将MouseListener或MouseMotionListener添加到我的JLabel中，该JLabel位于类似棋盘

Question

我真的不知道该怎么办。我首先创建了一个新的类，它实现了MouseMotionListener和MouseListener，并接受了它的构造函数JLabel:

import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.JLabel;
public class motion implements MouseMotionListener, MouseListener {
motion(JLabel im) {
label1 = im;
}
@Override
public void mousePressed(MouseEvent e) {
if (e.getSource() == label1) {
drag = true;
} 
} 
@Override
public void mouseReleased(MouseEvent e) {
drag = false;
}
@Override
public void mouseDragged(MouseEvent e) {
if (drag == true) {
mouseX = e.getX();
mouseY = e.getY();
label1.setBounds(mouseX, mouseY, 
label1.getWidth(), label1.getHeight());
}
}
public void mouseMoved(MouseEvent e) {}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
public void mouseClicked(MouseEvent e) {}  
private JLabel label1;
private int mouseX;
private int mouseY;
private boolean drag = false;
}

这是我董事会的代码。目前碎片无法移动。我在每个if语句中都有一行添加MouseMotionListener——picLabel.addMouseMotionListener(new motion(picLabel))——但这并没有奏效。

import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
public class Checkerboard {
public static void main (String args[]) throws IOException {
JFrame checkerBoard = new JFrame();
checkerBoard.setSize(700,700);
checkerBoard.setTitle("Lines of Action");
checkerBoard.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
int row = 8;
int col = 8;
Container pane = checkerBoard.getContentPane();
pane.setLayout(new GridLayout(row,col));
Color checker;   
for (int x = 1; x <= (row * col); x++) {
int altr = 0;
altr = (x-1) % col;
altr += (x-1) / col;
if (altr % 2 == 0) {
checker = Color.darkGray;
} else {
checker = Color.lightGray;
}
JPanel panel = new JPanel();
panel.setPreferredSize(new Dimension(400/row, 400/col));
panel.setBackground(checker);
if ((x < 8 && x > 1) || (x < 64 && x > 57)) {
BufferedImage myPicture = 
ImageIO.read(new  File("C:\Users\srjames90\Downloads\BlackPiece.png"));
JLabel picLabel = new JLabel(new ImageIcon( myPicture ));
picLabel.addMouseMotionListener(new motion(picLabel));
panel.add(picLabel);
} else if(check(x)) {
BufferedImage myPicture = 
ImageIO.read(new File("C:\Users\srjames90\Downloads\WhitePiece.png"));
JLabel picLabel = new JLabel(new ImageIcon( myPicture ));
panel.add(picLabel);
}
pane.add(panel);
}
checkerBoard.setVisible(true);
}
static boolean check(int y) {
return y == 9 || y == 16 || y == 17 || y == 24 || y == 25
|| y == 32 || y == 33 || y == 40 || y == 41 || y == 48
|| y == 49 || y == 56;
}
}

Answer 1

要修复此问题，请将侦听器添加到Motion类JLabel

Motion(JLabel im) {
label1 = im;
label1.addMouseListener(this);
}

还请阅读Java编程风格指南

Answer 2

MouseListener和MouseMotionListener定义了两组不同的事件。为了让你的听众同时获得这两个集合，你必须同时注册。。。使用类似的东西：

Motion m = new Motion(picLabel);
picLabel.addMouseMotionListener(m); //will cause m to get mouseMoved and mouseDragged calls
picLabel.addMouseListener(m); //will cause m to get mousePressed, mouseReleased, mouseEntered, mouseExited, etc.

同样值得注意的是，在您发布的代码片段中，您根本没有向WhitePiece.png片段添加任何侦听器。