Java中的EnumMap equals（）方法及其示例-yiteyi-C++库

爪哇。util。地图。等于( obj )在Java中，用于将传递的对象与 这张地图 为了平等。必须记住，传递的对象必须是与EnumMap类型相同的映射。 语法：

null

boolean equals(Object obj)

参数： 该方法采用一个参数 obj 对象类型，并指要与此贴图进行比较的贴图。 返回值： 如果指定的对象等于映射，则该方法将返回true或false。下面的程序说明了equals（）方法的工作原理： 项目1：

JAVA

                         // Java program to demonstrate equals() method                       
                         import                                     java.util.*;                       
           
                         // An enum of gfg ranking worldwide and in India                       
                         public                                     enum                                     gfg {                       
                                                 Global_2018,                       
                                                 India_2018,                       
                                                 China_2018                       
                         }                       
                         ;                       
           
                         class                                     Enum_map {                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
           
                                                 EnumMap<gfg, Integer> mp1 =                                     new                                     EnumMap<gfg, Integer>(gfg.                                     class                                     );                       
           
                                                 EnumMap<gfg, Integer> mp2 =                                     new                                     EnumMap<gfg, Integer>(gfg.                                     class                                     );                       
           
                                                 // Values are associated in mp1                       
                                                 mp1.put(gfg.Global_2018,                                     800                                     );                       
                                                 mp1.put(gfg.India_2018,                                     72                                     );                       
           
                                                 // Values are associated in mp2                       
                                                 mp2.put(gfg.Global_2018,                                     800                                     );                       
                                                 mp2.put(gfg.India_2018,                                     72                                     );                       
           
                                                 // Stores the result                       
                                                 boolean                                     res1 = mp1.equals(mp2);                       
           
                                                 // Prints the result                       
                                                 System.out.println(                                     "Map1 equal to Map2: "                                     + res1);                       
           
                                                 mp2.put(gfg.China_2018,                                     1607                                     );                       
           
                                                 // Stores the result                       
                                                 boolean                                     res2 = mp1.equals(mp2);                       
           
                                                 // Prints the result                       
                                                 System.out.println(                                     "Map1 equal to Map2: "                                     + res2);                       
                                                 }                       
                         }                       

输出：

Map1 equal to Map2: trueMap1 equal to Map2: false

项目2：

JAVA

                         // Java program to demonstrate equals() method                       
                         import                                     java.util.*;                       
           
                         // an enum of gdp growth rate                       
                         // in recent years of India                       
                         public                                     enum                                     gdp {                       
                                                 Ind_2015,                       
                                                 Ind_2016,                       
                                                 Ind_2017,                       
                                                 Ind_2018,                       
                                                 Ind_2019                       
                         }                       
                         ;                       
           
                         class                                     Enum_map {                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 {                       
           
                                                 EnumMap<gdp, String> mp1 =                                     new                                     EnumMap<gdp, String>(gdp.                                     class                                     );                       
           
                                                 EnumMap<gdp, String> mp2 =                                     new                                     EnumMap<gdp, String>(gdp.                                     class                                     );                       
           
                                                 // Values are associated in mp1                       
                                                 mp1.put(gdp.Ind_2015,                                     "8.4"                                     );                       
                                                 mp1.put(gdp.Ind_2016,                                     "9.2"                                     );                       
                                                 mp1.put(gdp.Ind_2017,                                     "6.1"                                     );                       
                                                 mp1.put(gdp.Ind_2018,                                     "7.7"                                     );                       
           
                                                 // Values are associated in mp2                       
                                                 mp2.put(gdp.Ind_2015,                                     "8.4"                                     );                       
                                                 mp2.put(gdp.Ind_2016,                                     "9.2"                                     );                       
                                                 mp2.put(gdp.Ind_2017,                                     "6.1"                                     );                       
                                                 mp2.put(gdp.Ind_2018,                                     "7.7"                                     );                       
           
                                                 // Stores the result                       
                                                 boolean                                     res1 = mp1.equals(mp2);                       
           
                                                 // Prints the result                       
                                                 System.out.println(                                     "Map1 equal to Map2: "                                     + res1);                       
           
                                                 mp2.put(gdp.Ind_2019,                                     "7.0"                                     );                       
           
                                                 // Stores the result                       
                                                 boolean                                     res2 = mp1.equals(mp2);                       
           
                                                 // Prints the result                       
                                                 System.out.println(                                     "Map1 equal to Map2: "                                     + res2);                       
                                                 }                       
                         }                       

输出：

Map1 equal to Map2: trueMap1 equal to Map2: false

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