Java Source Codes

bounce

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

public class Bounce
{ public static void main(String[] args)
{ JFrame frame = new BounceFrame();
frame.show();
}
}

class BounceFrame extends JFrame
{ public BounceFrame()
{ setSize(300, 200);
setTitle("Bounce");

addWindowListener(new WindowAdapter()
{ public void windowClosing(WindowEvent e)
{ System.exit(0);
}
} );

Container contentPane = getContentPane();
canvas = new JPanel();
contentPane.add(canvas, "Center");
JPanel p = new JPanel();
addButton(p, "Start",
new ActionListener()
{ public void actionPerformed(ActionEvent evt)
{ Ball b = new Ball(canvas);
b.bounce();
}
});

addButton(p, "Close",
new ActionListener()
{ public void actionPerformed(ActionEvent evt)
{ System.exit(0);
}
});
contentPane.add(p, "South");
}

public void addButton(Container c, String title,
ActionListener a)
{ JButton b = new JButton(title);
c.add(b);
b.addActionListener(a);
}

private JPanel canvas;
}

class Ball
{ public Ball(JPanel b) { box = b; }

public void draw()
{ Graphics g = box.getGraphics();
g.fillOval(x, y, XSIZE, YSIZE);
g.dispose();
}

public void move()
{ Graphics g = box.getGraphics();
g.setXORMode(box.getBackground());
g.fillOval(x, y, XSIZE, YSIZE);
x += dx;
y += dy;
Dimension d = box.getSize();
if (x < 0)
{ x = 0; dx = -dx; }
if (x + XSIZE >= d.width)
{ x = d.width - XSIZE; dx = -dx; }
if (y < 0)
{ y = 0; dy = -dy; }
if (y + YSIZE >= d.height)
{ y = d.height - YSIZE; dy = -dy; }
g.fillOval(x, y, XSIZE, YSIZE);
g.dispose();
}

public void bounce()
{ draw();
for (int i = 1; i <= 1000; i++)
{ move();
try { Thread.sleep(5); }
catch(InterruptedException e) {}
}
}

private JPanel box;
private static final int XSIZE = 10;
private static final int YSIZE = 10;
private int x = 0;
private int y = 0;
private int dx = 2;
private int dy = 2;
}

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