java - MouseAdapter方法-为什么包括 `mouseDragged`， `mouseMoved`和 `mouseWheelMoved`？

我的目标是简化此代码(一切正常):

package test;

import java.awt.Window;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.JWindow;

public class A extends JWindow implements MouseListener, MouseMotionListener {

    public A() {
        addMouseListener(A.this);
        addMouseMotionListener(A.this);
    }

    @Override
    public void mouseClicked(MouseEvent e) {
    }

    @Override
    public void mousePressed(MouseEvent e) {
        //This method is being used, working fine
    }

    @Override
    public void mouseReleased(MouseEvent e) {
    }

    @Override
    public void mouseEntered(MouseEvent e) {
    }

    @Override
    public void mouseExited(MouseEvent e) {
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        //This method is being used, working fine
    }

    @Override
    public void mouseMoved(MouseEvent e) {
    }
}

但是，如果我决定像这样使用MouseAdapter:

addMouseListener(new MouseAdapter() {
    @Override
    public void mousePressed(MouseEvent e) {
        transferFocusBackward();
        //This method is being used, working fine
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        //This method is being used, not working anymore
    }
});

mouseDragged没有收到任何事件。但是，如果我这样添加MouseMotionListener:

addMouseListener(new MouseAdapter() {
    @Override
    public void mousePressed(MouseEvent e) {
        //This method is being used, working fine
    }
});

addMouseMotionListener(new MouseMotionAdapter() {
    @Override
    public void mouseDragged(MouseEvent e) {
        //This method is being used, working fine
    }
});

然后，一切恢复正常。所以我的问题是-如果mouseDragged类中的mouseMoved，mouseWheelMoved和MouseAdapter方法不起作用，它们的目的是什么？

最佳答案

好的，我想我现在已经明白了:在MouseAdapter类文档中，它说“使用扩展类创建一个监听器对象，然后使用该组件的addMouseListener，addMouseMotionListener和addMouseWheelListener方法在一个组件中注册它”。所以现在看起来像:

private class MouseListeners extends MouseAdapter {

    @Override
    public void mousePressed(MouseEvent e) {
        //This method is being used, working fine
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        //This method is being used, working fine
    }
}

然后:

MouseListeners listeners = new MouseListeners();
addMouseListener(listeners);
addMouseMotionListener(listeners);

现在一切正常。