java - MouseEvent问题 AWT Java

Question

我只是想尝试在与鼠标单击相同的位置绘制一个圆圈，但我无法让它工作。这是代码:

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


public class LineApp
{
    public static void main ( String args[])
    {
        MainWindow mainWdw = new MainWindow();
    }
}

class MainWindow extends Frame
{
    private Point recPoint;
    private boolean mouseClick;


    MainWindow()
    {
        mouseClick = false;
        setBackground( Color.BLACK );
        setSize( 400,300 );
        setLocation( new Point( 300,300));

        addComponentListener(new ComponentCatcher());
        addWindowListener(new WindowCatcher());
        addMouseListener(new MouseCatcher());

        setVisible( true );
    }

    public void paint( Graphics gc )
    {
        gc.setColor(Color.ORANGE);
        if(mouseClick)
        {
            gc.setColor(Color.ORANGE);
            gc.fillOval(recPoint.x, recPoint.y, 30,30);
        }

    }

    class WindowCatcher extends WindowAdapter
    {
        public void windowClosing( WindowEvent evt)
        {
            evt.getWindow().dispose();
            System.exit (0);
        }
    }

    class ComponentCatcher extends ComponentAdapter
    {
        public void componentResized (ComponentEvent evt)
        {
            repaint();
        }
    }

    class MouseCatcher extends MouseAdapter
    {
        public void mousedPressed ( MouseEvent evt)
        {
           Point mousePt = new Point();
           mousePt = evt.getPoint();
           recPoint = new Point(mousePt.x,mousePt.y);
           mouseClick = true;
           repaint();
        }
}

Answer 1

MouseAdapter 中的方法称为 mousePressed ，而不是 mousedPressed。

@Override -annotation 可以帮助您避免这样的错误。如果你会用

  @Override
  public void mousedPressed ( MouseEvent evt)
  {
      ...

你的代码不会被编译。