Question

我正在努力使用这段代码，我想点击网格的一个单元格，由JPanel个对象制作，并在该单元格中显示一个带有该单元格索引的标签。我做了一个方法来添加最终变量并返回带有该标签的JPanel。它不起作用。我怎么能这样做？

 public MyTest01(int width, int length) { //constructor

    frame.setLayout(new GridLayout(width, length)); //set layout
    JPanel temp = null;
    JLabel l;

    for (int y = 0; y < length; y++) {
        for (int x = 0; x < width; x++) {
            temp = new JPanel();
            temp.setBorder(new LineBorder(Color.black, 1));
            temp=doStuff(temp,x,y);
            frame.add(temp);
        }
    }

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack(); //sets appropriate size for frame
    frame.setVisible(true); //makes frame visible
}

public static JPanel doStuff( final JPanel temp,final int x, final int y) {

MouseListener mouseListener = new MouseAdapter() {
    @Override
    public void mousePressed(MouseEvent mouseEvent) {
       JLabel  l = new JLabel("("+x+" - "+y+")");
     temp.add(l);

    }
};
return temp;
}

Answer 1

您永远不会将监听器添加到JPanel。

添加组件（revalidate）后，您需要repaint和JPanel JLabel;

MouseListener mouseListener = new MouseAdapter() {
    @Override
    public void mousePressed(MouseEvent mouseEvent) {
        JLabel l = new JLabel("(" + x + " - " + y + ")");
        temp.add(l);
        temp.revalidate();;             <-------- revalidate
        temp.repaint();                 <-------- repaint
    }
};
temp.addMouseListener(mouseListener);   <-------- add listener
return temp;

这是工作代码

import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.LineBorder;

public class MyTest {

    JFrame frame = new JFrame();

    public MyTest(int width, int length) { //constructor

        frame.setLayout(new GridLayout(width, length)); //set layout
        JPanel temp = null;
        JLabel l;

        for (int y = 0; y < length; y++) {
            for (int x = 0; x < width; x++) {
                temp = new JPanel();
                temp.setBorder(new LineBorder(Color.black, 1));
                temp = doStuff(temp, x, y);
                frame.add(temp);
            }
        }

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack(); //sets appropriate size for frame
        frame.setVisible(true); //makes frame visible
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            public void run() {
                new MyTest(3, 3);
            }
        });
    }

    public static JPanel doStuff(final JPanel temp, final int x, final int y) {

        MouseListener mouseListener = new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent mouseEvent) {
                JLabel l = new JLabel("(" + x + " - " + y + ")");
                temp.add(l);
                temp.revalidate();;
                temp.repaint();
            }
        };
        temp.addMouseListener(mouseListener);
        return temp;
    }
}

将最终变量传递给MouseListener方法并返回结果

1 个答案: