• 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

java">public class Homework07 {public static void main(String[] args) {}@Testpublic 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;@Overridepublic String toString() {return "User{" +"id=" + id +", age=" + age +", name='" + name + '\'' +'}';}@Overridepublic 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);}@Overridepublic 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'}]