Java Bouncing Ball

Question

I am trying to write a Java application which draws multiple balls on screen which bounce off of the edges of the frame. I can successfully draw one ball. However when I add

Answer 1

package BouncingBallApp.src.copy;
import java.awt.*;


public class Ball {
    private Point location;
    private int radius;
    private Color color;
    private int dx, dy;
    //private Color[] ballArr;

    public Ball(Point l, int r, Color c){
        location = l;
        radius = r;
        color = c;
    }

    public Ball(Point l, int r){
        location = l;
        radius = r;
        color = Color.RED;

    }

    public Point getLocation() {
        return location;
    }

    public void setLocation(Point location) {
        this.location = location;
    }

    public int getRadius() {
        return radius;
    }

    public void setRadius(int radius) {
        this.radius = radius;
    }

    public Color getColor() {
        return color;
    }

    public void setColor(Color color) {
        this.color = color;

    }

    public void setMotion(int dx, int dy){
        this.dx = dx;
        this.dy = dy;
    }

    public void move(){
        location.translate(dx, dy);
    }

    public void moveTo(int x, int y){
        location.move(x, y);
    }

    public void paint (Graphics g) {
        g.setColor (color);
        g.fillOval (location.x-radius, location.y-radius, 2*radius, 2*radius);
    }

    public void reclectHoriz() {
        dy = -dy;       
    }   

    public void reclectVert() {
        dx = -dx;       
    }
}







package BouncingBallApp.src.copy;

public class MyApp {

    public static void main(String[] args) {
        MyFrame frm = new MyFrame(10);
        frm.setVisible(true);           

        for (int i=0; i<1000; i++){
            frm.stepTheBall();
        }
    }
}





package BouncingBallApp.src.copy;


import java.awt.Color;
import java.awt.Graphics;
import java.awt.Point;
import java.util.Random;

import javax.swing.JFrame;


public class MyFrame extends JFrame {
    public final int FRAMEWIDTH = 600;
    public final int FRAMEHEIGHT = 400;

    private Ball[] ballArr;

    private Random random =new Random ();
    private Color[] colors={Color.RED,Color.blue,Color.yellow}; 
    private int ballCnt;

    public MyFrame(int ballCnt){
        super();
        setSize(FRAMEWIDTH, FRAMEHEIGHT);
        setTitle("My Bouncing Ball Application");

        ballArr = new Ball[ballCnt];
        this.ballCnt = ballCnt;
         int c;

        for (int i=0; i < ballCnt; i++){
            int bcn =random.nextInt(colors.length);
            Color ballcolor=colors[bcn];
            ballArr[i] = new Ball(new Point(50,50),c=(int) (Math.random()*10+3)%8,ballcolor);


            int ddx = (int) (Math.random()*10+2)%8;
            int ddy = (int) (Math.random()*10+2)%8;         
            ballArr[i].setMotion(ddx, ddy); 
            //c++;
        }
    }

    public void paint(Graphics g){
        super.paint(g);
        for (int i=0; i < ballCnt; i++){
            ballArr[i].paint(g);    
        }
    }

    public void stepTheBall(){
        for (int i=0; i < ballCnt; i++){        
            ballArr[i].move();

            Point loc = ballArr[i].getLocation();

            if (loc.x < ballArr[i].getRadius() ||
                loc.x > FRAMEWIDTH-ballArr[i].getRadius()){
                ballArr[i].reclectVert();
            }

            if (loc.y < ballArr[i].getRadius() ||
                    loc.y > FRAMEHEIGHT-ballArr[i].getRadius()){
                ballArr[i].reclectHoriz();
            }
        }   
        repaint();
        try {
            Thread.sleep(20);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

}