Java中的EnumMap size（）方法-yiteyi-C++库

爪哇。util。地图。java中的size（）方法用于知道映射的大小或映射中存在的元素数。

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语法：

Enum_Map.size()

参数： 该方法不采用任何参数。

返回值： 该方法返回地图的大小。

下面的程序说明了size（）函数的工作原理： 项目1：

                     // Java program to demonstrate size()                   
                     import                               java.util.*;                   
                             
                     // An enum of geeksforgeeks                   
                     public                               enum                               gfg {                   
                                         India_today,                   
                                         United_States_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.India_today,                               69                               );                   
                                         mp.put(gfg.United_States_today,                               1073                               );                   
                             
                                         // Prints the map                   
                                         System.out.println(                               "The EnumMap: "                               + mp);                   
                             
                                         // Store the size of the map                   
                                         int                               numberOf_kv = mp.size();                   
                             
                                         // Prints the map_size                   
                                         System.out.println(                               "Size of map: "                               + numberOf_kv);                   
                                         }                   
                     }                   

输出：

The EnumMap: {India_today=69, United_States_today=1073}
Size of map: 2

项目2：

                     // Java program to demonstrate size()                   
                     import                               java.util.*;                   
                             
                     // An enum of geeksforgeeks                   
                     public                               enum                               gfg {                   
                             
                                         India_today,                   
                                         United_States_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.India_today,                               69                               );                   
                                         mp.put(gfg.United_States_today,                               1073                               );                   
                             
                                         // Prints the map                   
                                         System.out.println(                               "The EnumMap: "                               + mp);                   
                             
                                         // Remove mapping of this key                   
                                         mp.remove(gfg.United_States_today);                   
                             
                                         // Prints the final map                   
                                         System.out.println(                               "The EnumMap: "                               + mp);                   
                             
                                         // Store the size pf map after removal of                   
                                         // The key                   
                                         int                               numberOf_kv = mp.size();                   
                             
                                         // Prints the map_size                   
                                         System.out.println(                               "Size of map: "                               + numberOf_kv);                   
                                         }                   
                     }                   

输出：

The EnumMap: {India_today=69, United_States_today=1073}
The EnumMap: {India_today=69}
Size of map: 1

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