Copy following code and compile
import java.awt.*;
import java.awt.event.KeyEvent;
import javax.swing.JFrame;
import java.util.Random;
import java.util.Timer;
public class BouncingBall extends Canvas
{
int x, y, dx, dy;
Color cur;
Random rng;
boolean flashing = false;
public static void main( String[] args )
{
JFrame win = new JFrame("BouncingBall");
win.setSize(1010,735);
win.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
win.add( new BouncingBall() );
win.setVisible(true);
}
public BouncingBall()
{
enableEvents(java.awt.AWTEvent.KEY_EVENT_MASK);
requestFocus();
x = 500;
y = 350;
dx = 5;
dy = 5;
cur = Color.black;
rng = new Random();
Timer t = new Timer(true);
t.schedule( new java.util.TimerTask()
{
public void run()
{
doStuff();
repaint();
}
}, 10, 10);
}
public void paint( Graphics g )
{
g.setColor(cur);
g.fillOval(x, y, 20, 20);
}
public void processKeyEvent(KeyEvent e)
{
if ( e.getID() == KeyEvent.KEY_PRESSED )
{
if ( e.getKeyCode() == KeyEvent.VK_SPACE )
{
flashing = ! flashing;
}
}
}
public void doStuff()
{
x += dx;
y += dy;
// and bounce if we hit a wall
if ( x < 0 || x+20 > 1000 )
dx = -dx;
if ( y < 0 || y+20 > 700 )
dy = -dy;
if ( flashing )
{
int r = rng.nextInt(256);
int g = rng.nextInt(256);
int b = rng.nextInt(256);
cur = new Color(r,g,b);
}
}
public boolean isFocusable() { return true; }
}
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