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Java IdentityHashMap containsKey() Method with Example

IdentityHashMap Class containsKey() method: Here, we are going to learn about the containsKey() method of IdentityHashMap Class with its syntax and example.
Submitted by Preeti Jain, on March 06, 2020

IdentityHashMap Class containsKey() method

  • containsKey() method is available in java.util package.
  • containsKey() method is used to check whether the given object (key_ele) is a key element or not in this IdentityHashMap.
  • containsKey() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
  • containsKey() method does not throw an exception at the time of checking the existence of the given object.


    public boolean containsKey(Object key_ele);


  • Object key_ele – represents the object to be checked for key element (key_ele).

Return value:

The return type of the method is boolean, it returns true when the given object (key_ele) is a key element otherwise it returns false.


// Java program to demonstrate the example 
// of boolean containsKey(Object key_ele) method of IdentityHashMap 

import java.util.*;

public class ContainsKeyOfIdentityHashMap {
    public static void main(String[] args) {
        // Instantiates a IdentityHashMap object
        Map < Integer, String > map = new IdentityHashMap < Integer, String > ();

        // By using put() method is to add
        // key-value pairs in a IdentityHashMap
        map.put(10, "C");
        map.put(20, "C++");
        map.put(50, "JAVA");
        map.put(40, "PHP");
        map.put(30, "SFDC");

        // Display IdentityHashMap
        System.out.println("IdentityHashMap: " + map);

        // By using containsKey() method is
        // to check whether this map associates
        // any value for the given key element
        // of this IdentityHashMap

        boolean status = map.containsKey(30);

        System.out.print("map.containsKey(30): ");


IdentityHashMap: {20=C++, 40=PHP, 50=JAVA, 30=SFDC, 10=C}
map.containsKey(30): true


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