bouncing Balls

[mystery81]

Hi !

I am new to Java and trying to write a program with a few bouncing balls ! after running the application i only get one ball bouncing. here is the code any idea what 2 do in order to have all the balls in the panel ?

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

/**
* BouncePanel represents a canvas (drawing area) for objects of type Ball. A
* timer-object periodically updates the canvas (in the run method), by moving
* and repainting the objects.
*/

public class BouncePanel extends JPanel implements ActionListener,
MouseMotionListener {

private int width = 1800, height = 900;
private Ball[] theBall ;
private Rectangle pad; // The to bounce of the ball

private Timer timer;

public BouncePanel() {
this.setPreferredSize(new Dimension(width, height));
this.setBackground(Color.lightGray);
//Rectangle bounds =new Rectangle (0,0,width ,height);


// Create and initialize a ball
theBall=new Ball[4];
for (int k=0 ; k<theBall.length ;k++){

theBall[k] = new Ball(4 ,4 ,6 , Color.green);
theBall[k].setVelocity(15, 15);
}
// Create the pad
pad = new Rectangle(width / 2, height - 40, 40, 5);

// Initialize event handling (mouse motion)
this.addMouseMotionListener(this);

}

public void startAnimation() {
// Create, and start, the timer-object responsible for the animation
timer = new Timer(10, this); // Signal every 10 milliseconds
// (actionPerformed is called)
timer.start();
}

/**
* Update the position of the ball and repaint. This method is called each
* time the Timer produces an event.
*/
public void actionPerformed(ActionEvent event) {
// Is the ball outside the panel?
for (int k=0 ; k<theBall.length ;k++){
constrainBall(theBall[k]);
// Move the ball
theBall[k].move();
// Check ball against the pad
checkForCollisionWithPad(theBall[k]);
// Draw the ball (request to call paintComponent(g))
repaint();
}

}
/**
* Define what to draw. Called by repaint().
*/
public void paintComponent(Graphics g) {
super.paintComponent(g);

// The pad
g.setColor(Color.white);
g.fillRect(pad.x, pad.y, pad.width, pad.height);
for (int k=0 ; k<theBall.length ; k++){
// The ball
theBall[k].paint(g);
}
}
/**
* Called when the mouse is dragged (left button down)
*/
public void mouseDragged(MouseEvent e) {
Point point = e.getPoint();

// Keep the pad inside the panel
if (point.x < 0) {
pad.x = 0;
} else if (point.x > this.getWidth() - pad.width) {
pad.x = this.getWidth() - pad.width;
} else {
pad.x = point.x;
}
}

public void mouseMoved(MouseEvent e) {
// Do nothing
}

/**
* Check if the ball collides with the pads upper edge. If so, bounce the
* ball vertically.
*/
private void checkForCollisionWithPad(Ball ball) {
double radius = ball.getRadius();
double x1 = ball.getX(), y1 = ball.getY();
double dx = ball.getDx(), dy = ball.getDy();
double y2 = y1 + ball.getDy();
// Does the line between the current and the next position of the ball
// intersect the upper edge of the pad? If so - bounce off.
if ((y1 + radius <= pad.y && y2 + radius >= pad.y)
|| (y2 - radius <= pad.y && y1 - radius >= pad.y)) {
double intersectX = x1 - dx * (y1 - pad.y) / dy;
if (intersectX >= pad.x && intersectX <= pad.x + pad.width) {
ball.setVelocity(dx, -dy);
}
}
}

/**
* Keep the ball inside the panel/canvas
*/
private void constrainBall(Ball ball) {
double x = ball.getX(), y = ball.getY();
double dx = ball.getDx(), dy = ball.getDy();
double radius = ball.getRadius();

// If outside the box - calculate new dx and dy
if (x < radius)
dx = Math.abs(dx);
else if (x > width - radius)
dx = -Math.abs(dx);
if (y < radius)
dy = Math.abs(dy);
else if (y > height - radius)
dy = -Math.abs(dy);

ball.setVelocity(dx, dy);
}

private static final long serialVersionUID = 1L;
}







import java.awt.Color;
import java.awt.Graphics;


/**
* A representation of a ball moving inside a box. The method paint(Graphics g)
* makes it possible to draw a ball in a graphical environment.
*/

public class Ball {

private double x, y; // position of center
private double dx, dy; // velocity
private double radius;
private Color color;
//private Rectangle box;
public Ball(double x0, double y0, double r ,Color col ) { //#
x = x0;
y = y0;
radius = 10;
color = col;
}

public void setColor (Color col){

color = col ;

}


//public void setBoundingBox(Rectangle box_){
// box = box_;




public double getX() {
return x;
}

public double getY() {
return y;
}

public double getRadius() {
return radius;
}

public double getDx() {
return dx;
}

public double getDy() {
return dy;
}

public void setVelocity(double dx_, double dy_) {
dx = dx_;
dy = dy_;
}

/**
* Move the ball one step (dx, dy)
*/
public void move() {
x += dx;
y += dy;
}

/**
* Draw the ball on the screen
*/
public void paint(Graphics g) {
g.setColor(color);
g.fillOval((int) (x - radius), (int) (y - radius), (int) (2 * radius),
(int) (2 * radius));
}
}



import javax.swing.*;

/**
* Main creates a window (JFrame) containing the BouncePanel.
*/

public class Juggler {
public static void main(String[] args) {
// Create a window (frame)
JFrame frame = new JFrame("The Juggler");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOS E);
frame.setResizable(false);

// Create a canvas (BouncePanel) and add it to the window.
BouncePanel panel = new BouncePanel();
frame.add(panel);
frame.pack();

frame.setVisible(true);
panel.startAnimation();
}
}

[Norm]

Pleae edit your post and wrap the code in code tags. See: BB Code List - Java Programming Forum

[JavaAdviser]

All the balls are in the panel. :)

The thing is, that they are perfectly overlapping.

I've edited the move() method in the Ball class like this.

/**
   * Move the ball one step (dx, dy)
   */
  public void move() {
    x += dx + (int) (Math.random() * 10);
    y += dy + (int) (Math.random() * 10);
  }

and then you will see multiple balls.

[mystery81]

Thank u sir , may the lord bless u with new methods !!! :D

[mystery81]

tanx tanx :D :D