用java编写一个记事本

在Java中编写一个简单的文本编辑器（记事本），我们可以创建一个基于控制台的应用程序。这里是一个基础的例子，它允许用户打开、读取和保存文本文件：

import java.io.*;
import java.util.Scanner;

class SimpleNotebook {
    private String filePath;

    public void openFile(String fileName) {
        try {
            filePath = "notes/" + fileName;
            if (new File(filePath).exists()) {
                Scanner scanner = new Scanner(new FileReader(filePath));
                System.out.println("Content of the file:");
                while (scanner.hasNextLine()) {
                    System.out.println(scanner.nextLine());
                }
                scanner.close();
            } else {
                System.out.println("File not found.");
            }
        } catch (FileNotFoundException e) {
            System.out.println("Error opening file.");
            e.printStackTrace();
        }
    }

    public void saveFile() {
        try {
            BufferedWriter writer = new BufferedWriter(new FileWriter(filePath));
            writer.write("Enter your text to save:");
            writer.newLine();
            writer.write(Console.input());
            writer.close();
            System.out.println("Text saved successfully.");
        } catch (IOException e) {
            System.out.println("Error saving file.");
            e.printStackTrace();
        }
    }
}

public class Main {
    public static void main(String[] args) {
        SimpleNotebook notebook = new SimpleNotebook();
        Scanner input = new Scanner(System.in);
        System.out.println("Welcome to Simple Text Editor!");
        while (true) {
            System.out.println("\n1. Open an existing file");
            System.out.println("2. Save a new file");
            System.out.println("3. Exit");
            int choice = input.nextInt();

            switch (choice) {
                case 1:
                    System.out.print("Enter file name: ");
                    String fileName = input.next();
                    notebook.openFile(fileName);
                    break;
                case 2:
                    notebook.saveFile();
                    break;
                case 3:
                    System.exit(0);
                    break;
                default:
                    System.out.println("Invalid option, please try again.");
            }
        }
    }
}

在这个例子中，`SimpleNotebook`类包含两个方法：`openFile`用于显示并读取文件内容，`saveFile`用于接收用户的输入并将其保存到指定文件。主函数提供了一个简单的菜单，让用户选择操作。