperationException.class)
public void whenAddAllToTheEnd_thenExceptionIsThrown() {
Collection<Object> collection = new ArrayList<>();
List<Object> list = new CustomList<>();
list.addAll(collection);
}
@Test(expected = UnsupportedOperationException.class)
public void whenAddAllToSpecifiedIndex_thenExceptionIsThrown() {
Collection<Object> collection = new ArrayList<>();
List<Object> list = new CustomList<>();
list.addAll(0, collection);
}
@Test(expected = UnsupportedOperationException.class)
public void whenRemoveAtSpecifiedIndex_thenExceptionIsThrown() {
List<Object> list = new CustomList<>();
list.add("baeldung");
list.remove(0);
}
@Test(expected = UnsupportedOperationException.class)
public void whenRemoveSpecifiedElement_thenExceptionIsThrown() {
List<Object> list = new CustomList<>();
list.add("baeldung");
list.remove("baeldung");
}
@Test(expected = UnsupportedOperationException.class)
public void whenRemoveAll_thenExceptionIsThrown() {
Collection<Object> collection = new ArrayList<>();
collection.add("baeldung");
List<Object> list = new CustomList<>();
list.removeAll(collection);
}
@Test(expected = UnsupportedOperationException.class)
public void whenRetainAll_thenExceptionIsThrown() {
Collection<Object> collection = new ArrayList<>();
collection.add("baeldung");
List<Object> list = new CustomList<>();
list.add("baeldung");
list.retainAll(collection);
}
@Test
public void givenEmptyList_whenContains_thenFalseIsReturned() {
List<Object> list = new CustomList<>();
assertFalse(list.contains(null));
}
@Test
public void givenListWithAnElement_whenContains_thenTrueIsReturned() {
List<Object> list = new CustomList<>();
list.add("baeldung");
assertTrue(list.contains("baeldung"));
}
@Test
public void givenListWithAnElement_whenContainsAll_thenTrueIsReturned() {
Collection<Object> collection = new ArrayList<>();
collection.add("baeldung");
List<Object> list = new CustomList<>();
list.add("baeldung");
assertTrue(list.containsAll(collection));
}
@Test
public void givenList_whenContainsAll_thenEitherTrueOrFalseIsReturned() {
Collection<Object> collection1 = new ArrayList<>();
collection1.add("baeldung");
collection1.add(".com");
Collection<Object> collection2 = new ArrayList<>();
collection2.add("baeldung");
List<Object> list = new CustomList<>();
list.add("baeldung");
assertFalse(list.containsAll(collection1));
assertTrue(list.containsAll(collection2));
}
@Test
public void givenList_whenSet_thenOldElementIsReturned() {
List<Object> list = new CustomList<>();
list.add("baeldung");
Object element = list.set(0, null);
assertEquals("baeldung", element);
assertNull(list.get(0));
}
@Test
public void givenList_whenClear_thenAllElementsAreRemoved() {
List<Object> list = new CustomList<>();
list.add("baeldung");
list.clear();
assertTrue(list.isEmpty());
}
@Test
public void givenList_whenIndexOf_thenIndexZeroIsReturned() {
List<Object> list = new CustomList<>();
list.add("baeldung");
assertEquals(0, list.indexOf("baeldung"));
}
@Test
public void givenList_whenIndexOf_thenPositiveIndexOrMinusOneIsReturned() {
List<Object> list = new CustomList<>();
list.add("baeldung");
list.add(".com");
list.add(".com");
assertEquals(1, list.indexOf(".com"));
assertEquals(-1, list.indexOf("com"));
}
@Test
public void whenLastIndexOf_thenIndexZeroIsReturned() {
List<Object> list = new CustomList<>();
list.add("baeldung");
assertEquals(0, list.lastIndexOf("baeldung"));
}
@Test
public void whenLastIndexOf_thenPositiveIndexOrMinusOneIsReturned() {
List<Object> list = new CustomList<>();
list.add("baeldung");
list.add("baeldung");
list.add(".com");
assertEquals(1, list.lastIndexOf("baeldung"));
assertEquals(-1, list.indexOf("com"));
}
@Test
public void whenSubListZeroToOne_thenListContainingFirstElementIsReturned() {
List<Object> list = new CustomList<>();
list.add("baeldung");
List<Object> subList = list.subList(0, 1);
assertEquals("baeldung", subList.get(0));
}
@Test
public void whenSubListOneToTwo_thenListContainingSecondElementIsReturned() {
List<Object> list = new CustomList<>();
list.add("baeldung");
list.add(".");
list.add("com");
List<Object> subList = list.subList(1, 2);
assertEquals(1, subList.size());
assertEquals(".", subList.get(0));
}
@Test
public void givenListWithElements_whenToArray_thenArrayContainsThose() {
List<Object> list = new CustomList<>();
list.add("baeldung");
list.add(".com");
Object[] array = list.toArray();
assertArrayEquals(new Object[] { "baeldung", ".com" }, array);
}
@Test
public void givenListWithAnElement_whenToArray_thenInputArrayIsReturned() {
List<Object> list = new CustomList<>();
list.add("baeldung");
String[] input = new String[1];
String[] output = list.toArray(input);
assertArrayEquals(new String[] { "baeldung" }, input);
}
@Test
public void whenToArrayIsCalledWithEmptyInputArray_thenNewArrayIsReturned() {
List<Object> list = new CustomList<>();
list.add("baeldung");
String[] input = {};
String[] output = list.toArray(input);
assertArrayEquals(new String[] { "baeldung" }, output);
}
@Test
public void whenToArrayIsCalledWithLargerInput_thenOutputHasTrailingNull() {
List<Object> list = new CustomList<>();
list.add("baeldung");
String[] input = new String[2];
String[] output = list.toArray(input);
assertArrayEquals(new String[] { "baeldung", null }, output);
}
@Test
public void givenListWithOneElement_whenIterator_thenThisElementIsNext() {
List<Object> list = new CustomList<>();
list.add("baeldung");
Iterator<Object> iterator = list.iterator();
assertTrue(iterator.hasNext());
assertEquals("baeldung", iterator.next());
}
@Test
public void whenIteratorHasNextIsCalledTwice_thenTheSecondReturnsFalse() {
List<Object> list = new CustomList<>();
list.add("baeldung");
Iterator<Object> iterator = list.iterator();
iterator.next();
assertFalse(iterator.hasNext());
}
}

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package com.baeldung.methodoverloadingoverriding.test;
import com.baeldung.methodoverloadingoverriding.util.Multiplier;
import org.junit.BeforeClass;
import org.junit.Test;
import static org.assertj.core.api.Assertions.*;
public class MethodOverloadingUnitTest {
private static Multiplier multiplier;
@BeforeClass
public static void setUpMultiplierInstance() {
multiplier = new Multiplier();
}
@Test
public void givenMultiplierInstance_whenCalledMultiplyWithTwoIntegers_thenOneAssertion() {
assertThat(multiplier.multiply(10, 10)).isEqualTo(100);
}
@Test
public void givenMultiplierInstance_whenCalledMultiplyWithTreeIntegers_thenOneAssertion() {
assertThat(multiplier.multiply(10, 10, 10)).isEqualTo(1000);
}
@Test
public void givenMultiplierInstance_whenCalledMultiplyWithIntDouble_thenOneAssertion() {
assertThat(multiplier.multiply(10, 10.5)).isEqualTo(105.0);
}
@Test
public void givenMultiplierInstance_whenCalledMultiplyWithDoubleDouble_thenOneAssertion() {
assertThat(multiplier.multiply(10.5, 10.5)).isEqualTo(110.25);
}
@Test
public void givenMultiplierInstance_whenCalledMultiplyWithIntIntAndMatching_thenNoTypePromotion() {
assertThat(multiplier.multiply(10, 10)).isEqualTo(100);
}
}

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package com.baeldung.methodoverloadingoverriding.test;
import com.baeldung.methodoverloadingoverriding.model.Car;
import com.baeldung.methodoverloadingoverriding.model.Vehicle;
import org.junit.BeforeClass;
import org.junit.Test;
import static org.assertj.core.api.Assertions.*;
public class MethodOverridingUnitTest {
private static Vehicle vehicle;
private static Car car;
@BeforeClass
public static void setUpVehicleInstance() {
vehicle = new Vehicle();
}
@BeforeClass
public static void setUpCarInstance() {
car = new Car();
}
@Test
public void givenVehicleInstance_whenCalledAccelerate_thenOneAssertion() {
assertThat(vehicle.accelerate(100)).isEqualTo("The vehicle accelerates at : 100 MPH.");
}
@Test
public void givenVehicleInstance_whenCalledRun_thenOneAssertion() {
assertThat(vehicle.run()).isEqualTo("The vehicle is running.");
}
@Test
public void givenVehicleInstance_whenCalledStop_thenOneAssertion() {
assertThat(vehicle.stop()).isEqualTo("The vehicle has stopped.");
}
@Test
public void givenCarInstance_whenCalledAccelerate_thenOneAssertion() {
assertThat(car.accelerate(80)).isEqualTo("The car accelerates at : 80 MPH.");
}
@Test
public void givenCarInstance_whenCalledRun_thenOneAssertion() {
assertThat(car.run()).isEqualTo("The vehicle is running.");
}
@Test
public void givenCarInstance_whenCalledStop_thenOneAssertion() {
assertThat(car.stop()).isEqualTo("The vehicle has stopped.");
}
@Test
public void givenVehicleCarInstances_whenCalledAccelerateWithSameArgument_thenNotEqual() {
assertThat(vehicle.accelerate(100)).isNotEqualTo(car.accelerate(100));
}
@Test
public void givenVehicleCarInstances_whenCalledRun_thenEqual() {
assertThat(vehicle.run()).isEqualTo(car.run());
}
@Test
public void givenVehicleCarInstances_whenCalledStop_thenEqual() {
assertThat(vehicle.stop()).isEqualTo(car.stop());
}
}

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package com.baeldung.recursion;
import org.junit.Assert;
import org.junit.Test;
public class RecursionExampleTest {
RecursionExample recursion = new RecursionExample();
@Test
public void testPowerOf10() {
int p0 = recursion.powerOf10(0);
int p1 = recursion.powerOf10(1);
int p4 = recursion.powerOf10(4);
Assert.assertEquals(1, p0);
Assert.assertEquals(10, p1);
Assert.assertEquals(10000, p4);
}
@Test
public void testFibonacci() {
int n0 = recursion.fibonacci(0);
int n1 = recursion.fibonacci(1);
int n7 = recursion.fibonacci(7);
Assert.assertEquals(0, n0);
Assert.assertEquals(1, n1);
Assert.assertEquals(13, n7);
}
@Test
public void testToBinary() {
String b0 = recursion.toBinary(0);
String b1 = recursion.toBinary(1);
String b10 = recursion.toBinary(10);
Assert.assertEquals("0", b0);
Assert.assertEquals("1", b1);
Assert.assertEquals("1010", b10);
}
@Test
public void testCalculateTreeHeight() {
BinaryNode root = new BinaryNode(1);
root.setLeft(new BinaryNode(1));
root.setRight(new BinaryNode(1));
root.getLeft().setLeft(new BinaryNode(1));
root.getLeft().getLeft().setRight(new BinaryNode(1));
root.getLeft().getLeft().getRight().setLeft(new BinaryNode(1));
root.getRight().setLeft(new BinaryNode(1));
root.getRight().getLeft().setRight(new BinaryNode(1));
int height = recursion.calculateTreeHeight(root);
Assert.assertEquals(4, height);
}
}

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