MouseMotion监听器不工作

Question

我正在编写一段代码来添加和定义mousemotion监听器，但编译器将错误报告给以下代码：“class CustomListener是公共的，应在名为CustomListener.java的文件中声明 公共类CustomListener实现MouseMotionListener { ^ 1错误 “ 我不知道这是什么意思。

import javax.swing.*; 
import java.awt.*; 
import java.awt.event.*; 


public class TetrisGUI implements ActionListener{ 

JButton quit = new JButton(); 
JLabel label1 = new JLabel(); 
JLabel label2 = new JLabel(); 
JLabel label3 = new JLabel(); 
JPanel mainArea = new JPanel(); 

public static void main(String[] args) { 

    TetrisGUI gui = new TetrisGUI(); 
    gui.go(); 
} 

public void go() { 
    JFrame frame = new JFrame(); 
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    quit = new JButton("QUIT"); 
    label1 = new JLabel("Level:  1"); 
    label2 = new JLabel("Lines:  0"); 
    label3 = new JLabel("Score:  0"); 

    quit.addActionListener(this); 
    mainArea.addMouseMotionListener(new CustomListener(){}); 

    MyDrawPanel drawPanel = new MyDrawPanel(); 

    frame.getContentPane().add(quit); 
    frame.getContentPane().add(label1); 
    frame.getContentPane().add(label2); 
    frame.getContentPane().add(label3); 
    frame.getContentPane().add(mainArea); 
    frame.getContentPane().add(BorderLayout.CENTER,drawPanel); 

    label1.setSize(100,200); 
    label1.setLocation(310,60); 
    label2.setSize(100,200); 
    label2.setLocation(310,110); 
    label3.setSize(100,200); 
    label3.setLocation(310,160); 
    mainArea.setSize(250,500); 
    mainArea.setLocation(20,50); 
    quit.setSize(100,40); 
    quit.setLocation(300,310); 
    frame.setSize(400,500); 
    frame.setVisible(true); 
    mainArea.setBackground(new Color(0,0,0,0)); 
    mainArea.setVisible(true); 
} 

public void actionPerformed(ActionEvent event) { 
    System.exit(0); 
} 


} 

class MyDrawPanel extends JPanel { 
public void paintComponent(Graphics g) { 
    g.setColor(Color.black); 
    g.drawRect(20,50,250,500);//Main Area 
    g.drawRect(300,50,100,70);//NextShape 

    g.drawRect(145,80,25,25);//Tian Block 
    g.drawRect(145,105,25,25); 
    g.drawRect(120,80,25,25); 
    g.drawRect(120,105,25,25); 
    Color deepGreen = new Color(51,138,52); 
    g.setColor(deepGreen); 
    g.fillRect(121,81,24,24);//Tian Block 
    g.fillRect(121,106,24,24); 
    g.fillRect(146,81,24,24); 
    g.fillRect(146,106,24,24); 

    g.setColor(Color.black); 
    g.drawRect(245,525,25,25);//Right bottom 
    g.drawRect(220,525,25,25); 
    g.drawRect(195,525,25,25); 
    g.drawRect(170,525,25,25); 
    g.drawRect(245,500,25,25); 
    g.drawRect(245,475,25,25); 
    g.drawRect(220,500,25,25); 
    g.drawRect(195,500,25,25); 
    Color deepBlue = new Color(15,66,148); 
    g.setColor(deepBlue); 
    g.fillRect(246,526,24,24); 
    g.fillRect(221,526,24,24); 
    g.fillRect(246,501,24,24); 
    g.fillRect(246,476,24,24); 
    Color brightYellow = new Color(252,238,33); 
    g.setColor(brightYellow); 
    g.fillRect(196,526,24,24); 
    g.fillRect(171,526,24,24); 
    g.fillRect(196,501,24,24); 
    g.fillRect(221,501,24,24); 

    //NextShape Blocks 
    g.setColor(Color.black); 
    g.drawRect(360,60,25,25); 
    g.drawRect(335,85,25,25); 
    g.drawRect(360,85,25,25); 
    g.drawRect(310,85,25,25); 
    Color deepRed = new Color(227,23,36); 
    g.setColor(deepRed); 
    g.fillRect(361,61,24,24); 
    g.fillRect(336,86,24,24); 
    g.fillRect(361,86,24,24); 
    g.fillRect(311,86,24,24); 
} 
} 

public class CustomListener implements MouseMotionListener { 
public void mousePressed(MouseEvent me){} 
public void mouseReleased(MouseEvent me){} 
public void mouseClicked(MouseEvent me){} 
public void mouseEntered(MouseEvent me){ 

} 
public void mouseExited(MouseEvent me){} 
} 

Answer 1

在java中，每个公共类都必须在单独的文件中定义。将类'CustomListener'移动到具有相同名称的其他文件，或者删除公共修饰符。