java - 将最终变量传递给 MouseListener 方法并返回结果

Question

我正在努力处理这段代码，我想单击由 JPanel 对象创建的网格单元格之一，并在该单元格中显示一个带有该单元格索引的标签。我创建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。我怎样才能做到这一点？

 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

1. 您永远不会将监听器添加到 JPanel。

2. 添加组件 (JLabel) 后，您需要重新验证并重新绘制JPanel；

   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;
   

<小时/>

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;
    }
}