请给我看一下！当小球不动后，我在单击“复位”按钮后可以让小球回到原位，单击事件怎么写!还有如果可以的话帮我加个停止按钮，在单击时可以随时终止小球运动！
谢谢了~~
[code="java"]import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Line2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class BallBall extends JFrame
{
public BallBall() //TwoBall构造
{
super("演示");
this.setSize(1000, 750);
this.setLocation(20, 20);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
Ball jpanel= new Ball();
this.add(jpanel);
this.setVisible(true);
}
class Ball extends JPanel implements ActionListener
{
private int T;
double v1; //上抛初速 5000<v1<11000
double v2;
double x21, y21, x22, y22; // 斜抛坐标
double x1,y1; //上抛运动坐标
double g=9.8;
int Q=10000;
Image a,b;
private JTextField time;
private JTextField yv;
private JTextField xv;
private JButton start,back;
private Thread thread1;
private Thread thread2;
public Ball()
{
this.setBackground(Color.WHITE);
this.T=1000;
this.v1 = 8000;
this.v2=7000;
this.x1=200000;
this.y1=6200000;
this.x21=200000;
this.y21=60000000;
JPanel Control=new JPanel();
this.add(Control,BorderLayout.NORTH);
JLabel TIME=new JLabel("时间");
Control.add(TIME);
time=new JTextField("1000");
Control.add(time);
JLabel YV=new JLabel(" 上抛初速度");
Control.add(YV);
yv=new JTextField("8000");
Control.add(yv);
JLabel XV =new JLabel(" 水平方向初速度");
Control.add(XV);
xv=new JTextField("7000");
Control.add(xv);
start = new JButton("启动");
Control.add(start);
start.addActionListener(this);
back= new JButton("复位");
Control.add(back);
back.addActionListener(this);
thread1=new Thread(new Ball1());
thread1=new Thread(new Ball2());
}
public void paint(Graphics g) //绘图
{
super.paint(g);
Baseline(g); //画坐标线 基线
paintUP(g); //上抛运动
paintXP(g); //斜抛
paintXPline((Graphics2D) g); //画斜抛轨迹
this.repaint();
}
private void Baseline(Graphics g)
{
g.setColor(Color.black); //画2条基准线，方便观察
g.drawLine(20, 650, 20, 100);
g.setColor(Color.black);
g.drawLine(20,650, 880, 650);
}
private void paintUP(Graphics g) //画小球上抛运动
{
g.drawOval((int)(x1/Q),(int)(y1/Q), 25, 25);
}
private void paintXP(Graphics g) //画上小球斜抛抛运动
{
g.drawOval((int)(x21/Q),(int)(y21/Q), 25, 25);
}
private List<Line2D> towList = new ArrayList<Line2D>();
private void paintXPline(Graphics2D g) //画斜抛运动的轨迹
{
towList.add(new Line2D.Double(x21/Q+5,y21/Q,x22/Q,y22/Q));//+4加粗效果
g.setPaint(Color.BLUE);
for (Line2D l : towList)
{
g.draw(l);
}
}
class Ball1 implements Runnable //线程1 控制小球上抛
{
int t1=0;
public void run()
{
while (t1<T)
{
t1+=10;
x1 = 30*Q;
y1 = 600*Q-v1 * t1+0.5 * g * t1*t1;
try
{
Thread.sleep(100);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
}
}
}
class Ball2 implements Runnable //线程2 控制小球斜抛
{
int t2=0;
public void run()
{
while (t2<T)
{
t2+=10;
x22 =30*Q+v2 * t2;
y22 =650*Q-v1 * t2+0.5 * g * Math.pow(t2, 2);
x21 = x22;
y21 = y22;
try
{
Thread.sleep(100);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
}
}
}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==start)
{
thread1=new Thread(new Ball1());
thread2=new Thread(new Ball2());
thread1.start();
thread2.start();
T=Integer.parseInt(time.getText());
v1=Integer.parseInt(yv.getText());
v2=Integer.parseInt(xv.getText());
start.setEnabled(false);
back.setEnabled(true);
}
if(e.getSource()==back)
{
this.repaint();
start.setEnabled(true);
back.setEnabled(false);
}
}
}
public static void main(String args[]) //main函数
{
new BallBall();
}
}
[/code]
