Java如何开发一个简易的备忘录小程序

public class Memo {
    private String title;
    private String content;
    private String timestamp;

    public Memo(String title, String content) {
        this.title = title;
        this.content = content;
        this.timestamp = java.time.LocalDateTime.now().toString();
    }

    // Getter 方法
    public String getTitle() { return title; }
    public String getContent() { return content; }
    public String getTimestamp() { return timestamp; }

    @Override
    public String toString() {
        return "标题: " + title + "\n内容: " + content + "\n时间: " + timestamp + "\n" + "-".repeat(30);
    }
}

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

public class MemoApp {
    private static final String FILE_NAME = "memos.txt";
    private List<Memo> memos = new ArrayList<>();
    private Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {
        new MemoApp().run();
    }

    private void run() {
        loadFromFile(); // 启动时加载数据
        while (true) {
            showMenu();
            int choice = getIntInput();
            switch (choice) {
                case 1 -> addMemo();
                case 2 -> viewMemos();
                case 3 -> deleteMemo();
                case 4 -> saveAndExit();
                default -> System.out.println("无效选择，请重试");
            }
        }
    }

    private void showMenu() {
        System.out.println("\n=== 简易备忘录 ===");
        System.out.println("1. 添加备忘录");
        System.out.println("2. 查看所有备忘录");
        System.out.println("3. 删除备忘录");
        System.out.println("4. 退出并保存");
        System.out.print("请选择操作：");
    }

    private void addMemo() {
        System.out.print("请输入标题：");
        String title = scanner.nextLine();
        System.out.print("请输入内容：");
        String content = scanner.nextLine();
        memos.add(new Memo(title, content));
        System.out.println("备忘录已添加！");
    }

    private void viewMemos() {
        if (memos.isEmpty()) {
            System.out.println("暂无备忘录");
            return;
        }
        for (int i = 0; i < memos.size(); i++) {
            System.out.println("编号 " + i + ":\n" + memos.get(i));
        }
    }

    private void deleteMemo() {
        viewMemos();
        if (memos.isEmpty()) return;
        System.out.print("请输入要删除的编号：");
        int index = getIntInput();
        if (index >= 0 && index < memos.size()) {
            memos.remove(index);
            System.out.println("已删除！");
        } else {
            System.out.println("编号无效");
        }
    }

    private int getIntInput() {
        while (!scanner.hasNextInt()) {
            scanner.next();
            System.out.print("请输入数字：");
        }
        int value = scanner.nextInt();
        scanner.nextLine(); // 消费换行符
        return value;
    }

    private void loadFromFile() {
        File file = new File(FILE_NAME);
        if (!file.exists()) return;

        try (BufferedReader br = new BufferedReader(new FileReader(file))) {
            String line;
            while ((line = br.readLine()) != null) {
                if (line.startsWith("标题:")) {
                    String title = line.substring(3);
                    String content = br.readLine().substring(3);
                    String time = br.readLine().substring(3);
                    Memo memo = new Memo("", "");
                    // 反射或手动设置私有字段（简化版可用构造后修改）
                    // 实际项目建议用JSON或序列化
                    System.out.println("加载：" + title);
                }
            }
        } catch (IOException e) {
            System.out.println("读取文件失败：" + e.getMessage());
        }
    }

    private void saveAndExit() {
        try (PrintWriter pw = new PrintWriter(new FileWriter(FILE_NAME))) {
            for (Memo memo : memos) {
                pw.println("标题: " + memo.getTitle());
                pw.println("内容: " + memo.getContent());
                pw.println("时间: " + memo.getTimestamp());
                pw.println("------------------------");
            }
            System.out.println("数据已保存，程序退出。");
        } catch (IOException e) {
            System.out.println("保存失败：" + e.getMessage());
        }
        System.exit(0);
    }
}