java - Java 中受密码保护的记事本问题

Question

我无法理解为什么我的代码无法运行。

就目前情况而言，Eclipse 没有向我显示任何错误，但当我尝试运行该代码时，该代码不会启动。

我的程序的想法是使用 JFrame 的密码保护记事本。

这是代码:

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

public class notepad extends JFrame implements ActionListener {
    public static void main(String args[]){}
    private TextArea textArea = new TextArea("", 0,0, TextArea.SCROLLBARS_VERTICAL_ONLY);
    private MenuBar menuBar = new MenuBar();
    private Menu file = new Menu();
    private MenuItem openFile = new MenuItem(); 
    private MenuItem saveFile = new MenuItem();
    private MenuItem close = new MenuItem(); 
    public notepad() {
        this.setSize(700, 500); 
        this.setTitle("Projet Java"); 
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        this.textArea.setFont(new Font("Helvetica", Font.ROMAN_BASELINE, 12));
        this.getContentPane().setLayout(new BorderLayout()); 
        this.getContentPane().add(textArea);
        this.setMenuBar(this.menuBar);
        this.menuBar.add(this.file); 
        this.file.setLabel("File");
        this.openFile.setLabel("Open");
        this.openFile.addActionListener(this);
        this.file.add(this.openFile); 
        this.saveFile.setLabel("Save");
        this.saveFile.addActionListener(this);
        this.file.add(this.saveFile);
    }

    public void actionPerformed (ActionEvent e) {
        if (e.getSource() == this.close)
            this.dispose(); 
        else if (e.getSource() == this.openFile) {
            JFileChooser open = new JFileChooser(); 
            int option = open.showOpenDialog(this); 
            if (option == JFileChooser.APPROVE_OPTION) {
                this.textArea.setText(""); 
                try {
                    Scanner scan = new Scanner(new FileReader(open.getSelectedFile().getPath()));
                    while (scan.hasNext())
                        this.textArea.append(scan.nextLine() + "\n"); 
                } catch (Exception ex) { 
                    System.out.println(ex.getMessage());
                }
            }
        }
        else if (e.getSource() == this.saveFile) {
            JFileChooser save = new JFileChooser(); 
            int option = save.showSaveDialog(this); 
            if (option == JFileChooser.APPROVE_OPTION) {
                try {
                    BufferedWriter out = new BufferedWriter(new FileWriter(save.getSelectedFile().getPath()));
                    out.write(this.textArea.getText());
                    out.close(); 
                } catch (Exception ex) { 
                    System.out.println(ex.getMessage());
                }
            }
        }
    }
        static class password{ 
        public static String password = "password";

        public static void main(String args[]) {
                JFrame box = new JFrame("Password");
                box.setVisible(true);
                box.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                box.setSize(400,100);

                JPasswordField pass = new JPasswordField(10);
                pass.setEchoChar('*');  
            }
                static class AL implements ActionListener{
                    public void actionPerformed(ActionEvent e){
                    JPasswordField input = (JPasswordField) e.getSource();
                    char[] pass = input.getPassword();
                    String yes = new String(pass);

                    if (yes.equals(password)){ 
                        notepad app = new notepad();
                        app.setVisible(true);
                    }else{
                        System.exit(0);
                    }


                    }
                }
        }
}

Answer 1

• 您的第一个 main 方法是公共(public)的，但为空，因此不会执行任何操作。
• 您的第二个 main 方法位于非公共(public)类中，因此 JVM 永远不会找到它来启动您的程序。
• 将 AWT 图形组件与 Swing 图形组件混合使用，规则是选择其中一种，切勿混合使用两者。
• 所有 Swing 应用程序都应在 SwingUtilities.invokeLater 内启动，以确保修改 GUI 的所有线程均由事件调度程序线程 (EDT) 执行。
• 使用 JTextArea 时，始终将其放在 JScrollPane 内，以便能够到达组件大小之外显示的文本。

这是用于测试的修改代码:

import java.awt.Font;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;

import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

@SuppressWarnings("serial")
public class Notepad extends JFrame
{
    public static void main(String args[])
    {
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                try
                {
                    UIManager.setLookAndFeel(
                            "javax.swing.plaf.nimbus.NimbusLookAndFeel");
                }
                catch (ClassNotFoundException | InstantiationException
                        | IllegalAccessException
                        | UnsupportedLookAndFeelException e)
                {
                    e.printStackTrace();
                }
                new Notepad();
            }
        });
    }

    private JTextArea textArea = new JTextArea("", 0, 0);
    private JMenuBar menuBar = new JMenuBar();
    private JMenu file = new JMenu();
    private JMenuItem openFile = new JMenuItem();
    private JMenuItem saveFile = new JMenuItem();
    private JMenuItem close = new JMenuItem();
    private JFileChooser open, save;

    public Notepad()
    {
        setBounds(100, 100, 700, 500);
        setTitle("Projet Java");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        textArea.setFont(new Font("Helvetica", Font.ROMAN_BASELINE, 12));
        add(new JScrollPane(textArea));

        open = new JFileChooser();
        save = new JFileChooser();

        setJMenuBar(menuBar);
        menuBar.add(file);
        file.setText("File");

        openFile.setText("Open");
        openFile.addActionListener(e -> {
            if (open.showOpenDialog(
                    Notepad.this) == JFileChooser.APPROVE_OPTION)
            {
                textArea.setText("");
                try (BufferedReader br = new BufferedReader(
                        new FileReader(open.getSelectedFile())))
                {
                    String s = null;
                    while ((s = br.readLine()) != null)
                    {
                        textArea.append(s + "\n");
                    }
                }
                catch (Exception ex)
                {
                    System.out.println(ex.getMessage());
                }
            }
        });
        file.add(openFile);

        saveFile.setText("Save");
        saveFile.addActionListener(e -> {
            if (save.showSaveDialog(
                    Notepad.this) == JFileChooser.APPROVE_OPTION)
            {
                try (BufferedWriter out = new BufferedWriter(
                        new FileWriter(save.getSelectedFile())))
                {
                    out.write(textArea.getText());
                }
                catch (Exception ex)
                {
                    System.out.println(ex.getMessage());
                }
            }
        });
        file.add(saveFile);

        close.setText("Close");
        close.addActionListener(e -> {
            System.exit(0);
        });
        file.add(close);

        setVisible(true);
    }
}