Many Bouncing Balls Program

Question

I am trying to create a program that can use one method to create many bouncing balls.I want each ball to function independently of each other.
The problem I am having is that when I call my BouncingBall () method three times, it only creates one ball that moves randomly instead of three.
If you have any idea of how to tackle this problem I would really appreciate if you shared them with me. I am relatively new to java.
I read that threads might be a good option to work on this problem but I am not sure how to use them.
*(Code Starts)*
import acm.graphics.*;
import acm.program.*;
import acm.util.*;
import java.awt.*;
import java.awt.event.*;
public class BouncingBalls extends GraphicsProgram {
     public void run(){
          BouncingBall(50, 50);
          BouncingBall(100, 100);
          BouncingBall(300, 300);
     public void BouncingBall(double width, double height) {
          //Create variables for x and y position of balls
          double xPosition = getWidth()/2;
          double yPosition = getHeight()/2;
          //Create Ball
          GOval Ball = new GOval (xPosition, yPosition, width, height);
          add (Ball);
          // Initialize variables for use in Random movement method
          double xMoveBall = rgen.nextDouble(-4.0, 4.0);
          double yMoveBall = rgen.nextDouble(-4.0, 4.0);
          //Ball's Random Movement
          while (true) {     
                    Ball.move(xMoveBall,yMoveBall);
                    pause(10);
                         xPosition += xMoveBall;
                         yPosition += yMoveBall;
               //Ball's Collisions     with walls
               if (xPosition >= (getWidth() - width)) {
                    xMoveBall = -(xMoveBall);
                    pause(10);
               if (xPosition <= 0){
                    xMoveBall = -(xMoveBall);
                    pause(10);
               if (yPosition <= 0){
                    yMoveBall = -(yMoveBall);
                    pause(10);
               if (yPosition >= getHeight() - height){
                    yMoveBall = -(yMoveBall);
                    pause(10);
     private RandomGenerator rgen = RandomGenerator.getInstance();{}
*(Code Ends)*

Answer 1

Hi,
I have been experimenting with threads for the last couple of days. Here is the code I have been working on. I explain what I am trying to do below it:
import acm.graphics.*;
import acm.program.*;
import acm.util.*;
import java.awt.*;
import java.awt.event.*;
public class BB5 extends GraphicsProgram implements Runnable{
     // Debbuging Label
     private GLabel label = new GLabel("");
     //Initialize variables for ball's position
     private double xPosition = getWidth()/2;
     private double yPosition = getHeight()/2;
     //Initialize variables for use in Random movement method
     private double yMoveBall;
     private double xMoveBall;
     //Initialize variables for width and height of ball, so that they can be used in both metods: bounce() and CreateBall()
     private double width;
     private double height;
     public void mouseClicked (MouseEvent e){
          new Thread(this).start();
     public void run() {
          CreateBall(50,50).bounce();
     public void CreateBall(double x, double y) {
          //Create variables for x and y position of balls
             xPosition = getWidth()/2;
             yPosition = getHeight()/2;
          //Create Ball
          x = width;
          y = height;
          GOval Ball = new GOval (xPosition, yPosition, width, height);
          add (Ball);
     public void bounce() {     
     yMoveBall = rgen.nextDouble(-4.0, 4.0);
     xMoveBall = rgen.nextDouble(-4.0, 4.0);
          //Ball's Random Movement
          while (true){
               //Put thread to sleep for 5 milliseconds so that other balls can use bounce()
               try { Thread.sleep(5); } catch(InterruptedException e) {}
                    //Move Ball created in previous methods
                    Ball.move(xMoveBall,yMoveBall);
                    pause(10);
                         xPosition += xMoveBall;
                         yPosition += yMoveBall;
                         label.setLabel(""+xPosition); add (label, 50, 50);
               //Ball's Collisions     with walls
               if (xPosition >= (getWidth() - width)) {
                    xMoveBall = -(xMoveBall);
                    pause(10);
               if (xPosition  <= 0){
                    xMoveBall = -(xMoveBall);
                    pause(10);
               if (yPosition  <= 0){
                    yMoveBall = -(yMoveBall);
                    pause(10);
               if (yPosition  >= getHeight() - height){
                    yMoveBall = -(yMoveBall);
                    pause(10);
     private RandomGenerator rgen = RandomGenerator.getInstance();{}
}The idea is that I have a method that creates the ball CreateBall(), and another that bounces the ball bounce().
My init method creates one ball. Then, when I click the mouse, I create a new thread which applies the bounce method to the ball by running the run method.
Inside the bounce method, I have a thread sleep so that other threads can be started.
Eventually, what I would like to do, is that everytime I click the mouse, a new ball is created and the bounce is applied to it.
I am also having trouble with getting the ball from my CreateBall() method, to work inside my bounce().
Can you please help me understand what might be wrong with my code?
Thank you!