我希望的是，将小球和枪放在同一个面板中，小球的位置是随机出现在框架中的。此时，要得到框架的高度和宽度，要在paintComponent方法中用getWidth啊。。但如果这样，当我移动枪时，小球的位置又发生了变化。。。
现我把程序改成下面这样，但小球的位置就一直是0,0了。。。
谁知道怎么改啊？？？
谢谢了

如果用一个面板来装这两个，如下
        gun.setFocusable(true);
        
        p1.add(gun);
        p1.add(ball);
        
        add(p1);

那么枪的位置就不在最下面了。还是错的。。。
[attach]73718[/attach]


 
import java.awt.*;
 
import javax.swing.*;
 
import java.awt.event.*;
 
 
public class BallGame extends JFrame {
   
    private Ball ball = new Ball();
    Ball.Gun gun = ball.new Gun();
   
    public BallGame(){
        
    //    add(ball);
        add(gun);
        gun.setFocusable(true);
        
   
    }
   
    public static void main (String[] args){
        BallGame frame = new BallGame();
        frame.setTitle("BallGame");
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(200,200);
        frame.setVisible(true);
    }
   
    public class Ball extends JPanel {
        
        int xCoordinate ;
        int yCoordinate ;
   
        protected void paintComponent(Graphics g){
            super.paintComponent(g);
            
            xCoordinate = (int)(Math.random() * getWidth());
            yCoordinate = (int)(Math.random() * getHeight());
                    
            g.drawOval(xCoordinate, yCoordinate, 10, 10);
            
            }
    //    }
   
   
        
    public class Gun extends JPanel {
        
        private int x1 = 0;
        private int x2 = 0;
        private int y1 = 0;
        private int y2 = 0;
        private int arc = 0;
        private int xBall = 0;
        private int yBall = 0;
        
        public Gun(){
            
            xBall = xCoordinate;
            yBall = yCoordinate;
            this.x1 = x1;
            this.x2 = x2;
            this.y1 = y1;
            this.y2 = y2;
            
            addKeyListener(new KeyAdapter(){
                public void keyPressed(KeyEvent e){
                    switch(e.getKeyCode()){
                    case KeyEvent.VK_LEFT: if(arc > 90)
                                                arc -= 90;
                                            else if (arc < 0)
                                                arc += 90;
                                            else
                                                arc++; break;
                    case KeyEvent.VK_RIGHT: if(arc > 90)
                                                arc -= 90;
                                            else if (arc < 0)
                                                arc += 90;
                                            else
                                                arc--; break;
                    default: arc = getArc();
                    }
                repaint();
                }
            });
        }
        
        public int getArc(){
            return arc;
        }
        
        protected void paintComponent(Graphics g){
            super.paintComponent(g);
            
            
            x1 = getWidth() / 2;
            y1 = getHeight();        
            x2 = getWidth() / 2 + (int)((Math.cos(arc * (2 * Math.PI / 180))) * 50);
            y2 = getHeight() - (int)((Math.sin(arc * (2 * Math.PI / 180))) * 50);
            
            g.drawLine(x1, y1, x2, y2);
            g.drawOval(xBall, yBall, 10, 10);
   
        }
    }
    }
}

[ 本帖最后由 ilvhmfer 于 2013-11-24 08:38 编辑 ]

如果用一个面板来装这两个，如下
gun.setFocusable(true);
        
        p1.add(gun);
        p1.add(ball);
        
        add(p1);

那么枪的位置就不在最下面了。还是错的。。。