Java 删除并稍后添加回 MouseListener

Question

我有 4 JLabel s。

首次点击时:

我将背景颜色更改为红色并删除了 JLabel的MouseListener我点击过的。

第二次点击时:

我将背景颜色更改为绿色，但是JLabel我之前单击的不应从红色变为绿色，因为我已经删除了 MouseListener .

第三次点击时:

我想添加回MouseListener到JLabel MouseListener第一次单击时已删除并将背景颜色更改为黑色，但我不知道如何添加回来。

我尝试使用addMouseListener我的方法addbackMouseListener(JLabel label)但似乎我无法在参数中传入“this”，并且我不知道 addMouseListener 的参数要传入什么.

public void addbackMouseListener(JLabel label) {
    label.addMouseListener(this); <-- can't pass in this, what can I do?
}

<小时/>

代码:

import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;


@SuppressWarnings("serial")
public class rMouseListener extends JFrame {
    private JLabel[] jLabel = {new JLabel(), new JLabel(), new JLabel(), new JLabel()};;
    private JPanel panel = new JPanel(new FlowLayout());
    private int clickCount = 0;
    private boolean mouseRemoved = false;

    public rMouseListener() {

        for(int i = 0; i< 4; i++) {
            jLabel[i].setText(i + " ");
            panel.add(jLabel[i]);
            jLabel[i].addMouseListener(new MouseAdapter() {
                @Override
                public void mousePressed(MouseEvent e) {
                    JLabel label =(JLabel) e.getSource();
                    clickCount++;

                    /*remove the mouseListener for the label that is clicked*/
                    if(clickCount == 1) {
                        label.setBackground(Color.red);
                        label.setOpaque(true);
                        label.removeMouseListener(this);
                        mouseRemoved = true;
                    }

                    /* to verify that the mouseListener for that label is removed after
                    first click.*/
                    else if(clickCount == 2) {
                        label.setBackground(Color.green);
                        label.setOpaque(true);
                    }

                    /*check if the mouseListener is removed.
                      add back the mouseListener to the one that is perviously
                      removed at clickCount = 1 if it's removed*/
                    else if(clickCount == 3) {
                        if(mouseRemoved) {
                            addbackMouseListener(label);
                            label.setBackground(Color.black);
                        }
                    }


                }
            });
        }
        add(panel);
        setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        pack();
        setSize(400,600);  
        setLocationRelativeTo(null);
        setVisible(true);
    }

    public void addbackMouseListener(JLabel label) {
        label.addMouseListener(this); <-- can't pass in this, what can I do?
    }

    public static void main(String[] args) {    
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new rMouseListener();
            }
        });
    }
}

Answer 1

this 引用 rMouseListener，它扩展了 JFrame，但它没有实现 MouseListener

您最好的选择可能是让您的原始 MouseAdapter 成为一个内部类，并在创建类时创建它的实例，然后只需添加和删除它即可

例如...

public class rMouseListener extends JFrame {
    //...
    private MouseListener mouseListener;

    public rMouseListener() {

        mouseListener = new MouseHandler();
        for(int i = 0; i< 4; i++) {
            jLabel[i].setText(i + " ");
            panel.add(jLabel[i]);
            jLabel[i].addMouseListener(mouseListener);
        }
        //...
    }

    public void addbackMouseListener(JLabel label) {
        label.addMouseListener(mouseListener); 
    }

    //...

    public MouseHandler extends MouseAdapter {
        @Override
        public void mousePressed(MouseEvent e) {
            JLabel label =(JLabel) e.getSource();
            clickCount++;

            /*remove the mouseListener for the label that is clicked*/
            if(clickCount == 1) {
                label.setBackground(Color.red);
                label.setOpaque(true);
                label.removeMouseListener(this);
                mouseRemoved = true;
            }

            /* to verify that the mouseListener for that label is removed after
            first click.*/
            else if(clickCount == 2) {
                label.setBackground(Color.green);
                label.setOpaque(true);
            }

            /*check if the mouseListener is removed.
              add back the mouseListener to the one that is perviously
              removed at clickCount = 1 if it's removed*/
            else if(clickCount == 3) {
                if(mouseRemoved) {
                    addbackMouseListener(label);
                    label.setBackground(Color.black);
                }
            }


        }
    }
}