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Game collision detection with rectangles

I have started with my first game but cannot figure out how the collision detection should work. The goal is that the player should not be able to go into the wall.
I have following classes Player(), Wall(), Levels() and Game()
Player class is loading the player and handling movement and collisions for the player.
Wall is creating walls, I have one Arraylist in this class which is creating an rectangle for each wall that is created.
Levels class is loading creating and loading all the levels.
Game class is handling the whole game loop and more.
I have tried to compare x and y positions with player and wall, right now I am trying to use the .intersect class which has not been succesfull yet.
Part of Player Class:
public void collision() {
Rectangle r3 = getOffsetBounds();
for (int i = 0; i < Wall.wallList.size(); i++) {
Rectangle w1 = Wall.wallList.get(i);
if (r3.intersects(w1)) {
}}}
public int moveUp(int velY) {
collision();
y -= velY;
return y;
}
public int moveDown(int velY) {
collision();
y += velY;
return y;
}
public int moveLeft(int velX) {
collision();
x -= velX;
return x;
}
public int moveRight(int velX) {
collision();
x += velX;
return x;
}
public Rectangle getOffsetBounds() {
return new Rectangle(x + velX, y + velY, width, height);
}
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
public int getVelX() {
return velX;
}
public void setVelX(int velX) {
this.velX = velX;
}
public int getVelY() {
return velY;
}
public void setVelY(int velY) {
this.velY = velY;
}}
Part of Wall Class:
static ArrayList<Rectangle> wallList = new ArrayList<Rectangle>();
public int getX() {
return x;
}
public void setX(int x) {
this.x = x;
}
public int getY() {
return y;
}
public void setY(int y) {
this.y = y;
}
public void setVisisble(Boolean visible) {
this.visible = visible;
}
public Rectangle getBounds() {
return new Rectangle(x,y,width,height);
}
public Rectangle setBounds(int x,int y,int width,int height) {
this.x = x;
this.y = y;
this.width = width;
this.height = height;
return new Rectangle(x,y,width,height);
}}
Part of Levels class where the wall list is setting
if(level1[i][j]==1) {
w = new Wall(j*25, i*25, width, height);
w.paint(g);
Wall.wallList.add(w.setBounds(j*25+10, i*25+10, width, height));
}
Part of Game class where keybindings are
public void KeyBindings() {
keyManager.addKeyBinding(lvl, KeyEvent.VK_UP, "moveUp", (evt) -> {
lvl.player.moveUp(5);
});
keyManager.addKeyBinding(lvl, KeyEvent.VK_DOWN, "moveDown", (evt) -> {
lvl.player.moveDown(5);
});
keyManager.addKeyBinding(lvl, KeyEvent.VK_LEFT, "moveLeft", (evt) -> {
lvl.player.moveLeft(5);
});
keyManager.addKeyBinding(lvl, KeyEvent.VK_RIGHT, "moveRight", (evt) -> {
lvl.player.moveRight(5);
});
}

This is how I always handle any collisions
if (((x1<x2 && x1+w1>x2) || (x2<x1 && x2+w2>x1)) &&
((y1<y2 && y1+h1>y2) || (y2<y1 && y2+h2>y1)))

How to spawn collectibles at random positions in Java

I making a game in Android Studio with Java. I am having an issue where my collectible keeps re-spawning in the same position after the player has collected it. I would like for it to re-spawn at random positions on the screen. How can I do this?
The collectible is a fuel can.
Here is the fuel can collectible class
Fuel.java
public class Fuel extends GameObject {
public Fuel(Bitmap res, int w, int h, int numFrames) {
x = GamePanel.WIDTH + 5000;
y = GamePanel.HEIGHT / 2;
dy =(random.nextInt()*(GamePanel.HEIGHT - (maxBorderHeight* 2)+maxBorderHeight));
dx = +GamePanel.MOVESPEED;
height = h;
width = w;
Bitmap[] image = new Bitmap[numFrames];
spritesheet = res;
for (int i = 0; i < image.length; i++)
{
image[i] = Bitmap.createBitmap(spritesheet, 0, i*height, width, height);
}
animation.setFrames(image);
animation.setDelay(100-dx);
animation.update();
}
public void update()
{
if (x < 0) {
reset();
}
x += dx;
dx = dx- 1;
if (dx <= -15) {
dx = -15;
}
animation.update();
}
public void draw(Canvas canvas)
{
try {
canvas.drawBitmap(animation.getImage(),x,y,null);
}catch (Exception e){}
}
public void reset(){
x = GamePanel.WIDTH + 5000;
y = GamePanel.HEIGHT/2 ;
dy = (random.nextInt()*(GamePanel.HEIGHT - (maxBorderHeight* 2)+maxBorderHeight));
dx = +GamePanel.MOVESPEED;
}
public void fuelCollected(){
reset();
}
}
GamePanel.java
public class GamePanel extends SurfaceView implements SurfaceHolder.Callback
{
private Fuel fuel;
#Override
public void surfaceCreated(SurfaceHolder holder){
fuel = new Fuel(BitmapFactory.decodeResource(getResources(), R.drawable.fuel),40,40,1);
}
public void update()
{
fuel.update();
if(collectFuel(player,fuel)){
distance +=100;
}
public boolean collectFuel(GameObject player, GameObject fuel){
if(Rect.intersects(player.getRectangle(),fuel.getRectangle()))
{
fuelCollected();
return true;
}
return false;
}
public void fuelCollected(){fuel.fuelCollected();}
}
#Override
public void draw(Canvas canvas){
// draw fuel can
fuel.draw(canvas);
}
}

Change Fuel reset() method to something like this:
public void reset() {
x = random.nextInt(GamePanel.WIDTH);
y = random.nextInt(GamePanel.HEIGHT);
dy = (random.nextInt()*(GamePanel.HEIGHT - (maxBorderHeight* 2)+maxBorderHeight));
dx = +GamePanel.MOVESPEED;
}
Assuming that x, y are integer variables x will be a random integer between 0 and GamePanel.WIDTH and y a random integer between 0 and GamePanel.HEIGHT.
Why do you add 5000 to the GamePanel.WIDTH ?

Java Multithreading Mouse Click

After making changes based on a previous post I have taken the following code a few steps further by introducing single/double click recognition. Why are the balls being created in the top left corner and not where the mouse is clicked?
BouncingBalls.java
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
public class BouncingBalls extends JPanel implements MouseListener {
protected List<RandomBall> randomBalls = new ArrayList<RandomBall>(20);
protected List<VerticalBall> verticalBalls = new ArrayList<VerticalBall>(20);
private Container container;
private DrawCanvas canvas;
private Boolean doubleClick = false;
private final Integer waitTime = (Integer) Toolkit.getDefaultToolkit()
.getDesktopProperty("awt.multiClickInterval");
private static int canvasWidth = 500;
private static int canvasHeight = 500;
public static final int UPDATE_RATE = 30;
int count = 0;
public static int random(int maxRange) {
return (int) Math.round((Math.random() * maxRange));
}
public BouncingBalls(int width, int height) {
canvasWidth = width;
canvasHeight = height;
container = new Container();
canvas = new DrawCanvas();
this.setLayout(new BorderLayout());
this.add(canvas, BorderLayout.CENTER);
this.addMouseListener(this);
start();
}
public void start() {
Thread t = new Thread() {
public void run() {
while (true) {
update();
repaint();
try {
Thread.sleep(1000 / UPDATE_RATE);
} catch (InterruptedException e) {
}
}
}
};
t.start();
}
public void update() {
for (RandomBall ball : randomBalls) {
ball.ballBounce(container);
}
for (VerticalBall ball : verticalBalls) {
ball.verticalBounce(container);
}
}
class DrawCanvas extends JPanel {
public void paintComponent(Graphics g) {
super.paintComponent(g);
container.draw(g);
for (RandomBall ball : randomBalls) {
ball.draw(g);
}
for (VerticalBall ball : verticalBalls) {
ball.draw(g);
}
}
public Dimension getPreferredSize() {
return (new Dimension(canvasWidth, canvasHeight));
}
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
JFrame f = new JFrame("Stack Answer 2");
f.setDefaultCloseOperation(f.EXIT_ON_CLOSE);
f.setContentPane(new BouncingBalls(canvasHeight, canvasWidth));
f.pack();
f.setVisible(true);
}
});
}
#Override
public void mouseClicked(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mousePressed(MouseEvent e) {
if (e.getClickCount() >= 2) {
doubleClick = true;
verticalBalls.add(new VerticalBall(getX(), getY(), canvasWidth, canvasHeight));
System.out.println("double click");
} else {
Timer timer = new Timer(waitTime, new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (doubleClick) {
/* we are the first click of a double click */
doubleClick = false;
} else {
count++;
randomBalls.add(new RandomBall(getX(), getY(), canvasWidth, canvasHeight));
/* the second click never happened */
System.out.println("single click");
}
}
});
timer.setRepeats(false);
timer.start();
}
}
#Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
}
RandomBall.java
import java.awt.Color;
import java.awt.Graphics;
public class RandomBall {
public static int random(int maxRange) {
return (int) Math.round((Math.random() * maxRange));
}
private int x;
private int y;
private int canvasWidth = 500;
private int canvasHeight = 500;
private boolean leftRight;
private boolean upDown;
private int deltaX;
private int deltaY;
private int radius = 20;
private int red = random(255);
private int green = random(255);
private int blue = random(255);
RandomBall(int x, int y, int width, int height) {
this(x, y, width, height, false, false);
}
RandomBall(int x, int y, int width, int height, boolean leftRight, boolean upDown) {
this.x = x;
this.y = y;
this.canvasWidth = width;
this.canvasHeight = height;
this.leftRight = leftRight;
this.upDown = upDown;
updateDelta();
}
public void draw(Graphics g) {
g.setColor(new Color(red, green, blue));
g.fillOval((int) (x - radius), (int) (y - radius), (int) (2 * radius),
(int) (2 * radius));
}
private void updateDelta() {
final int minimumMovement = 5;
final int maxExtra = 10;
deltaY = minimumMovement + (int) (Math.random() * maxExtra);
deltaX = minimumMovement + (int) (Math.random() * maxExtra);
}
public void ballBounce(Container container) {
// controls horizontal ball motion
if (leftRight) {
x += deltaX;
if (x >= getWidth()) {
leftRight = false;
updateDelta();
}
} else {
x += -deltaX;
if (x <= 0) {
leftRight = true;
updateDelta();
}
}
// controls vertical ball motion
if (upDown) {
y += deltaY;
if (y >= getHeight()) {
upDown = false;
updateDelta();
}
} else {
y += -deltaY;
if (y <= 0) {
upDown = true;
updateDelta();
}
}
}
public void verticalBounce(Container container) {
// controls vertical ball motion
if (upDown) {
y += deltaY;
if (y >= getHeight()) {
upDown = false;
updateDelta();
}
} else {
y += -deltaY;
if (y <= 0) {
upDown = true;
updateDelta();
}
}
}
public int getX() {
return x;
}
public int getY() {
return y;
}
public int getWidth() {
return canvasWidth;
}
public int getHeight() {
return canvasHeight;
}
}
VerticalBall.java
import java.awt.Color;
import java.awt.Graphics;
public class VerticalBall {
public static int random(int maxRange) {
return (int) Math.round((Math.random() * maxRange));
}
private int x;
private int y;
private int canvasWidth = 500;
private int canvasHeight = 500;
private boolean upDown;
private int deltaY;
private int radius = 20;
private int red = random(255);
private int green = random(255);
private int blue = random(255);
VerticalBall(int x, int y, int width, int height) {
this(x, y, width, height, false);
}
VerticalBall(int x, int y, int width, int height, boolean upDown) {
this.x = x;
this.y = y;
this.canvasWidth = width;
this.canvasHeight = height;
this.upDown = upDown;
updateDelta();
}
public void draw(Graphics g) {
g.setColor(new Color(red, green, blue));
g.fillOval((int) (x - radius), (int) (y - radius), (int) (2 * radius),
(int) (2 * radius));
}
private void updateDelta() {
final int minimumMovement = 5;
final int maxExtra = 10;
deltaY = minimumMovement + (int) (Math.random() * maxExtra);
}
public void verticalBounce(Container container) {
// controls vertical ball motion
if (upDown) {
y += deltaY;
if (y >= getHeight()) {
upDown = false;
updateDelta();
}
} else {
y += -deltaY;
if (y <= 0) {
upDown = true;
updateDelta();
}
}
}
public int getX() {
return x;
}
public int getY() {
return y;
}
public int getWidth() {
return canvasWidth;
}
public int getHeight() {
return canvasHeight;
}
}
Container.java
import java.awt.Color;
import java.awt.Graphics;
public class Container {
private static final int HEIGHT = 500;
private static final int WIDTH = 500;
private static final Color COLOR = Color.WHITE;
public void draw(Graphics g) {
g.setColor(COLOR);
g.fillRect(0, 0, WIDTH, HEIGHT);
}
}

Basically, because that's where you're telling them to be created...
verticalBalls.add(new VerticalBall(getX(), getY(), canvasWidth, canvasHeight));
getX() and getY() are getting the component's location (which happens to be close enough to 0x0 for arguments sake)...
Instead, you should be using the MouseEvent information...
public void mousePressed(MouseEvent e) {
if (e.getClickCount() >= 2) {
doubleClick = true;
verticalBalls.add(new VerticalBall(e.getX(), e.getY(), canvasWidth, canvasHeight));
System.out.println("double click");
}
}
This will create an issue for your Timer...
Instead you may need to introduce a couple of variables to hold the position information...
final int x = e.getX();
final int y = e.getX();
if (e.getClickCount() >= 2) {
...
} else {
Timer timer = new Timer(waitTime, new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (doubleClick) {
/* we are the first click of a double click */
doubleClick = false;
} else {
count++;
randomBalls.add(new RandomBall(x, y, canvasWidth, canvasHeight));
/* the second click never happened */
System.out.println("single click");
}
}
});
timer.setRepeats(false);
timer.start();
}

You need to use the getX and getY from the MouseEvent, not from the JPanel.
As a sidenote, your use of a separate Thread to periodically update the gui is bad because you can't use separate threads to call swing methods. use a swing Timer instead.

Java Multithread

After making changes based on user suggestions I have taken the following code a few steps further by introducing single/double click recognition. Why are the balls being created in the top left corner and not where the mouse is clicked?
BouncingBalls.java
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
public class BouncingBalls extends JPanel implements MouseListener {
protected List<RandomBall> randomBalls = new ArrayList<RandomBall>(20);
protected List<VerticalBall> verticalBalls = new ArrayList<VerticalBall>(20);
private Container container;
private DrawCanvas canvas;
private Boolean doubleClick = false;
private final Integer waitTime = (Integer) Toolkit.getDefaultToolkit()
.getDesktopProperty("awt.multiClickInterval");
private static int canvasWidth = 500;
private static int canvasHeight = 500;
public static final int UPDATE_RATE = 30;
int count = 0;
public static int random(int maxRange) {
return (int) Math.round((Math.random() * maxRange));
}
public BouncingBalls(int width, int height) {
canvasWidth = width;
canvasHeight = height;
container = new Container();
canvas = new DrawCanvas();
this.setLayout(new BorderLayout());
this.add(canvas, BorderLayout.CENTER);
this.addMouseListener(this);
start();
}
public void start() {
Thread t = new Thread() {
public void run() {
while (true) {
update();
repaint();
try {
Thread.sleep(1000 / UPDATE_RATE);
} catch (InterruptedException e) {
}
}
}
};
t.start();
}
public void update() {
for (RandomBall ball : randomBalls) {
ball.ballBounce(container);
}
for (VerticalBall ball : verticalBalls) {
ball.verticalBounce(container);
}
}
class DrawCanvas extends JPanel {
public void paintComponent(Graphics g) {
super.paintComponent(g);
container.draw(g);
for (RandomBall ball : randomBalls) {
ball.draw(g);
}
for (VerticalBall ball : verticalBalls) {
ball.draw(g);
}
}
public Dimension getPreferredSize() {
return (new Dimension(canvasWidth, canvasHeight));
}
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
JFrame f = new JFrame("Stack Answer 2");
f.setDefaultCloseOperation(f.EXIT_ON_CLOSE);
f.setContentPane(new BouncingBalls(canvasHeight, canvasWidth));
f.pack();
f.setVisible(true);
}
});
}
#Override
public void mouseClicked(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mousePressed(MouseEvent e) {
if (e.getClickCount() >= 2) {
doubleClick = true;
verticalBalls.add(new VerticalBall(getX(), getY(), canvasWidth, canvasHeight));
System.out.println("double click");
} else {
Timer timer = new Timer(waitTime, new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (doubleClick) {
/* we are the first click of a double click */
doubleClick = false;
} else {
count++;
randomBalls.add(new RandomBall(getX(), getY(), canvasWidth, canvasHeight));
/* the second click never happened */
System.out.println("single click");
}
}
});
timer.setRepeats(false);
timer.start();
}
}
#Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
}
RandomBall.java
import java.awt.Color;
import java.awt.Graphics;
public class RandomBall {
public static int random(int maxRange) {
return (int) Math.round((Math.random() * maxRange));
}
private int x;
private int y;
private int canvasWidth = 500;
private int canvasHeight = 500;
private boolean leftRight;
private boolean upDown;
private int deltaX;
private int deltaY;
private int radius = 20;
private int red = random(255);
private int green = random(255);
private int blue = random(255);
RandomBall(int x, int y, int width, int height) {
this(x, y, width, height, false, false);
}
RandomBall(int x, int y, int width, int height, boolean leftRight, boolean upDown) {
this.x = x;
this.y = y;
this.canvasWidth = width;
this.canvasHeight = height;
this.leftRight = leftRight;
this.upDown = upDown;
updateDelta();
}
public void draw(Graphics g) {
g.setColor(new Color(red, green, blue));
g.fillOval((int) (x - radius), (int) (y - radius), (int) (2 * radius),
(int) (2 * radius));
}
private void updateDelta() {
final int minimumMovement = 5;
final int maxExtra = 10;
deltaY = minimumMovement + (int) (Math.random() * maxExtra);
deltaX = minimumMovement + (int) (Math.random() * maxExtra);
}
public void ballBounce(Container container) {
// controls horizontal ball motion
if (leftRight) {
x += deltaX;
if (x >= getWidth()) {
leftRight = false;
updateDelta();
}
} else {
x += -deltaX;
if (x <= 0) {
leftRight = true;
updateDelta();
}
}
// controls vertical ball motion
if (upDown) {
y += deltaY;
if (y >= getHeight()) {
upDown = false;
updateDelta();
}
} else {
y += -deltaY;
if (y <= 0) {
upDown = true;
updateDelta();
}
}
}
public void verticalBounce(Container container) {
// controls vertical ball motion
if (upDown) {
y += deltaY;
if (y >= getHeight()) {
upDown = false;
updateDelta();
}
} else {
y += -deltaY;
if (y <= 0) {
upDown = true;
updateDelta();
}
}
}
public int getX() {
return x;
}
public int getY() {
return y;
}
public int getWidth() {
return canvasWidth;
}
public int getHeight() {
return canvasHeight;
}
}
VerticalBall.java
import java.awt.Color;
import java.awt.Graphics;
public class VerticalBall {
public static int random(int maxRange) {
return (int) Math.round((Math.random() * maxRange));
}
private int x;
private int y;
private int canvasWidth = 500;
private int canvasHeight = 500;
private boolean upDown;
private int deltaY;
private int radius = 20;
private int red = random(255);
private int green = random(255);
private int blue = random(255);
VerticalBall(int x, int y, int width, int height) {
this(x, y, width, height, false);
}
VerticalBall(int x, int y, int width, int height, boolean upDown) {
this.x = x;
this.y = y;
this.canvasWidth = width;
this.canvasHeight = height;
this.upDown = upDown;
updateDelta();
}
public void draw(Graphics g) {
g.setColor(new Color(red, green, blue));
g.fillOval((int) (x - radius), (int) (y - radius), (int) (2 * radius),
(int) (2 * radius));
}
private void updateDelta() {
final int minimumMovement = 5;
final int maxExtra = 10;
deltaY = minimumMovement + (int) (Math.random() * maxExtra);
}
public void verticalBounce(Container container) {
// controls vertical ball motion
if (upDown) {
y += deltaY;
if (y >= getHeight()) {
upDown = false;
updateDelta();
}
} else {
y += -deltaY;
if (y <= 0) {
upDown = true;
updateDelta();
}
}
}
public int getX() {
return x;
}
public int getY() {
return y;
}
public int getWidth() {
return canvasWidth;
}
public int getHeight() {
return canvasHeight;
}
}
Container.java
import java.awt.Color;
import java.awt.Graphics;
public class Container {
private static final int HEIGHT = 500;
private static final int WIDTH = 500;
private static final Color COLOR = Color.WHITE;
public void draw(Graphics g) {
g.setColor(COLOR);
g.fillRect(0, 0, WIDTH, HEIGHT);
}
}

Change your move method in the Ball class with this one (your conditions are not corrects) :
public void move(Container container) {
if (leftRight) {
x += deltaX;
if (x >= canvasWidth) {
leftRight = false;
updateDelta();
}
} else {
x += -deltaX;
if (x <= 0) {
leftRight = true;
updateDelta();
}
}
if (upDown) {
y += deltaY;
upDown = !(y >= (canvasHeight));
if (y >= (canvasHeight)) {
upDown = false;
updateDelta();
}
} else {
y += -deltaY;
if (y <= 0) {
upDown = true;
updateDelta();
}
}
}
I run it and it works

Your movement logic is overly complicated for simply moving a ball, you should think about conservation of momentum if you want it to bounce off the walls.
The problem is
x >= (Ball.this.getWidth() - canvasWidth / 2)` and `y >= (Ball.this.getHeight() - canvasHeight / 2)
You are creating balls using the first constructor
balls.add(new Ball(x, y, canvasWidth, canvasHeight));
So you are just checking if x>=0 and y>=0, it will keep bouncing around with +- deltax/deltay positions.
A simpler way of making it bounce off walls would be
public void move(Container container) {
if(x>=canvasWidth || x<=0){
deltaX = -1*deltaX;
}
if(y>=canvasHeight || y<=0){
deltaY = -1*deltaY;
}
x+= deltaX;
y+= deltaY;
}

change
public void move(Container container) {
if (leftRight) {
x += deltaX;
if (x >= (Ball.this.getWidth() - canvasWidth / 2)) {
leftRight = false;
updateDelta();
}
} else {
x += -deltaX;
if (x <= 0) {
leftRight = true;
updateDelta();
}
}
if (upDown) {
y += deltaY;
upDown = !(y >= (Ball.this.getHeight() - canvasHeight / 2));
if (y >= (Ball.this.getHeight() - canvasHeight / 2)) {
upDown = false;
updateDelta();
}
} else {
y += -deltaY;
if (y <= 0) {
upDown = true;
updateDelta();
}
}
}
to
public void move(Container container) {
if (leftRight) {
x += deltaX;
if (x >= getWidth()) {
leftRight = false;
updateDelta();
}
} else {
x += -deltaX;
if (x <= 0) {
leftRight = true;
updateDelta();
}
}
if (upDown) {
y += deltaY;
if (y >= getHeight()) {
upDown = false;
updateDelta();
}
} else {
y += -deltaY;
if (y <= 0) {
upDown = true;
updateDelta();
}
}
}

It's because you're using Ball.this.getWidth() and getHeight()...which are set to the canvas height in the constructor. If you use the radius instead, it works. For example:
if ( x >= ( canvasWidth - radius ) )
{
leftRight = false;
updateDelta();
}
And:
if ( y >= ( canvasHeight - radius ) )
{
upDown = false;
updateDelta();
}

How to detect a collision?

I'm having a two image(a cat and a dog) inside the world which is in my Board class. The cat moves in a random direction while the dog move only when I press the arrow keys. My problem now is that how can I make the cat disappear whenever there is a collision between the two images? Any answer or idea would be much appreciated.
Here's what I've tried...
public class Cat extends Sprite implements ImageObserver
{
private java.awt.Image catImage;
private final Board board;
private double x;
private double y;
private double speed;
private double angle;
private boolean visible;
public Cat(Board board, double x, double y, double speed)
{
this.board = board;
this.x = x;
this.y = y;
this.speed = convertToMeterPerSecond(speed);
visible = true;
URL iU = this.getClass().getResource("cat.gif");
ImageIcon icon = new ImageIcon(iU);
catImage = icon.getImage();
}
public Image getImage()
{
return catImage;
}
public void move(long dt)
{
double dt_s = dt / 1e9;
double dx_m = speed * dt_s * Math.sin(angle);
double dy_m = speed * dt_s * Math.cos(angle);
final double right_wall = board.x1_world;
final double up_wall = board.y1_world;
final double down_wall = 0.0;
final double left_wall = 0.0;
x += dx_m;
y += dy_m;
if (x >= right_wall)
{
x = right_wall;
setRandomDirection();
}
if (y > up_wall)
{
y = up_wall;
setRandomDirection();
}
if (x <= left_wall)
{
x = left_wall;
setRandomDirection();
}
if (y < down_wall)
{
y = down_wall;
setRandomDirection();
}
}
public void setRandomDirection()
{
Cat myObject = this;
myObject.setAngle(Math.PI * 2 * Math.random());
}
#Override
public void render(Graphics2D g2d)
{
AffineTransform t = g2d.getTransform();
double height = 0.3; //meter
double width = 0.3; //meter
double cat_footy = height;
double cat_footx = width / 2;
int xx = board.convertToPixelX(x - cat_footx);
int yy = board.convertToPixelY(y + cat_footy);
g2d.translate(xx, yy);
double x_expected_pixels = width * board.meter;
double y_expected_pixels = height * board.meter;
double x_s = x_expected_pixels / ((ToolkitImage) catImage).getWidth();
double y_s = y_expected_pixels / ((ToolkitImage) catImage).getHeight();
double w = ((ToolkitImage) catImage).getWidth();
double h = ((ToolkitImage) catImage).getHeight();
g2d.scale(x_s, y_s);
g2d.drawImage(getImage(), 0, 0, this); // upper left corner
g2d.setColor(Color.BLACK);
g2d.drawRect(0, 0, (int) w, (int) h);
g2d.setTransform(t);
}
public void moveAt(double distance_x, double distance_y)
{
this.x = (int) distance_x;
this.y = (int) distance_y;
}
#Override
public Rectangle getBounds()
{
double w = ((ToolkitImage) catImage).getWidth();
double h = ((ToolkitImage) catImage).getHeight();
return new Rectangle((int) x, (int) y, (int) w, (int) h);
}
public void setAngle(double angle)
{
this.angle = angle;
}
public boolean isVisible()
{
return visible;
}
public void setVisible(Boolean visible)
{
this.visible = visible;
}
#Override
public boolean imageUpdate(Image img, int infoflags, int x, int y, int width, int height)
{
return true;
}
}
for my Cat class
public class Dog extends Sprite implements ImageObserver
{
private java.awt.Image humanImage;
private final Board board;
private double x;
private double y;
private double speed;
private boolean visible;
private double angle;
private double dx_m;
private double dy_m;
public Dog(Board board, double x, double y, double speed)
{
this.board = board;
this.x = x;
this.y = y;
this.speed = convertToMeterPerSecond(speed);
visible = true;
URL iU = this.getClass().getResource("dog.jpg");
ImageIcon icon = new ImageIcon(iU);
dogImage = icon.getImage();
}
public Image getImage()
{
return dogImage;
}
public void keyPressed(KeyEvent e)
{
int key = e.getKeyCode();
if (key == KeyEvent.VK_LEFT)
{
dx_m = -0.3;
}
if (key == KeyEvent.VK_RIGHT)
{
dx_m = 0.3;
}
if (key == KeyEvent.VK_UP)
{
dy_m = 0.3;
}
if (key == KeyEvent.VK_DOWN)
{
dy_m = -0.3;
}
}
public void keyReleased(KeyEvent e)
{
int key = e.getKeyCode();
if (key == KeyEvent.VK_LEFT)
{
dx_m = 0;
}
if (key == KeyEvent.VK_RIGHT)
{
dx_m = 0;
}
if (key == KeyEvent.VK_UP)
{
dy_m = 0;
}
if (key == KeyEvent.VK_DOWN)
{
dy_m = 0;
}
}
#Override
public void move(long dt)
{
double dt_s = dt / 1e9;
final double right_wall = board.x1_world;
final double up_wall = board.y1_world;
final double down_wall = 0.0;
final double left_wall = 0.0;
x += dx_m;
y += dy_m;
if (x <= left_wall)
{
x = left_wall;
}
if (x >= right_wall)
{
x = right_wall;
}
if (y <= down_wall)
{
y = down_wall;
}
if (y >= up_wall)
{
y=up_wall;
}
}
public void setRandomDirection()
{
Dog myObject = this;
myObject.setAngle(Math.PI * 2 * Math.random());
}
#Override
public void render(Graphics2D g2d)
{
AffineTransform t = g2d.getTransform();
final double dogHeight = 1.6;// meter
final double dogWidth = 1.8; //meter
final double foot_position_y = dogHeight;
final double foot_position_x = dogWidth / 2;
int xx = board.convertToPixelX(x - foot_position_x); // to find the upper-left corner
int yy = board.convertToPixelY(y + foot_position_y); // to find the upper-left corner
g2d.translate(xx, yy);
// ratio for actual Image size
double x_expected_pixels = dogHeight * board.meter;
double y_expected_pixels = dogWidth * board.meter;
double w = ((ToolkitImage) dogImage).getWidth();
double h = ((ToolkitImage) dogImage).getHeight();
double x_s = x_expected_pixels / w;
double y_s = y_expected_pixels / h;
g2d.scale(x_s, y_s);
g2d.drawImage(getImage(), 0, 0, this); // upper left corner
g2d.setColor(Color.BLACK);
g2d.drawRect(0, 0, (int) w, (int) h);
g2d.setTransform(t);
}
#Override
public void moveAt(double distance_x, double distance_y)
{
this.x = distance_x;
this.y = distance_y;
}
public void setAngle(double angle)
{
this.angle = angle;
}
#Override
public Rectangle getBounds()
{
double width = ((ToolkitImage) dogImage).getWidth();
double height = ((ToolkitImage) dogImage).getHeight();
return new Rectangle((int) x, (int) y, (int) width, (int) height);
}
public boolean isVisible()
{
return visible;
}
public void setVisible(Boolean visible)
{
this.visible = visible;
}
#Override
public boolean imageUpdate(Image img, int infoflags, int x, int y, int width, int height)
{
return true;
}
}
for my Dog class
public class Board extends Canvas
{
private Cat cat;
public static final long SECOND = 1000 * 1000 * 1000;
public double meter;//PIXEL
private HumanBeing humanBeing;
/**
* ascending from 0 to N
* 0 : most far way...
* N : is the closest (painted the last)
*/
private final java.util.List<Sprite> z_sorted_sprites = new ArrayList<Sprite>();
private BufferStrategy strategy;
int x0_pixel;
int y0_pixel;
int x1_pixel;
int y1_pixel;
double x1_world;
double y1_world;
private final Frame frame;
public Board(Frame frame, double meter)
{
addKeyListener(new TAdapter());
this.frame = frame;
this.setIgnoreRepaint(true);
this.meter = meter;
setFocusable(true);
dog = new Dog(this, 5, 5, 40);
init();
addComponentListener(new ComponentAdapter()
{
#Override
public void componentResized(ComponentEvent e)
{
render();
}
});
}
public void init()
{
z_sorted_sprites.add(new Cat(this, 0, 0, 30));
z_sorted_sprites.add(new Cat(this, 1, 1, 10));
z_sorted_sprites.add(new Cat(this, 2, 2, 20));
z_sorted_sprites.add(new Cat(this, 3, 3, 100));
}
public void render()
{
setupStrategy();
x0_pixel = 0;
y0_pixel = 0;
x1_pixel = getWidth();
y1_pixel = getHeight();
x1_world = x1_pixel / meter;
y1_world = y1_pixel / meter;
Graphics2D g2d = (Graphics2D) strategy.getDrawGraphics();
g2d.setBackground(Color.lightGray);
g2d.clearRect(0, 0, x1_pixel, y1_pixel);
g2d.setColor(Color.BLACK);
for (double x = 0; x < x1_world; x++)
{
for (double y = 0; y < y1_world; y++)
{
int xx = convertToPixelX(x);
int yy = convertToPixelY(y);
g2d.drawOval(xx, yy, 2, 2);
}
}
for (Sprite z_sorted_sprite : z_sorted_sprites)
{
z_sorted_sprite.render(g2d);
}
dog.render(g2d);
g2d.dispose();
strategy.show();
Toolkit.getDefaultToolkit().sync();
}
public int convertToPixelX(double distance)
{
return (int) (distance * meter);
}
public int convertToPixelY(double y_world)
{
return (int) (y1_pixel - (y_world * meter));
}
public void onZoomUpdated(int value)
{
meter = value;
render();
}
private void setupStrategy()
{
if (strategy == null)
{
this.createBufferStrategy(2);
strategy = this.getBufferStrategy();
}
}
public void start() throws InterruptedException
{
long prevLoopStart = System.nanoTime();
Avg avg = new Avg();
while (true)
{
final long loopStart = System.nanoTime();
final long dt = loopStart - prevLoopStart;
for (Sprite sprite : z_sorted_sprites)
{
sprite.move(dt);
}
dog.move(dt);
render();
frame.onFpsUpdated(1.0 / dt * SECOND, avg.add(loopStart));
final long elapsed_ns = System.nanoTime() - loopStart;
long expected_elapsed_ms = 1000 / 60;
long elapsed_ms = (long) (elapsed_ns / (1000.0 * 1000.0));
long sleep_ms = expected_elapsed_ms - elapsed_ms;
if (sleep_ms > 0)
{
Thread.sleep(sleep_ms /* ms */);
}
prevLoopStart = loopStart;
}
}
private void checkCollision()
{
Rectangle r2 = cat.getBounds();
Rectangle r3 = dog.getBounds();
if (r3.intersects(r2))
{
dog.setVisible(false);
cat.setVisible(false);
}
}
static class Avg
{
java.util.List<Long> ticks = new ArrayList<Long>();
/**
* #return the rate for the last second
*/
int add(long tick)
{
ticks.add(0, tick);
if (ticks.size() < 2)
{
return -1;
}
int last = -1;
for (int pos = ticks.size() - 1; pos >= 0; pos--)
{
if (tick - ticks.get(pos) <= SECOND)
{
last = pos;
break;
}
}
while (ticks.size() - 1 > last)
{
ticks.remove(ticks.size() - 1);
}
return ticks.size();
}
}
private class TAdapter extends KeyAdapter
{
public void keyReleased(KeyEvent e)
{
dog.keyReleased(e);
}
public void keyPressed(KeyEvent e)
{
dog.keyPressed(e);
}
}
}
For my Board class
public abstract class Sprite
{
public Sprite()
{
}
public Rectangle getBounds()
{
return new Rectangle();
}
public static double convertToMeterPerSecond(double speed)
{
// 25 km / hour
// 25000 m / 3600 s
return speed / 3.6;
}
public abstract void move(long dt);
public abstract void moveAt(double distance_x, double distance_y);
public abstract void render(Graphics2D g2d);
public abstract void setVisible(Boolean visible);
}
For my sprite class
public boolean checkCollisions(java.util.List<Sprite> sprites)
{
Dog dog = this;
Rectangle r1 = dog.getBounds();
for (int i = 0; i < sprites.size(); i++)
{
Rectangle r2 = sprites.get(i).getBounds();
if (r1.intersects(r2))
{
sprites.remove(i);
}
}
return true;
}

You have given a lot of code, but as Sibbo said, I don't see your checkCollisions method being called anywhere. It should be called every loop of your game.
Check out this tutorial, specifically look at the gameLoop method in the Game class. When I made a sprite based game that required a lot of collision detection this tutorial helped me out a lot.

I'd implement method that detects that positions of cat and dog overlap in the board class since board is the only instance that "knows" both dog and cat. The implementation is pretty simple: compare coordinates (something like dog.x + dog.width < cat.x || dog.x > cat.x + cat.width etc, etc.
If future you can implement more generic method, so if you will wish to add mouse you will be able to reuse the code.

The dog class doesn't overwrite the getBounds() method. So everytime you check if the rectangle (0, 0, 0, 0) intersects for example (3, 4, 50, 50) (if the cat is at (3, 4)).
Where do you call the checkCollision() method?
EDIT:
Create a method like your checkCollision() in your Dog class:
public boolean checkCollision(Sprite s) {...}
It should return true, when a collision is detected. Call this method from the Board.start() method for every Sprite in z_sorted_sprites. IF it returns true, remove the Sprite from the list.