Java HashSet size() Method

The HashSet.size() method in Java is used to get the number of elements in a HashSet. This guide will cover the method’s usage, explain how it works, and provide examples to demonstrate its functionality.

Table of Contents

1. Introduction
2. size Method Syntax
3. Examples
   • Getting the Size of a HashSet
   • Checking Size After Adding and Removing Elements
4. Conclusion

Introduction

The HashSet.size() method is a member of the HashSet class in Java. It allows you to determine the number of elements currently stored in the HashSet. This method is useful for checking the size of the set at any point during its usage.

size Method Syntax

The syntax for the size method is as follows:

public int size()

• The method does not take any parameters.
• The method returns an int representing the number of elements in the HashSet.

Examples

Getting the Size of a HashSet

The size method can be used to get the number of elements in a HashSet.

Example

import java.util.HashSet;

public class SizeExample {
    public static void main(String[] args) {
        // Creating a HashSet of Strings
        HashSet<String> languages = new HashSet<>();

        // Adding elements to the HashSet
        languages.add("Java");
        languages.add("Python");
        languages.add("C");

        // Getting the size of the HashSet
        int size = languages.size();

        // Printing the size of the HashSet
        System.out.println("Size of HashSet: " + size);
    }
}

Output:

Size of HashSet: 3

Checking Size After Adding and Removing Elements

You can use the size method to check the size of the HashSet after performing operations like adding or removing elements.

Example

import java.util.HashSet;

public class SizeAfterOperationsExample {
    public static void main(String[] args) {
        // Creating a HashSet of Strings
        HashSet<String> languages = new HashSet<>();

        // Adding elements to the HashSet
        languages.add("Java");
        languages.add("Python");
        languages.add("C");

        // Printing the size of the HashSet
        System.out.println("Size of HashSet after adding elements: " + languages.size());

        // Removing an element from the HashSet
        languages.remove("Python");

        // Printing the size of the HashSet after removal
        System.out.println("Size of HashSet after removing an element: " + languages.size());

        // Adding more elements to the HashSet
        languages.add("C++");
        languages.add("JavaScript");

        // Printing the size of the HashSet after adding more elements
        System.out.println("Size of HashSet after adding more elements: " + languages.size());
    }
}

Output:

Size of HashSet after adding elements: 3
Size of HashSet after removing an element: 2
Size of HashSet after adding more elements: 4

Conclusion

The HashSet.size() method in Java provides a way to get the number of elements in a HashSet. By understanding how to use this method, you can efficiently manage the size of your collections in Java applications. This method is particularly useful for scenarios where you need to know the current size of the set to make decisions or perform operations based on the number of elements.