Java中的WeakHashMap size（）方法-yiteyi-C++库

爪哇。util。WeakHashMap。WeakHashMap类的size（）方法用于获取映射的大小，该大小表示映射中键值对或映射的数量。

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语法：

WeaK_Hash_Map.size()

参数： 该方法不采用任何参数。

返回值： 该方法返回映射的大小，这也意味着映射中存在的键值对的数量。

下面的程序演示了java。util。WeakHashMap。size（）方法：

方案1 :

                     // Java code to illustrate the size() method                   
                     import                               java.util.*;                   
                             
                     public                               class                               Weak_Hash_Map_Demo {                   
                                         public                               static                               void                               main(String[] args)                   
                                         {                   
                             
                                         // Creating an empty WeakHashMap                   
                                         Map<Integer, String> weak_hash =                               new                   
                                         WeakHashMap<Integer, String>();                   
                             
                                         // Mapping string values to int keys                   
                                         weak_hash.put(                               10                               ,                               "Geeks"                               );                   
                                         weak_hash.put(                               15                               ,                               "4"                               );                   
                                         weak_hash.put(                               20                               ,                               "Geeks"                               );                   
                                         weak_hash.put(                               25                               ,                               "Welcomes"                               );                   
                                         weak_hash.put(                               30                               ,                               "You"                               );                   
                             
                                         // Displaying the WeakHashMap                   
                                         System.out.println(                               "Initial Mappings are: "                               +                   
                                         weak_hash);                   
                             
                                         // Displaying the size of the map                   
                                         System.out.println(                               "The size of the map is "                               +                   
                                         weak_hash.size());                   
                                         }                   
                     }                   

输出：

Initial Mappings are: {30=You, 15=4, 10=Geeks, 25=Welcomes, 20=Geeks}
The size of the map is 5

项目2：

                     // Java code to illustrate the size() method                   
                     import                               java.util.*;                   
                             
                     public                               class                               Weak_Hash_Map_Demo {                   
                                         public                               static                               void                               main(String[] args)                   
                                         {                   
                             
                                         // Creating an empty WeakHashMap                   
                                         Map<String, Integer> weak_hash =                               new                   
                                         WeakHashMap<String, Integer>();                   
                             
                                         // Mapping int values to string keys                   
                                         weak_hash.put(                               "Geeks"                               ,                               10                               );                   
                                         weak_hash.put(                               "4"                               ,                               15                               );                   
                                         weak_hash.put(                               "Geeks"                               ,                               20                               );                   
                                         weak_hash.put(                               "Welcomes"                               ,                               25                               );                   
                                         weak_hash.put(                               "You"                               ,                               30                               );                   
                             
                                         // Displaying the WeakHashMap                   
                                         System.out.println(                               "Initial Mappings are: "                               +                   
                                         weak_hash);                   
                             
                                         // Displaying the size of the map                   
                                         System.out.println(                               "The size of the map is "                               +                   
                                         weak_hash.size());                   
                                         }                   
                     }                   

输出：

Initial Mappings are: {Welcomes=25, 4=15, You=30, Geeks=20}
The size of the map is 4

注：相同的操作可以在不同数据类型的变化和组合的任何类型的映射中执行。

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