1.7键盘控制小球

import java.awt.*;

import java.awt.event.*;

public class MyBall2{

public static void main(String[] args){

Frame w = new Frame();

w.setSize(300, 400);

MyPanel mp = new MyPanel();

w.add(mp);

w.addKeyListener(mp);

mp.addKeyListener(mp);

w.show();

}

}

class MyPanel extends Panel implements KeyListener{

int x = 30;

int y = 30;

public void paint(Graphics g){

g.fillOval(x, y, 20, 20);

}

@Override

public void keyPressed(KeyEvent arg0){

if(arg0.getKeyCode() == 37){

x--;

}

if(arg0.getKeyCode() == 38){

y--;

}

if(arg0.getKeyCode() == 39){

x++;

}

if(arg0.getKeyCode() == 40){

y++;

}

repaint();

}

@Override

public void keyReleased(KeyEvent arg0){

}

@Override

public void keyTyped(KeyEvent arg0){

}

}