java小型记事本代码

Java小型记事本代码的实现可以基于Swing组件库，以下是一个简单的Java小型记事本的代码示例：

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

public class JavaNotepad extends JFrame implements ActionListener {
    JTextArea area = new JTextArea(20,120);
    JMenuBar mb = new JMenuBar();
    JMenu file = new JMenu("文件");
    JMenuItem open = new JMenuItem("打开");
    JMenuItem save = new JMenuItem("保存");
    JMenuItem exit = new JMenuItem("退出");

    public JavaNotepad() {
        JScrollPane scroll = new JScrollPane(area);
        area.setFont(new Font("宋体",Font.BOLD,20));
        add(scroll,BorderLayout.CENTER);
        setJMenuBar(mb);
        mb.add(file);
        file.add(open);
        file.add(save);
        file.add(exit);
        open.addActionListener(this);
        save.addActionListener(this);
        exit.addActionListener(this);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == open)
            openFile();
        else if (e.getSource() == save)
            saveFile();
        else if (e.getSource() == exit)
            System.exit(0);
    }

    public void openFile() {
        JFileChooser chooser = new JFileChooser();
        int option = chooser.showOpenDialog(this);
        if (option == JFileChooser.APPROVE_OPTION) {
            area.setText("");
            try {
                Scanner scan = new Scanner(new FileReader(chooser.getSelectedFile().getPath()));
                while (scan.hasNext())
                    area.append(scan.nextLine() + "\n");
            } catch (Exception ex) {
                System.out.println(ex.getMessage());
            }
        }
    }

    public void saveFile() {
        JFileChooser chooser = new JFileChooser();
        int option = chooser.showSaveDialog(this);
        if (option == JFileChooser.APPROVE_OPTION) {
            try {
                BufferedWriter out = new BufferedWriter(new FileWriter(chooser.getSelectedFile().getPath()));
                out.write(area.getText());
                out.close();
            } catch (Exception ex) {
                System.out.println(ex.getMessage());
            }
        }
    }

    public static void main(String[] args) {
        JavaNotepad editor = new JavaNotepad();
        editor.setDefaultCloseOperation(EXIT_ON_CLOSE);
        editor.pack();
        editor.setVisible(true);
        editor.setLocationRelativeTo(null);
    }
}

该记事本可以打开、保存、退出文件，功能简单，适合初学者学习。