Java Hangman程序中JOptionPane / JPanel的奇怪问题

Question

关于我的Hangman程序，我有一个非常具体的问题。

您可能希望自己运行该程序以了解我遇到的问题。

当计数器（保持错误猜测数量的变量）达到6时出现问题。此时，用户已经用完所有分配的猜测，并可以选择再次播放。如果用户选择再次播放，则调用askQuestion方法，其中JOptionPane从用户获取将成为要猜测的新单词的String。

用户输入单词并单击“确定”后，JOptionPane由于某种原因被绘制到Panel上。

这是我遇到的问题。它在您提交一封信作为猜测后消失，但在它存在时是一个非常难看的错误。我上面有一个截图。这是我的代码：

//********************************************************
//  HangmanPanel.java        
//
//  Creates your run-of-the mill hangman game.
//********************************************************

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

public class HangmanPanel extends JPanel
{

private JLabel inputLabel;    // Input field for letter guesses
private String word;          // Variable to hold answer word 
private String guessed = "Guessed: ";  // Holds letters already guessed
private String l, text = "";  // l: Variable to hold letter guess; text: Tells user whether their guess was correct
private JTextField letter;    // Text Field for Input Label
private int counter = 0;      // Incremented when wrong guess is made; controls drawing of hangman
private String underscore = "";    // Shows answer as sequence of underscores, which are replaced with correct guesses
private boolean playing = true;

//------------------------------------------
//  Sets up the hangman panel.
//------------------------------------------
public HangmanPanel()
{
    setBackground (Color.white);
    setPreferredSize (new Dimension(300, 300));
    askQuestion();

    inputLabel = new JLabel ("Enter a letter.");
    add (inputLabel);


    letter = new JTextField (1); 
    add (letter);
    letter.addActionListener(new TempListener());
}
public void askQuestion()
{
    word = JOptionPane.showInputDialog ("Enter the word.");
    for (int i = 0; i < word.length(); i++)
    {
        underscore += "-";    
    }

    repaint();
}
//----------------------------------
//  Paints a hanging man.
//----------------------------------
public void paintComponent (java.awt.Graphics page)
{

    super.paintComponent (page);

    final int xBound = 200, yBound = 20;

    if (playing)
    {
        page.setColor (Color.black);

        page.fillRect(xBound + 30, yBound + 80, 60, 10); // Stand
        page.fillRect (xBound +55, yBound, 10, 80); // Gallows Pole
        page.fillRect(xBound + 25, yBound, 40, 5);
        page.fillRect(xBound + 25, yBound, 3, 20); // Rope

        if (counter > 0)
        page.fillOval(xBound + 18, yBound + 15, 16, 16); // Head
        if (counter > 1)
        page.fillRect(xBound + 24, yBound + 23, 5, 30); // Torso
        if (counter > 2)
        page.drawLine(xBound + 23, yBound + 40, xBound + 13, yBound + 30); // Right Arm
        if (counter > 3)
        page.drawLine(xBound + 29, yBound + 40, xBound + 39, yBound + 30); // Left Arm
        if (counter > 4)
        page.drawLine(xBound + 23, yBound + 53, xBound + 18, yBound + 63); // Right Leg
        if (counter > 5)
        {
            page.drawLine(xBound + 29, yBound + 53, xBound + 34, yBound + 63); // Left Leg
            text = "";
            counter=0;
            underscore = "";
            guessed = "Guessed: ";

           //page.drawString("Play Again?", 50, 130);
            int again = JOptionPane.showConfirmDialog (null, "Do Another?");
            if (again == JOptionPane.YES_OPTION)
                askQuestion();
            else 
                playing = false;



        }

        page.drawString(guessed, 20, 130);

        page.drawString(underscore, 20, 110);

        page.drawString(text, 20, 250);

    }
    else
        page.drawString("Goodbye", 50, 50);
}

private class TempListener implements ActionListener
{
    public void actionPerformed (ActionEvent event)
    {
        l = letter.getText();     // Stores letter guess as a string
        letter.setText("");       // Clears Text Field
        char let = l.charAt(0);   // Creates a char variable for letter guess
        guessed = guessed + let + " ";

        int index = word.indexOf(let);
        if (index != -1)
        {
            text = "Correct";
            underscore = underscore.substring(0,index) + word.substring(index, index+1) + underscore.substring(index+1); // Replaces underscore with found letter
            String substring = word.substring(index+1);
            int index2 = substring.indexOf(let);

            while (substring.indexOf(let) != -1)
            {
                index2 = substring.indexOf(let);
                index = index + index2 + 1;
                underscore = underscore.substring(0,index) + word.substring(index, index+1) + underscore.substring(index+1);
                substring = word.substring(index+1);
            }
        }
        else
        {
            text = "Wrong";
            counter++;
        }
        if (underscore.indexOf('-') == -1)
        {
            text = "You Win!";
            //askQuestion
        }


        repaint();

    }

}

}

这是HangmanFrame类。这与我的问题无关，我只将其包含在那些想要运行该程序的人中：

import javax.swing.JFrame;

public class HangmanFrame
{
    //----------------------------------------------
    //  Creates the main frame of the program.
    //----------------------------------------------
    public static void main (String[] args)
{
    JFrame frame = new JFrame ("Hangman");
    frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);

    HangmanPanel panel = new HangmanPanel();

    frame.getContentPane().add(panel);
    frame.pack();
    frame.setVisible(true);

}

}

这是我的Search类，它与我的问题没有直接关系：

public class Search{
    public static Comparable linearSearch (String word, String letter, int start)
    {

        while (!found && index < word.length())
        {
            if (word.charAt(index) == letter.charAt(0))
                found = true;
            else
                index++;
        }
        if (found)
            return index;
        else
            return null;

    }
}

我为那里的格式问题道歉，我尽我所能。无论如何我希望有人可以指出我正确的方向，我怀疑问题可以通过调用repaint（）来解决，但我无法这样做。还想提一下，这个程序显然还有很多其他缺陷;它远非强大。那是因为它还远未完成。你不必把这些问题引起我的注意，我会在解决这个问题之后再研究它们。谢谢你看看！ 编辑：我的问题已得到修复，但我仍然希望暂时保持这个问题，看看是否有人能够明确说明我的原始代码无法正常工作的原因。

Answer 1

问题可能与您在JOptionPane.showConfirmDialog方法中显示paintComponent的事实有关。该方法负责组件绘制。避免将程序逻辑放入该方法中。绘画操作应该快速和优化，以获得更好的性能和用户体验。从这种方法弹出模态对话框不是一个好主意。而且，您无法控制何时调用此方法。调用repaint()仅调度组件的更新请求。

查看Performing Custom Painting tutorial了解详情和示例。另请参阅Painting in AWT and Swing。