Java中的 EnumMap keySet() 方法

Java中的Java .util.EnumMap.keySet() 方法用于返回映射中包含的键的集合视图。

句法：

Enum_Map.keySet()

参数：该方法不接受任何参数。

返回值：该方法返回地图中包含的键的集合视图。

下面的程序说明了 keySet()函数：

方案一：

// Java program to demonstrate keySet()
import java.util.*;
  
// An enum of geeksforgeeks
public enum gfg {
    India,
    United_States,
    China
};
  
class Enum_demo {
    public static void main(String[] args)
    {
  
        EnumMap mp = new 
                    EnumMap(gfg.class);
  
        // Values are associated
        mp.put(gfg.India, "61.7%");
        mp.put(gfg.United_States, "18.2%");
        mp.put(gfg.China, "2.5%");
  
        // Prints the map
        System.out.println("Mappings: " + mp);
  
        // Store the set view of the key
        Set set_view = mp.keySet();
  
        // Print the result
        System.out.println("Set view of the key: " + 
                                            set_view);
    }
}

输出：

Mappings: {India=61.7%, United_States=18.2%, China=2.5%}
Set view of the key: [India, United_States, China]

方案二：

// Java program to demonstrate keySet()
import java.util.*;
  
// An enum of geeksforgeeks
public enum gfg {
    Global_today,
    India_today
};
  
class Enum_demo {
    public static void main(String[] args)
    {
  
        EnumMap mp = 
                new EnumMap(gfg.class);
  
        // Values are associated
        mp.put(gfg.Global_today, 799);
        mp.put(gfg.India_today, 69);
  
        // Prints the map
        System.out.println("Mappings: " + mp);
  
        // Store the set view of the key
        Set set_view = mp.keySet();
  
        // Print the result
        System.out.println("Set view of the key: " +
                                             set_view);
    }
}

输出：

Mappings: {Global_today=799, India_today=69}
Set view of the key: [Global_today, India_today]