java - JLabel 在 ActionListener 中没有被正确识别

Question

我问这个是最后的手段，因为我找不到任何关于我在这个随机数游戏中遇到的问题的帮助。

问题是，当我尝试运行该程序时，ActionListener 中出现错误，提示“无法解析 guessResult”。

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

public class Project8 extends JFrame
{
private JTextField numGuessFld;
private JButton guessBtn, guessAgainBtn, playAgainBtn;
private int randNum;
private Container c = getContentPane();
private int numGuessed;
private Random rn = new Random();



public static void main(String[] args) 
{
    Project8 frm = new Project8();
    frm.setSize(400,150);
    frm.setVisible(true);
    frm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);     
}//end main

public Project8()
{
    c.setLayout(new FlowLayout());
    setTitle("Number Guessing Game");

    JLabel gameDescriptLbl = new JLabel("I have a number between 1 and 1000.  Can you guess my number?");
    c.add(gameDescriptLbl);

    JLabel numGuessLbl = new JLabel("Please enter your first guess. ");
    c.add(numGuessLbl);

    numGuessFld = new JTextField(4);
    c.add(numGuessFld);

    guessBtn = new JButton("Guess");
    c.add(guessBtn);

    guessAgainBtn = new JButton("Guess Again");
    guessAgainBtn.setEnabled(false);
    c.add(guessAgainBtn);

    playAgainBtn = new JButton("Play Again?");
    playAgainBtn.setEnabled(false);
    c.add(playAgainBtn);

    JLabel guessResult = new JLabel("");
    c.add(guessResult);

    Handler handler = new Handler();

    numGuessFld.addActionListener(handler);
    guessBtn.addActionListener(handler);
    guessAgainBtn.addActionListener(handler);
    playAgainBtn.addActionListener(handler);

    randNum = rn.nextInt(1000)+1;
}//end constructor Project8

private class Handler implements ActionListener
{       
    public void actionPerformed(ActionEvent e)
    {           
        if (e.getSource() == guessBtn)
        {               
            String input = numGuessFld.getText();
            numGuessed = Integer.parseInt(input);
            System.out.println(numGuessed);
            System.out.println(randNum);                

            if (numGuessed < randNum)
            {
                c.setBackground(Color.blue);                    
                guessResult.setText("Too low!");
                guessAgainBtn.setEnabled(true);                     
            }
            else if (numGuessed > randNum)
            {
                c.setBackground(Color.red);
                guessResult.setText("Too high!");                   
                guessAgainBtn.setEnabled(true);                 
            }
            else if (numGuessed == randNum)
            {
                c.setBackground(Color.yellow);
                guessResult.setText("Correct!");                    
                guessAgainBtn.setEnabled(false);
                guessBtn.setEnabled(false);
                numGuessFld.setBackground(Color.green);
                numGuessFld.setEditable(false);
                playAgainBtn.setEnabled(true);                  
            }   

        }//end guessBtn if          

        if (e.getSource() == guessAgainBtn)
        {
            numGuessFld.setText("");

        }//end guessAgainBtn if

        if (e.getSource() == playAgainBtn)
        {
            c.setBackground(null);
            numGuessFld.setText("");                
            guessAgainBtn.setEnabled(false);
            guessBtn.setEnabled(true);
            numGuessFld.setBackground(null);
            numGuessFld.setEditable(true);
            playAgainBtn.setEnabled(false); 
            randNum = rn.nextInt(1000)+1;
        }//end playAgainBtn if          
    }//end ActionPerformed
}//end Handler
}//end Project8

任何帮助将不胜感激......特别是如果它在 4:30 之前到达:) 谢谢!

Answer 1

您遇到范围界定问题。尝试将 guessResult 设为成员变量，而不是局部变量。