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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.

HashSet size example

In this example we shall show you how to get the HashSet size, that is the number of all the elements that the hashSet contains. To get the HashSet size one should perform the following steps:

  • Create a new HashSet.
  • Populate the hashSet with elements, using add(E e) API method of HashSet.
  • Invoke size() API method of HashSet. The method returns the int number of the elements existing in the HashSet.
  • We can remove an element from the hashSet, with remove(Object o) API method and then invoke size() method again, to check if the size is smaller after removing an element from the set,

as described in the code snippet below.

package com.javacodegeeks.snippets.core;
 
import java.util.HashSet;
 
public class HashSetSizeExample {
 
  public static void main(String[] args) {
 
    // Create a HashSet and populate it with elements
    HashSet hashSet = new HashSet();
    hashSet.add("element_1");
    hashSet.add("element_2");
    hashSet.add("element_3");
 
    // int size() method returns the number of elements in the HashSet   
    System.out.println("Size of HashSet : " + hashSet.size());
 
    // Remove one element from the HashSet using remove method
    hashSet.remove("element_2");
    System.out.println("Size of HashSet : " + hashSet.size());
  }
}

Output:

Size of HashSet : 3
Size of HashSet : 2

 
This was an example of how to get the HashSet size in Java.

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