Java开发任务跟踪：对象与状态管理实战

• TODO（待处理）
• IN_PROGRESS（进行中）
• DONE（已完成）

public class Task {
    private String id;
    private String title;
    private String description;
    private TaskStatus status;
    private LocalDateTime createdAt;
    private LocalDateTime updatedAt;

    public Task(String id, String title, String description) {
        this.id = id;
        this.title = title;
        this.description = description;
        this.status = TaskStatus.TODO;
        this.createdAt = LocalDateTime.now();
        this.updatedAt = LocalDateTime.now();
    }

    public void setStatus(TaskStatus newStatus) {
        if (newStatus == null) {
            throw new IllegalArgumentException("状态不能为null");
        }
        this.status = newStatus;
        this.updatedAt = LocalDateTime.now();
    }

    // Getter 和 Setter 方法省略，实际中需补全
    public String getId() { return id; }
    public String getTitle() { return title; }
    public TaskStatus getStatus() { return status; }
    public LocalDateTime getUpdatedAt() { return updatedAt; }

    @Override
    public String toString() {
        return "Task{" +
                "id='" + id + '\'' +
                ", title='" + title + '\'' +
                ", status=" + status +
                ", updatedAt=" + updatedAt +
                '}';
    }
}

public void setStatus(TaskStatus newStatus) {
    if (newStatus == null) {
        throw new IllegalArgumentException("状态不能为null");
    }
    if (this.status == TaskStatus.DONE && !this.status.equals(newStatus)) {
        throw new IllegalStateException("已完成的任务不可更改状态");
    }
    if (newStatus == TaskStatus.IN_PROGRESS && this.status != TaskStatus.TODO) {
        throw new IllegalStateException("只有待处理任务可进入进行中");
    }
    this.status = newStatus;
    this.updatedAt = LocalDateTime.now();
}

import java.util.HashMap;
import java.util.Map;

public class TaskManager {
    private Map tasks;

    public TaskManager() {
        this.tasks = new HashMap();
    }

    public void addTask(Task task) {
        tasks.put(task.getId(), task);
    }

    public Task getTask(String id) {
        return tasks.get(id);
    }

    public void updateTaskStatus(String id, TaskStatus status) {
        Task task = tasks.get(id);
        if (task != null) {
            task.setStatus(status);
        } else {
            throw new IllegalArgumentException("任务不存在：" + id);
        }
    }

    public void listAllTasks() {
        tasks.values().forEach(System.out::println);
    }
}

public class Main {
    public static void main(String[] args) {
        TaskManager manager = new TaskManager();

        Task task1 = new Task("001", "设计数据库表结构", "完成用户模块的表设计");
        Task task2 = new Task("002", "实现登录接口", "基于Spring Boot开发");

        manager.addTask(task1);
        manager.addTask(task2);

        manager.listAllTasks();

        manager.updateTaskStatus("001", TaskStatus.IN_PROGRESS);
        System.out.println("\n更新后：");
        manager.listAllTasks();
    }
}