Java IdentityHashMap entrySet()方法

Java中的java.util.IdentityHashMap.entrySet()方法是用来从地图中包含的相同元素中创建一个集合。它基本上返回一个身份哈希图的集合视图，或者我们可以创建一个新的集合并将地图元素存储到其中。

语法

Identity_HashMap.entrySet()

参数： 该方法不接受任何参数。

返回值： 该方法返回一个具有与地图相同元素的集合。

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]

注意： 同样的操作可以通过不同数据类型的变化和组合对任何类型的Mapping进行操作。