Java新GUI问题[已关闭]

Question

不久前我在这里发了一个问题。我对它有不同的问题。我已经改变了我的代码，就图形处理而言，但它仍然不能正常工作。

它绘制的底部框架非常好（一个与按钮等）然而。在此之上，刽子手游戏本身应该是平局。才不是。它根本没有画任何东西。我不知道该怎么办。我要疯了，因为这是我今晚到期的最后一个项目！谁能帮帮我吗？

下面是我的代码：（我尽可能地省略了更多的代码，但是如果您需要整个程序来测试自己，请在这里找到它。）

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

import java.util.Random;

public class Hangman extends JFrame {

    private Hangman.Hangman_Panel canvas = new Hangman.Hangman_Panel();

    // How many times you can guess the wrong letter till you lose
    static final int DEAD = 7;   

    private int errors;        // amount of errors
    private String message;   // Message displaying either Error or Victory
    private String information; // Secondary Message
    private String RealWord;      // The Real word
    private StringBuffer GuessWord;// The Guessed word
    private Button StartBtn;      // The Restart Button
    private Button GoBtn;         // The Go Button
    private TextField LetterBox; // The LetterBox

    //Contructor
    public Hangman() { 

        this.add(canvas, BorderLayout.CENTER); // Add canvas to center  
        // Create a "Textbox" for the letter guessing
        LetterBox = new TextField();

        JPanel p = new JPanel();
        p.setLayout(new FlowLayout());

        p.add(StartBtn = new Button("Restart"));
        p.add(new Label("Guess a letter"));
        p.add(LetterBox);
        p.add(GoBtn = new Button("Go"));

        add(p, BorderLayout.SOUTH);

    }

    public static void main(String[] args) {

        JFrame frame = new Hangman();

        frame.setSize(300, 400);
        frame.setLocationRelativeTo(null); // Center the frame
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);

    }

    class Hangman_Panel extends JPanel implements ActionListener {

        @Override
        public void paint(Graphics g) {
            super.paintComponent(g);

            int BaseY = 250;

            //THE HANGING STAND
            if (errors > 0) { //1 Error
                g.drawLine(90, BaseY, 200, BaseY); //The ground
                g.drawLine(125, BaseY, 125, BaseY-100); //The bar going up
                g.drawLine(125, BaseY-100, 175, BaseY-100); //The sidebar
                g.drawLine(175, BaseY-100, 175, BaseY-75); //The Rope
            }

            //THE PERSON
            if (errors > 1) { 
               g.drawOval(170, BaseY-75, 10, 12); // The Head       
            }

            if (errors > 2) { 
               g.drawLine(175, BaseY-62, 175, BaseY-45); // The Body    
            }

            if (errors > 3) { 
               g.drawLine(165, BaseY-65, 175, BaseY-55); // Left Arm  
            }

            if (errors > 4) { 
               g.drawLine(185, BaseY-65, 175, BaseY-55); // Right Arm 
            }

            if (errors > 5) { 
               g.drawLine(170, BaseY-30, 175, BaseY-45); //Left Leg       
            }

            if (errors > 6) {  //7 Errors
               g.drawLine(175, BaseY-45, 180, BaseY-30); // Right Left 
            }

            //Show Messages/Errors
            g.drawString(message, 40, BaseY+25);
            g.drawString(information, 25, BaseY+45);
            g.drawString(new String (GuessWord), 140, BaseY-120);

            g.drawString(new String("WELCOME TO HANGMAN!"), 75, 40);
        }

        public void init() {

            //Make buttons event listeners
            StartBtn.addActionListener(this);
            GoBtn.addActionListener(this);

            //Startup the Game
            initGame();

        }

}

private Hangman.Hangman_Panel canvas = new Hangman.Hangman_Panel();

//Constructor
public Hangman() { 

    this.add(canvas, BorderLayout.CENTER); // Add canvas to center  

Answer 1

快速尝试您的代码会出现一个明显的异常，您忘记在paint方法上检查字符串是否为null

g.drawString(message, 40, BaseY+25);
g.drawString(information, 25, BaseY+45);
g.drawString(new String (GuessWord), 140, BaseY-120);

我知道您的作业很快就要完成了，但我强烈建议您学习如何读取异常堆栈跟踪、使用IDE和调试代码。把它看作是对你未来编程生涯的一种投资。