java疑惑

[Android-]

我写的一个小代码想实现小球沿着frame的对角线来回碰撞，可运行情况并非如此，求解。。

import java.awt.*;
import java.awt.event.*;
import java.awt.Graphics;

public class Ex4_2_1 extends Frame
implements Runnable
{

int x=0,y=0,dx=5,dy=5;

public static void main(String args[])
{
new Ex4_2_1();

}

public Ex4_2_1()
{

setSize(640,640);
setVisible(true);
new Thread(this).start();

}

public void run()
{
while(true){

x=x+dx;
y=y+dy;
repaint();
if(x<=0)
dx=5;
else if((x+80)>=getWidth()) dx=-5;

if(y<=50)
dy=5;
else if ((y+80)>=getHeight()) dy=-5;
try{Thread.sleep(250);}
catch(InterruptedException e)
{
;
}
}
}

public void paint(Graphics g)
{
g.setColor(Color.red);
g.fillOval(x,y,80,80);

}
}

[风尘中国]

你改一下程序当中具体的参数，就是因为这个参数导致的无法来会碰撞

还有需要隐藏标题栏，这样碰撞看的才完整，以下是我执行的代码

package csdn.p41;

import java.awt.*;
import java.awt.event.*;
import java.awt.Graphics;

public class Ex4_2_1 extends Frame
        implements Runnable
{

    int x=0,y=0,dx=5,dy=5;

    public static void main(String args[])
    {
        new Ex4_2_1();

    }
    @Override
    public   Insets   getInsets()
    {
        return   new   Insets(1,   1,   1,   1);
    }

    public Ex4_2_1()
    {
        this.setUndecorated(true);  //去掉边框 
        setSize(640,640);
        setVisible(true);
        new Thread(this).start();
        this.addWindowListener(new WindowAdapter(){

            @Override
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });

    }

    public void run()
    {
        while(true){

            x=x+dx;
            y=y+dy;
            System.out.println("x="+x+",y="+y);
            repaint();
            if(x<=5) //保证跟y的阈值一致
                dx=5;
            else if((x+80)>=getWidth()) dx=-5;

            if(y<=5) //这里调整了一下参数，保证跟x的阈值一致
                dy=5;
            else if ((y+80)>=getHeight()) dy=-5;
            try{
                Thread.sleep(50);
            }catch(InterruptedException e)
            {
                e.printStackTrace();
            }
        }
    }
    @Override
    public void paint(Graphics g)
    {
        super.paint(g);
        g.setColor(Color.red);
        g.fillOval(x,y,80,80);

    }
}

[Android-]

谢谢，问题解决啦。