• Junit 的使用

1. 为了方便程序员测试某一个方法而使用

2. 在方法上面加上 @Test 并引用 5.X 版本

3. 就能在方法前面看到可运行的按钮

public class Homework07 {
    public static void main(String[] args) {
    }

    @Test
    public void testList() {
        DAO<User> dao = new DAO<>();
        dao.save("第一个", new User(123, 23, "小米"));
        dao.save("第二个", new User(234, 32, "小华"));
        dao.save("第三个", new User(345, 66, "小钟"));
        dao.save("第四个", new User(456, 45, "小三"));
        List<User> list1 = dao.list();
        System.out.println(list1);
        dao.update("第二个",new User(555, 78, "小小"));
        List<User> list2 = dao.list();
        System.out.println(list2);
        dao.delete("第一个");
        List<User> list3 = dao.list();
        System.out.println(list3);
    }
}

class DAO<T> {
    private Map<String, T> map = new HashMap<>();

    public void save(String id, T entity) {
        getMap().put(id, entity);
    }

    public T get(String id) {
        return getMap().get(id);
    }

    public void update(String id, T entity) {
        getMap().put(id, entity);
    }

    public List<T> list() {
        ArrayList<T> list = new ArrayList<>();

        Set<String> strings = getMap().keySet();
        for (String key : strings) {
            list.add(getMap().get(key));
        }
        return list;
        // return new ArrayList<>(getMap().values());
    }

    public void delete(String id) {
        getMap().remove(id);
    }

    public Map<String, T> getMap() {
        return map;
    }

    public void setMap(Map<String, T> map) {
        this.map = map;
    }
}

class User {
    private int id;
    private int age;
    private String name;

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", age=" + age +
                ", name='" + name + '\'' +
                '}';
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        User user = (User) o;
        return id == user.id && age == user.age && Objects.equals(name, user.name);
    }

    @Override
    public int hashCode() {
        return Objects.hash(id, age, name);
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public User(int id, int age, String name) {
        this.id = id;
        this.age = age;
        this.name = name;
    }
}

运行结果：

[User{id=234, age=32, name='小华'}, User{id=456, age=45, name='小三'}, User{id=345, age=66, name='小钟'}, User{id=123, age=23, name='小米'}]
[User{id=555, age=78, name='小小'}, User{id=456, age=45, name='小三'}, User{id=345, age=66, name='小钟'}, User{id=123, age=23, name='小米'}]
[User{id=555, age=78, name='小小'}, User{id=456, age=45, name='小三'}, User{id=345, age=66, name='小钟'}]