Map接口 映射 沒有順序
???-|HashMap 管理鍵值對
???-|ConcurrentMap 線程安全
???-|LinkedHashMap

key：鍵
value：值

MyClass.java

class Person{
    int age;
    int score;
    String name;

    public Person (int age, int score, String name) {
        this.age = age;
        this.score = score;
        this.name = name;
    }

    @Override
    public String toString() {
        return "Person" +
            "age=" + age +;
    }
}


public class MyClass {
    public static void main(String[] agrs) {
        Map<String, Person> map = new HashMap<>();

        //添加一個鍵值對
        map.put(k: "jack", new Person(age: 30, score: 98, name: "jack"));
        map.put(k: "merry", new Person(age: 32, score: 62, name: "merry"));

        //獲取鍵值對的個數(shù)
        System.out.println(map.size());

        //是否包含某一個key
        System.out.println(map.containsKey(o: "jack232"));//false
        
        //判斷是否包含某個value
        System.out.println(map.containsValue(person));

        //獲取某個key對應(yīng)的value
        Person p = map.get("jack");
        System.out.println("jack:"+p);//jack:person{age=30, score=98, name='jack'}
        
        //刪除某個鍵值對
        map.remove(o: "jack");

        //替換某個鍵值對
        map.replace(k: "jack", new Person(age: 32, score: 32, name: "張三"));
        System.out.println(map);//jack=Person{age=32, score=32, name='張三'}

        //清空
        map.claer();
        
        //map遍歷
        Set<Map.Entry<String, Person>> entries = map.entrySet();
        for (Map.Entry<String, Person> entry: entries){
            System.out.println("key:"+entry.getKey()+" value:"+entry.getValue());
        }
        
    }