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About Ilias Tsagklis

Ilias Tsagklis
Ilias is a software developer turned online entrepreneur. He is co-founder and Executive Editor at Java Code Geeks.

Get size of HashMap example

With this example we are going to demonstrate how to get the size of a HashMap, that is the number of key value pairs that the HashMap contains. In short, to the size of 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 size() API method of the HashMap. It will return the int number of key value pairs stored in the hashMap.

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

package com.javacodegeeks.snippets.core;

import java.util.HashMap;
 
public class SizeHashMap {
 
  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");
 
    // int size() operation returns the number of key value pairs stored in HashMap    
    System.out.println("Size of HashMap : " + hashMap.size());
  }
}

Output:

Size of HashMap : 3

 
This was an example of how to the size of a HashMap in Java.

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