java - 为什么会收到{错误？

我正在获取Java：105：错误：非法字符：\ 29
}

我正在编写一个程序，用户可以在其中单击右/左/上/下按钮并在屏幕上移动“球”。

我不知道自己在做什么错。有人可以帮我吗？

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

public class Lab2a extends JFrame {

Lab2a(){
    setTitle("Lab 1b - Application #2");
    Lab2Panel p = new Lab2Panel();
    add(p);
}

public static void main(String[] args){

    Lab2 frame = new Lab2();
    frame.setTitle("Lab2 Application # 1");
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(600, 400);
    frame.setVisible(true);
    }

}

class Lab2Panel extends JPanel{
Lab2Button canvas = new Lab2Button();
JPanel panel = new JPanel();

Lab2Panel () {

    setLayout(new BorderLayout());

    JButton leftButton = new JButton("left");
    JButton rightButton = new JButton("right");
    JButton upButton = new JButton("up");
    JButton downButton = new JButton("down");

    panel.add(leftButton);
    panel.add(rightButton);
    panel.add(upButton);
    panel.add(downButton);

    this.add(canvas, BorderLayout.CENTER);
    this.add(panel, BorderLayout.SOUTH);

    leftButton.addActionListener(new LeftListener(canvas));
    rightButton.addActionListener(new RightListener(canvas));
    upButton.addActionListener(new UpListener(canvas));
    downButton.addActionListener(new DownListener(canvas));
}


}

class Lab2Button extends JPanel {
int radius = 5;
int x = -1;
int y = -1;

protected void paintComponent(Graphics g){
    if (x<0 || y<0) {
        x = getWidth() / 2 - radius;
        y = getHeight() / 2 - radius;
    }
    super.paintComponent(g);
    g.drawOval(x,y, 2 * radius, 2 * radius);

}

        public void moveLeft(){

            x -= 5;
            this.repaint();
        }

        public void moveRight(){

            x += 5;
            this.repaint();
        }

        public void moveUp(){
            y += 5;
            this.repaint();
        }

        public void moveDown(){
            y -= 5;
            this.repaint();
        }


}

class LeftListener implements ActionListener{
    private Lab2Button canvas;

    LeftListener(Lab2Button canvas) {
     this.canvas = canvas;
    }

    public void actionPerformed(ActionEvent e){
     canvas.moveLeft();
    }
}

抱歉，该行上方的那行是105。

class RightListener implements ActionListener{
    private Lab2Button canvas;

    RightListener(Lab2Button canvas) {
        this.canvas = canvas;
    }

    public void actionPerformed(ActionEvent e){
      canvas.moveRight();
    }
}


class UpListener implements ActionListener{
    private Lab2Button canvas;

    UpListener(Lab2Button canvas) {
        this.canvas = canvas;
    }

    public void actionPerformed(ActionEvent e){
        canvas.moveUp();
    }
}



class DownListener implements ActionListener{
    private Lab2Button canvas;

    DownListener(Lab2Button canvas) {
        this.canvas = canvas;
    }

    public void actionPerformed(ActionEvent e){
     canvas.moveDown();
    }
}

最佳答案

因此，似乎存在一些问题，但与您所描述的不完全相同。


第15行Lab2 frame = new Lab2();可能应该为Lab2a frame = new Lab2a();，否则您错过了包含Lab2对象的声明的权限。
解决问题1后，代码即可正常编译。这意味着错误位于2个位置之一。


您可能排除的Lab2声明。
源文件的字节，在这种情况下，最好的办法是从另一个源（例如StackOverflow）中删除并重新粘贴代码，或者更好地重新键入代码。您可以沿途改进格式：)