IdentityHashMap entrySet() Method in Java

Last Updated : 23 Jul, 2018

The java.util.IdentityHashMap.entrySet() method in Java is used to create a set out of the same elements contained in the map. It basically returns a set view of the identity hash map or we can create a new set and store the map elements into them. Syntax:

Identity_HashMap.entrySet()

Parameters: The method does not take any parameter. Return Value: The method returns a set having same elements as the map. Below programs illustrate the java.util.IdentityHashMap.entrySet() Method: Program 1: Mapping String Values to Integer Keys.

Java

// 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());
    }
}

Output:

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]

Program 2: Mapping Integer Values to String Keys.

Java

// 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());
    }
}

Output:

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

Note: The same operation can be performed with any type of Mappings with variation and combination of different data types.

IdentityHashMap equals() Method in Java

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