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嗨，我无法接受用户输入并使其接收用户输入。然后获取用户输入并使用它来创建一个新的文本空白文本文件。我可以让它工作，但是当我使用 JTextField 时它不会创建文件。

任何帮助将不胜感激。

这是我的代码：

import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JOptionPane;
import javax.swing.*;
import java.io.*;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JTextArea;
import java.util.Scanner;

public class newGame extends JFrame {
    private JButton reg;
    private JTextField userName;
    private JTextField info;
    Scanner input = new Scanner(System.in);

    public newGame() {

        super ("Rock Paper Scissors");

        //creates the text fields
        info = new JTextField ("Welcome to the rock, Please enter your username below");
        info.setEditable(false);
        JTextField userName = new JTextField ("name");

        //impliments actionlistner
        newClass saver = new newClass();
        userName.addActionListener(saver);


        //adds the fields to the Content Layout
        JPanel content = new JPanel();
        content.setLayout(new BorderLayout());
        content.add(info, BorderLayout.NORTH);
        content.add(userName, BorderLayout.SOUTH);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setContentPane(content);
        setTitle("Rock Paper Scissors The Game");
        pack();


    }


    private class newClass implements ActionListener {
        public void actionPerformed (ActionEvent event) {

            String newUserName = userName.getText();
            File file = new File(newUserName + ".txt");
            boolean blnCreated = false;
            try {
                blnCreated = file.createNewFile();
            } catch(IOException ioe) {
            }
            JOptionPane.showMessageDialog
                (null,String.format("%s",event.getActionCommand()));
        }
    }
}
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1 回答 1

2

您正在隐藏变量userName，因此永远不会设置同名的类成员变量，从而导致在NPE创建ActionListener文件之前。代替

JTextField userName = new JTextField("name");

和

userName = new JTextField("name");
于 2013-05-28T18:43:31.873 回答