使用java编写的记事本程序代码

以下是一个简单的Java Swing记事本程序的代码，你可以参考它来编写你自己的程序：

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

public class SimpleNotepad extends JFrame implements ActionListener {
    private JTextArea textArea;
    private JScrollPane scrollPane;
    private JMenuBar menuBar;
    private JMenu fileMenu, editMenu;
    private JMenuItem newFileItem, openFileItem, saveFileItem, saveAsFileItem, exitFileItem;
    private JMenuItem undoItem, redoItem, cutItem, copyItem, pasteItem, selectAllItem;

    private File currentFile;

    public SimpleNotepad() {
        super("Simple Notepad");

        textArea = new JTextArea(20, 60);
        textArea.setFont(new Font("Consolas", Font.PLAIN, 14));

        scrollPane = new JScrollPane(textArea);

        menuBar = new JMenuBar();

        fileMenu = new JMenu("File");
        newFileItem = new JMenuItem("New");
        openFileItem = new JMenuItem("Open");
        saveFileItem = new JMenuItem("Save");
        saveAsFileItem = new JMenuItem("Save As");
        exitFileItem = new JMenuItem("Exit");

        editMenu = new JMenu("Edit");
        undoItem = new JMenuItem("Undo");
        redoItem = new JMenuItem("Redo");
        cutItem = new JMenuItem("Cut");
        copyItem = new JMenuItem("Copy");
        pasteItem = new JMenuItem("Paste");
        selectAllItem = new JMenuItem("Select All");

        newFileItem.addActionListener(this);
        openFileItem.addActionListener(this);
        saveFileItem.addActionListener(this);
        saveAsFileItem.addActionListener(this);
        exitFileItem.addActionListener(this);
        undoItem.addActionListener(this);
        redoItem.addActionListener(this);
        cutItem.addActionListener(this);
        copyItem.addActionListener(this);
        pasteItem.addActionListener(this);
        selectAllItem.addActionListener(this);

        fileMenu.add(newFileItem);
        fileMenu.add(openFileItem);
        fileMenu.add(saveFileItem);
        fileMenu.add(saveAsFileItem);
        fileMenu.addSeparator();
        fileMenu.add(exitFileItem);

        editMenu.add(undoItem);
        editMenu.add(redoItem);
        editMenu.addSeparator();
        editMenu.add(cutItem);
        editMenu.add(copyItem);
        editMenu.add(pasteItem);
        editMenu.addSeparator();
        editMenu.add(selectAllItem);

        menuBar.add(fileMenu);
        menuBar.add(editMenu);

        setJMenuBar(menuBar);
        add(scrollPane);

        setSize(800, 600);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setVisible(true);
    }

    public static void main(String[] args) {
        new SimpleNotepad();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == newFileItem) {
            newFile();
        } else if (e.getSource() == openFileItem) {
            openFile();
        } else if (e.getSource() == saveFileItem) {
            saveFile();
        } else if (e.getSource() == saveAsFileItem) {
            saveAsFile();
        } else if (e.getSource() == exitFileItem) {
            exit();
        } else if (e.getSource() == undoItem) {
            textArea.undo();
        } else if (e.getSource() == redoItem) {
            textArea.redo();
        } else if (e.getSource() == cutItem) {
            textArea.cut();
        } else if (e.getSource() == copyItem) {
            textArea.copy();
        } else if (e.getSource() == pasteItem) {
            textArea.paste();
        } else if (e.getSource() == selectAllItem) {
            textArea.selectAll();
        }
    }

    private void newFile() {
        textArea.setText("");
        currentFile = null;
    }

    private void openFile() {
        JFileChooser fileChooser = new JFileChooser(".");
        int result = fileChooser.showOpenDialog(this);
        if (result == JFileChooser.APPROVE_OPTION) {
            File file = fileChooser.getSelectedFile();
            try {
                FileReader reader = new FileReader(file);
                textArea.read(reader, null);
                reader.close();
                currentFile = file;
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private void saveFile() {
        if (currentFile != null) {
            try {
                FileWriter writer = new FileWriter(currentFile);
                textArea.write(writer);
                writer.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else {
            saveAsFile();
        }
    }

    private void saveAsFile() {
        JFileChooser fileChooser = new JFileChooser(".");
        int result = fileChooser.showSaveDialog(this);
        if (result == JFileChooser.APPROVE_OPTION) {
            File file = fileChooser.getSelectedFile();
            try {
                FileWriter writer = new FileWriter(file);
                textArea.write(writer);
                writer.close();
                currentFile = file;
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private void exit() {
        System.exit(0);
    }
}

这个程序的功能包括新建、打开、保存、另存为、撤销、重做、剪切、复制、粘贴、选择全部等功能。注意，这只是一个简单的示例程序，你可以根据实际需求进行修改和扩展。