import java.awt.*;
import javax.swing.*;
public class ball_bounce extends JApplet
{
private ball b1=new ball(150,250,2,4,50,Color.BLUE);
private ball b2=new ball(350,250,-3,2,50,Color.RED);
private ball b3=new ball(150,350,4,6,50,Color.MAGENTA);
private ball b4=new ball(350,350,-5,3,50,Color.YELLOW);
private ball b5=new ball(350,350,-5,3,100,Color.GREEN);
private Image a;
public ball_bounce() { }
public void init()
{
setBackground(Color.cyan);
}
public void start() { }
public void paint(Graphics g)
{
Dimension d = getSize();
checkOffscreenImage();
Graphics offG = a.getGraphics();
offG.setColor(getBackground()); //clear screen
offG.fillRect(0, 0, 500, 500); //clear screen
// Draw into the offscreen image.
paintOffscreen(a.getGraphics());
// Put the offscreen image on the screen.
g.drawImage(a, 0, 0, null);
try{Thread.sleep(10);}
catch(Exception e){}
repaint();
}
private void checkOffscreenImage()
{
Dimension d = getSize();
if (a == null ||
a.getWidth(null) != d.width ||
a.getHeight(null) != d.height) {
a = createImage(d.width, d.height);
}
}
public void paintOffscreen(Graphics g) {
ball[] B={b1,b2,b3,b4};
for(int a=0;a<4;a++)
B[a].moveBall(g);
b5.moveBall(g);
for(int a=0;a<4;a++)
for(int b=0;b<4;b++)
{
if(b!=a)
B[a].ballCollision(B[b]);
}
for(int a=0;a<4;a++) {
int b=b5.x_speed;
b5.ballCollision(B[a]);
if(b!=b5.x_speed) b5.ball_size-=5;
if(0>=b5.ball_size) b5.ball_size=100;
}
}
}
*************************************************
import java.awt.*;
import javax.swing.*;
import java.math.*;
public class ball extends JApplet
{
public int x_loc,y_loc,x_speed,y_speed,ball_size;
private Color ball_color;
public ball(int x, int y, int xs,
int ys, int s, Color c)
{
x_loc=x;
y_loc=y;
x_speed=xs;
y_speed=ys;
ball_size=s;
ball_color=c;
}
private void drawBall(Graphics g)
{
g.setColor(ball_color);
g.fillOval(x_loc,y_loc,ball_size,ball_size);
}
public void moveBall(Graphics g)
{
x_loc+=x_speed;
y_loc+=y_speed;
drawBall(g);
wallCollision();
}
private void wallCollision()
{
if(x_loc<=0 || x_loc>=500-ball_size) x_speed*=-1;
if(y_loc<=0 || y_loc>=500-ball_size) y_speed*=-1;
}
public void ballCollision(ball q)
{
int xd=(this.x_loc+this.ball_size)-(q.x_loc+q.ball_size);
int yd=(this.y_loc+this.ball_size)-(q.y_loc+q.ball_size);
double xs=xd*xd;
double ys=yd*yd;
int h=(int)(Math.sqrt(xs+ys));
if(h<=this.ball_size/2+q.ball_size/2)
{
x_speed*=-1;
y_speed*=-1;
}
}
}
