Java中的EnumMap entrySet()方法

Java中的Java .util.EnumMap.entrySet() 方法用于从 EnumMap 中包含的元素创建一个集合。它基本上返回枚举映射的集合视图。

句法：

enum_map.entrySet()

参数：该方法不带任何参数。

返回值：该方法返回此 enum_map 中包含的映射的集合视图。

下面的程序说明了 entrySet() 方法：

方案一：

// Java program to demonstrate entrySet() method
import java.util.*;
  
// An enum of gfg rank is created
public enum rank_countries {
    India,
    United_States,
    China,
    Japan,
    Canada,
    Russia
}
;
  
class Enum_map {
    public static void main(String[] args)
    {
  
        EnumMap mp = new 
        EnumMap(rank_countries.class);
  
        // Values are associated in mp
        mp.put(rank_countries.India, 72);
        mp.put(rank_countries.United_States, 1083);
        mp.put(rank_countries.China, 4632);
        mp.put(rank_countries.Japan, 6797);
  
        // Map view
        System.out.println("Map view: " + mp);
  
        // Creating a new set of the mappings
        // contained in map
        Set > set_view = 
                                                mp.entrySet();
  
        // Set view of the mappings
        System.out.println("Set view of the map: " + set_view);
    }
}

输出：

Map view: {India=72, United_States=1083, China=4632, Japan=6797}
Set view of the map: [India=72, United_States=1083, China=4632, Japan=6797]

方案二：

// Java program to demonstrate entrySet() method
import java.util.*;
  
// An enum of gfg ranking worldwide and in india
public enum gfg {
    Global_2018,
    India_2018
};
  
class Enum_map {
    public static void main(String[] args)
    {
  
        EnumMap mp = new 
              EnumMap(gfg.class);
  
        // Values are associated in mp
        mp.put(gfg.Global_2018, 800);
        mp.put(gfg.India_2018, 72);
  
        // Mapping view
        System.out.println("Mapping view: " + mp);
  
        // Creating a new set of the mappings 
        Set > set_view = 
                                    mp.entrySet();
  
        // Set view of the mappings
        System.out.println("Set view of the map: "
                                      + set_view);
    }
}

输出：

Mapping view: {Global_2018=800, India_2018=72}
Set view of the map: [Global_2018=800, India_2018=72]