Question

我正在尝试在JFrame中不断创建一个围绕鼠标的圆圈，即圆圈跟随屏幕上的鼠标。为此，我尝试使用repaint（）和一个计时器，以便圆圈不断更新其位置。现在，我让程序每秒重新绘制一次圆圈。

class MouseJFrame  extends JFrame implements MouseListener{
    int circleXcenter;
    int circleYcenter;
    int circleRadius = 25;
    boolean show = false;
    int delay = 1000; 

// listen for and respond to mouse events
    public MouseJFrame(){
        new Timer(delay, taskPerformer).start();
        addMouseListener(this);
    }

// paints a circle
    public void paint(Graphics g){
        super.paint(g);
        if(show){
          g.drawOval(circleXcenter,circleYcenter,
                            circleRadius*2,circleRadius*2);
        }
    }

// getX and getY return the location of the mouse
    ActionListener taskPerformer = new ActionListener() {
    public void mouseDragged(MouseEvent e){
      int xLocation = e.getX();
      int yLocation = e.getY();
      show = true;
      circleXcenter = xLocation-circleRadius;
      circleYcenter = yLocation-circleRadius;
      repaint();
   }

    public void mouseMoved(MouseEvent e){
      int xLocation = e.getX();
      int yLocation = e.getY();
      show = true;
      circleXcenter = xLocation-circleRadius;
      circleYcenter = yLocation-circleRadius;
      repaint();
    }
    };                                                


// class to create MouseJFrame object
public class TestMouseJFrame{

    public static void main(String[] a){
       MouseJFrame  myMouseJFrame = new MouseJFrame ();
       myMouseJFrame.setSize(200, 200);
       myMouseJFrame.setVisible(true);
    }
}

但是，我收到有关ActionListener的错误消息。当我尝试修复此问题时，我会遇到其他错误。我该怎么做才能让我的程序按预期运行？

Java的; Jframe没有重新粉刷

0 个答案: