Java Map.Entry 接口详细介绍

清疚 2023-09-24 19:03 65阅读 0赞

# 1. 定义 #

*  Java 中的 Map.Entry 接口提供了一些方法来访问 Map
 *  `Map.Entry` 是`一个泛型`，在`java.util` 包中定义。
 *  `Interface Map.Entry k -> Key V -> Value`

# 2. 方法： #

## 1.equals (Object o) ##

比较对象（调用对象）与对象 o 是否相等

boolean equals(Object o)
    Parameters :
    o -> Object to which we want to compare
    Returns:
    true: if both objects are equals
    false: otherwise

## 2.K getKey() – 返回相应映射条目的键。 ##

K getKey()
    Parameters :
    -------------
    Returns:
    K -> Returns the corresponding Key of a entry on which it is invoked

## 3.V getValue() – 返回相应映射条目的值。 ##

V getValue()
    Parameters :
    -------------
    Returns:
    V -> Returns the corresponding value of a entry on which it is invoked

## 4.int hashcode() – 返回相应映射条目的哈希码 ##

int hashcode()
    Parameters :
    -------------
    Returns:
    int -> Returns the hash-code of entry on which it is invoked

## 5.V setValue(V v) – 设置具有指定值 v 的地图的值 ##

V setValue(V v)
    Parameters :
    v -> Value which was earlier stored in the entry on which it is invoked
    Returns:
    int -> Returns the hash-code of a entry on which it is invoked

## 6.Set<Map.Entry> entrySet() – 返回整个地图的集合视图。 ##

Set<Map.Entry> entrySet() 
    Parameters :
    ---------------
    Returns:
    Set<Map.Entry> ->: Returns a Set containing the Map.Entry values

# 3.代码 #

## **Iterator遍历结果** ##

public class GFG {
        
        public static void main(String[] args) {
        
            Map<String,Integer> map = new HashMap<String,Integer>();
            map.put("a",1);
            map.put("b",2);
            map.put("c",3);
            map.put("d",4);
            Set<Map.Entry<String,Integer>> set = map.entrySet();
            Iterator<Map.Entry<String, Integer>> itr = set.iterator();
            while(itr.hasNext()){
        
                Map.Entry<String, Integer> entry = itr.next();
                System.out.println(entry.getKey()+" "+entry.getValue());
    
            }
    
        }
    }

a 1
    b 2
    c 3
    d 4

## for循环遍历结果 ##

public class GFG {
        
        public static void main(String[] args) {
        
            Map<String,Integer> map = new HashMap<String,Integer>();
            map.put("a",1);
            map.put("b",2);
            map.put("c",3);
            map.put("d",4);
            Set<Map.Entry<String,Integer>> set = map.entrySet();
    
            for(Map.Entry<String,Integer> s:set){
        
                System.out.println(s.getKey()+" "+s.getValue());
            }
    
    
        }
    }

a 1
    b 2
    c 3
    d 4