题目：实现 使用上下左右键控制小球移动
public class Test12 extends JFrame { MyPanel mp = new MyPanel(); public static void main(String[] args) { // TODO Auto-generated method stub Test12 t12 = new Test12(); } public Test12(){ mp = new MyPanel(); this.add(mp); //实现监听 this.addKeyListener(mp); this.setSize(250, 300); this.setLocation(300, 120); this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); this.setVisible(true); } } class MyPanel extends JPanel implements KeyListener{ Boll boll = new Boll(10,10); int x= boll.getX(); int y= boll.getY(); public void paint(Graphics g){ super.paint(g); //画出一个小球 g.setColor(Color.red); g.fillOval( x,y, 20, 20); } @Override public void keyPressed(KeyEvent e) { // TODO Auto-generated method stub if(e.getKeyCode()==KeyEvent.VK_UP){ y--; }else if(e.getKeyCode()==KeyEvent.VK_DOWN){ y++; }else if(e.getKeyCode()==KeyEvent.VK_LEFT){ x--; }else if(e.getKeyCode()==KeyEvent.VK_RIGHT){ x++; } this.repaint(); } @Override public void keyReleased(KeyEvent e) { // TODO Auto-generated method stub } @Override public void keyTyped(KeyEvent e) { // TODO Auto-generated method stub } } class Boll{ public int getX() { return x; } public void setX(int x) { this.x = x; } public int getY() { return y; } public void setY(int y) { this.y = y; } int x=0; public Boll(int x, int y) { super(); this.x = x; this.y = y; } int y=0; }
实现事件监听的步骤：
1、实现相应的接口（ActionListener，KeyListener，MouseListener，WindowsListener）
在哪个类上面实现接口？需要来监听的那个类！
2、把接口的处理方法重写（Override）
3、把事件源注册监听
