Check key existence in HashMap example

With this example we are going to demonstrate how to check a key existence in a HashMap. In short, to check if a key exists in a HashMap you should:

• Create a new HashMap.
• Populate the hashMap with elements, with the put(K key, V value) API method of HashMap.
• Invoke the containsKey(Object key) API method of the HashMap. The method returns true if the HashMap contains the specific key, otherwise it returns false.

Let’s take a look at the code snippet that follows:
 

package com.javacodegeeks.snippets.core;

import java.util.HashMap;
 
public class CheckKeyHashMap {
 
  public static void main(String[] args) {
 
    // Create a HashMap and populate it with elements
    HashMap hashMap = new HashMap();
    hashMap.put("key_1","value_1");
    hashMap.put("key_2","value_2");
    hashMap.put("key_3","value_3");
 
    // boolean containsKey(Object key) returns true if the HashMap contains the key, otherwise false.
    boolean exists = hashMap.containsKey("key_2");
    System.out.println("key_2 exists in HashMap ? : " + exists);
  }
}

Output:

key_2 exists in HashMap ? : true

 
This was an example of how to check a key existence in a HashMap in Java.