Java EnumMap keySet()用法及代码示例

Java中的Java.util.EnumMap.keySet()方法用于返回映射中包含的键的设置视图。

用法:

Enum_Map.keySet()

参数：该方法不接受任何参数。

返回值：该方法返回映射中包含的键的设置视图。

以下示例程序旨在说明keySet()函数：

示例1:

// 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<gfg, String> mp = new 
                    EnumMap<gfg, String>(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<gfg> 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]

示例2:

// 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<gfg, Integer> mp =  
                new EnumMap<gfg, Integer>(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<gfg> 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]

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注：本文由纯净天空筛选整理自akash1295大神的英文原创作品 EnumMap keySet() Method in Java。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。