Question

我在Java（GUI）中创建一个程序，当你填写TextFields并单击enter;姓名，年龄，电子邮件，国籍和手机号码将保存在名为 StoredInfo.txt 的文本文件中。我创建的程序没有删除您输入的数据如果你再次填写文本字段。

我想要做的是使用我创建的清除数据按钮，它将删除存储在文本文件中的所有数据（ StoredInfo.txt ）。

这是我的计划：

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

public class SignUp extends JFrame implements ActionListener 
{
    //Variables
    private JButton enter,clear;
    private JLabel header,name,age,email,nationality,cellno;
    private JTextField nameTF,ageTF,emailTF,nationalityTF,cellnoTF;
    private Container container;
    private PrintWriter pwriter;


    //Constructor
    public SignUp()
    {
        setTitle("Form");
        setSize(500,500);
        setResizable(false);
        setDefaultCloseOperation(this.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setLayout(null);

        container = this.getContentPane();
        container.setBackground(Color.GRAY);

        enter = new JButton("Enter");
        clear = new JButton("Clear Data");

        header = new JLabel("Form");
        name = new JLabel("Name: ");
        age = new JLabel("Age: ");
        email = new JLabel("Email Address: ");
        nationality = new JLabel("Nationality: ");
        cellno = new JLabel("Cellphone #: ");

        nameTF = new JTextField(20);
        ageTF = new JTextField(20);
        emailTF = new JTextField(20);
        nationalityTF = new JTextField(20);
        cellnoTF = new JTextField(20);

        nameTF.addActionListener(this);
        ageTF.addActionListener(this); 
        emailTF.addActionListener(this); 
        nationalityTF.addActionListener(this); 
        cellnoTF.addActionListener(this); 
        enter.addActionListener(this);
        clear.addActionListener(this);

        //Add section

        this.add(header);
        this.add(name);
        this.add(age);
        this.add(email);
        this.add(nationality);
        this.add(cellno);

        this.add(header);
        this.add(nameTF);
        this.add(ageTF);
        this.add(emailTF);
        this.add(nationalityTF);
        this.add(cellnoTF);

        this.add(clear);
        this.add(enter);

        //SetBounds
        enter.setBounds(180,270,80,40);
        clear.setBounds(270,270,100,40);

        header.setBounds(230,30,80,50);
        header.setFont(new Font("Arial",Font.BOLD,25));
        header.setForeground(Color.WHITE);

        name.setBounds(80,90,40,40);
        age.setBounds(80,120,40,40);
        email.setBounds(80,150,110,40);
        nationality.setBounds(80,180,100,40);
        cellno.setBounds(80,210,100,40);

        nameTF.setBounds(180,95,190,25);
        ageTF.setBounds(180,125,190,25);
        emailTF.setBounds(180,155,190,25);
        nationalityTF.setBounds(180,185,190,25);
        cellnoTF.setBounds(180,215,190,25);

        name.setForeground(Color.WHITE);
        age.setForeground(Color.WHITE);
        email.setForeground(Color.WHITE);
        nationality.setForeground(Color.WHITE);
        cellno.setForeground(Color.WHITE);


        //Setting Up Text File

        try
        {
            File data = new File("StoredInfo.txt");
            pwriter = new PrintWriter(new FileWriter(data,false));

            if(data.exists())
            {

            }else
            {
                data.createNewFile();
            }

        }catch(Exception e)
        {
            e.printStackTrace();
        }
        setVisible(true);
    }

    //Actions
    public void actionPerformed(ActionEvent e)
    {
        Object action = e.getSource();

        if(action.equals(enter))
        {

            pwriter.println("Name: " + nameTF.getText());
            pwriter.println("Age: " + ageTF.getText());
            pwriter.println("Email: " + emailTF.getText());
            pwriter.println("Nationality: " + nationalityTF.getText());
            pwriter.println("CellNo #: " + cellnoTF.getText());
            pwriter.println("---------------------------");

            pwriter.flush();
            pwriter.close();



        }else if(action.equals(clear))
        {

        }
    }

    ///Main
    public static void main(String args[])
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                new SignUp();
            }

        });

    }
}

Answer 1

一般来说，new FileWriter(file);会覆盖file，将其留空。

在你的情况下，

else if (action.equals(clear)) {

   // Need to close this first to avoid resource leak
   pw.close(); 

   File data = new File("StoredInfo.txt");

   // I believe you will need pw later
   pw = new PrintWriter(new FileWriter(data, false));

}

希望有所帮助。

删除文本文件中的一组数据

1 个答案: