关于 java 移动小球 问题....快崩溃咯..

package com.练习;

import java.awt.*;

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

public class Box
{
public static void main(String[] args)
{
new MyFrame();
}
}
class MyFrame extends JFrame
{
MyPanel mp = null;
public MyFrame()
{
mp = new MyPanel();
this.add(mp);
this.setSize(400, 300);
this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
class MyPanel extends JPanel implements Runnable
{
int x = 100, y = 100;
public MyPanel()
{
}
public void paint(Graphics g)
{
super.paint(g);
g.setColor(new Color(64, 64, 64));
g.fillRect(0, 0, 400, 300);
g.setColor(Color.YELLOW);
g.fillOval(x, y, 15, 15);
}
@Override
public void run()
{
}
}

救命啊... 写到这儿 卡住了, 脑筋怎么也转不过来,
想实现 运行 就在面板上 出现一个小球 自动移动 遇墙 则换方向,

我现在的问题是, 不知道线程放在哪
思路应该是 g.fillOval(x, y, 15, 15); 利用repaint();函数重绘 不知道找函数要放到哪去才合适
T.T x,y 也得放在线程里 , 结果不会取出来 -0 - 悲剧... 想撞墙!....

恳求高手们 指点明路...

[解决办法]
给你参考下，一个用applet写的代码：
最下面那个类是主类，中间是主要;

Ball类：
import javax.swing.Timer;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class Ball extends JPanel {
private int delay = 10;

// Create a timer with delay 1000 ms
private Timer timer = new Timer(delay, new TimerListener());

private int x = 0; private int y = 0; // Current ball position
private int radius = 5; // Ball radius
private int dx = 2; // Increment on ball's x-coordinate
private int dy = 2; // Increment on ball's y-coordinate

public Ball() {
timer.start();
}

private class TimerListener implements ActionListener {
/** Handle the action event */
public void actionPerformed(ActionEvent e) {
repaint();
}
}

protected void paintComponent(Graphics g) {
super.paintComponent(g);

g.setColor(Color.red);

// Check boundaries
if (x < radius) dx = Math.abs(dx);
if (x > getWidth() - radius) dx = -Math.abs(dx);
if (y < radius) dy = Math.abs(dy);
if (y > getHeight() - radius) dy = -Math.abs(dy);

// Adjust ball position
x += dx;
y += dy;
g.fillOval(x - radius, y - radius, radius * 2, radius * 2);
}

public void suspend() {
timer.stop(); // Suspend timer
}

public void resume() {
timer.start(); // Resume timer
}

public void setDelay(int delay) {
this.delay = delay;
timer.setDelay(delay);
}
}
——————————————————————————————————————————
BallControl 类：
mport javax.swing.*;
import java.awt.event.*;
import java.awt.*;

public class BallControl extends JPanel {
private Ball ball = new Ball();
private JButton jbtSuspend = new JButton("Suspend");
private JButton jbtResume = new JButton("Resume");
private JScrollBar jsbDelay = new JScrollBar();

public BallControl() {
// Group buttons in a panel
JPanel panel = new JPanel();
panel.add(jbtSuspend);
panel.add(jbtResume);

// Add ball and buttons to the panel
ball.setBorder(new javax.swing.border.LineBorder(Color.red));
jsbDelay.setOrientation(JScrollBar.HORIZONTAL);
ball.setDelay(jsbDelay.getMaximum());
setLayout(new BorderLayout());
add(jsbDelay, BorderLayout.NORTH);
add(ball, BorderLayout.CENTER);
add(panel, BorderLayout.SOUTH);

// Register listeners
jbtSuspend.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
ball.suspend();
}
});
jbtResume.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {

ball.resume();
}
});
jsbDelay.addAdjustmentListener(new AdjustmentListener() {
public void adjustmentValueChanged(AdjustmentEvent e) {
ball.setDelay(jsbDelay.getMaximum() - e.getValue());
}
});
}
}

-------------------------------

BounceBallApp 类：
import java.awt.*;
import javax.swing.*;

public class BounceBallApp extends JApplet {
public BounceBallApp() {
add(new BallControl());
}

public static void main(String[] args) {
BounceBallApp applet = new BounceBallApp();
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("BounceBallApp");
frame.add(applet, BorderLayout.CENTER);
frame.setSize(400, 320);
frame.setVisible(true);
}
}