Java中的EnumMap keySet（）方法-yiteyi-C++库

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

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语法：

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集合视图。

下面的程序演示了keySet（）函数：

项目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]

项目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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