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  • 2018-08-07  21:51:05        
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    Java中的java.util.IdentityHashMap.entrySet()方法用于创建映射中包含的相同元素的集合。它基本上返回了哈希映射的map集合,或者我们可以创建一个新集合并将地图元素存储到它们中。

    句法:

    Identity_HashMap.entrySet()

    参数:该方法不带任何参数。

    返回值:该方法返回一个具有与map相同元素的集合。

    下面的程序说明了java.util.IdentityHashMap.entrySet()方法

    程序1:将字符串值映射到整数键。

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

    输出:

    Initial Mappings are: {10=Geeks, 30=You, 20=Geeks, 25=Welcomes, 15=4}
    The set is: [10=Geeks, 30=You, 20=Geeks, 25=Welcomes, 15=4]

    程序2:将整数值映射到字符串键。

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

    输出:

    Initial Mappings are: {Geeks=20, Welcomes=25, You=30, 4=15}
    The set is: [Geeks=20, Welcomes=25, You=30, 4=15]

     
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