IdentityHashMap containsKey() Method in Java

The java.util.IdentityHashMap.containsKey() method is used to check whether a particular key is being mapped into the IdentityHashMap or not. It takes the key element as a parameter and returns True if that element is mapped in the map.

Syntax:

Identity_HashMap.containsKey(key_element)

Parameters: The method takes just one parameter key_element that refers to the key whose mapping is supposed to be checked inside a map.

Return Value: The method returns boolean true if the presence of the key is detected else false .

Below programs are used to illustrate the working of java.util.IdentityHashMap.containsKey() Method:
Program 1: Mapping String Values to Integer Keys.

// Java code to illustrate the containsKey() 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);

        // Checking for the key_element '20'
        System.out.println("Is the key '20' present? " +
                           identity_hash.containsKey(20));

        // Checking for the key_element '5'
        System.out.println("Is the key '5' present? " +
                            identity_hash.containsKey(5));
    }
}

Output:

Initial Mappings are: {10=Geeks, 30=You, 20=Geeks, 25=Welcomes, 15=4}
Is the key '20' present? true
Is the key '5' present? false

Program 2: Mapping Integer Values to String Keys.

// Java code to illustrate the containsKey() 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);

        // Checking for the key_element 'Welcomes'
        System.out.println("Is the key 'Welcomes' present? " +
                        identity_hash.containsKey("Welcomes"));

        // Checking for the key_element 'World'
        System.out.println("Is the key 'World' present? " +
                           identity_hash.containsKey("World"));
    }
}

Output:

Initial Mappings are: {Geeks=20, Welcomes=25, You=30, 4=15}
Is the key 'Welcomes' present? true
Is the key 'World' present? false

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