Java如何开发一个小型待办事项管理系统

public class Task {
    private int id;
    private String description;
    private boolean completed;

    public Task(int id, String description) {
        this.id = id;
        this.description = description;
        this.completed = false;
    }

    // Getter 和 Setter 方法
    public int getId() { return id; }
    public String getDescription() { return description; }
    public boolean isCompleted() { return completed; }
    public void setCompleted(boolean completed) { this.completed = completed; }

    @Override
    public String toString() {
        return id + ". " + description + " [" + (completed ? "完成" : "未完成" + "]");
    }
}

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

public class TodoManager {
    private List<Task> tasks;
    private static final String FILE_NAME = "tasks.txt";
    private int nextId;

    public TodoManager() {
        tasks = new ArrayList<>();
        nextId = 1;
        loadFromFile(); // 启动时加载数据
    }

    public void addTask(String desc) {
        tasks.add(new Task(nextId++, desc));
        saveToFile();
    }

    public void viewTasks() {
        if (tasks.isEmpty()) {
            System.out.println("暂无任务。");
        } else {
            for (Task task : tasks) {
                System.out.println(task);
            }
        }
    }

    public boolean markAsCompleted(int id) {
        for (Task task : tasks) {
            if (task.getId() == id) {
                task.setCompleted(true);
                saveToFile();
                return true;
            }
        }
        return false;
    }

    public boolean deleteTask(int id) {
        Iterator<Task> it = tasks.iterator();
        while (it.hasNext()) {
            if (it.next().getId() == id) {
                it.remove();
                saveToFile();
                return true;
            }
        }
        return false;
    }

    private void saveToFile() {
        try (ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(FILE_NAME))) {
            out.writeObject(tasks);
            out.writeInt(nextId);
        } catch (IOException e) {
            System.out.println("保存失败：" + e.getMessage());
        }
    }

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

        try (ObjectInputStream in = new ObjectInputStream(new FileInputStream(file))) {
            tasks = (List<Task>) in.readObject();
            nextId = in.readInt();
        } catch (IOException | ClassNotFoundException e) {
            System.out.println("读取数据失败，使用空列表。");
        }
    }
}

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        TodoManager manager = new TodoManager();
        Scanner scanner = new Scanner(System.in);
        String cmd;

        System.out.println("欢迎使用待办事项系统！");

        while (true) {
            System.out.println("\n输入命令：add(添加), view(查看), done(完成), del(删除), exit(退出)");
            cmd = scanner.nextLine().trim().toLowerCase();

            switch (cmd) {
                case "add":
                    System.out.print("请输入任务内容：");
                    String desc = scanner.nextLine();
                    if (!desc.trim().isEmpty()) {
                        manager.addTask(desc);
                        System.out.println("任务已添加。");
                    }
                    break;

                case "view":
                    manager.viewTasks();
                    break;

                case "done":
                    System.out.print("请输入要完成的任务编号：");
                    try {
                        int id = Integer.parseInt(scanner.nextLine());
                        if (manager.markAsCompleted(id)) {
                            System.out.println("任务已标记为完成。");
                        } else {
                            System.out.println("未找到该任务。");
                        }
                    } catch (NumberFormatException e) {
                        System.out.println("请输入有效编号。");
                    }
                    break;

                case "del":
                    System.out.print("请输入要删除的任务编号：");
                    try {
                        int id = Integer.parseInt(scanner.nextLine());
                        if (manager.deleteTask(id)) {
                            System.out.println("任务已删除。");
                        } else {
                            System.out.println("未找到该任务。");
                        }
                    } catch (NumberFormatException e) {
                        System.out.println("请输入有效编号。");
                    }
                    break;

                case "exit":
                    System.out.println("再见！");
                    scanner.close();
                    return;

                default:
                    System.out.println("无效命令，请重试。");
            }
        }
    }
}