Java HashSet iterator() Method

Last Updated : 23 Jan, 2025

The HashSet iterator() method in Java is used to return an iterator that can be used to iterate over the elements in a HashSet. HashSet does not maintain any specific order of its elements, so the elements are returned in random order when iterated over. The iterator() method provides a way to traverse the elements in the set, allowing you to access them one by one.

Example 1: Iterating over a HashSet of Integers

Java

// Java Program to demonstrates the working of  // iterator() over a HashSet of Integers import java.util.HashSet; import java.util.Iterator;  public class Geeks {     public static void main(String[] args)     {         // Create a HashSet         HashSet<Integer> hs = new HashSet<>();          // Add elements to the HashSet         hs.add(10);         hs.add(20);         hs.add(30);          // Get the iterator         Iterator<Integer> i = hs.iterator();          // Traverse the HashSet using the iterator         System.out.println("HashSet: " + hs);         System.out.print("The iterator values are: ");         while (i.hasNext()) {             System.out.print(i.next() + " ");         }     } }

Output

HashSet: [20, 10, 30] The iterator values are: 20 10 30

Note: The order of elements in a HashSet is not guaranteed and can vary each time the program runs, as shown in the output.

Syntax of HashSet iterator() Method

public Iterator<E> iterator();

Return Type: This method returns an Iterator object to traverse the elements in the collection one by one.

Example 2: Iterating over a HashSet of Custom Objects

In this example, we will demonstrate how to store custom object “Employee” in a HashSet and iterate through them using an iterator.

Java

// Java program to demonstrates the use of HashSet to store // of HashSet to store custom objects and the traversal  // of these objects using an iterator import java.util.HashSet; import java.util.Iterator;  public class Geeks {     public static void main(String args[])     {          // create hash set         HashSet<Employee> hs = new HashSet<>();          hs.add(new Employee(10, "Geek1"));         hs.add(new Employee(2, "Geek20"));         hs.add(new Employee(35, "Geek5"));          // create an iterator         Iterator<Employee> i = hs.iterator();          // iterate through the HashSet and          // print each employee object         while (i.hasNext()) {             System.out.println("Value: " + i.next() + " ");         }     } }  // create a class representing Employee class Employee {     int id;     String name;      Employee(int id, String name)     {         this.id = id;         this.name = name;     }     // Override the toString() to provide the string     // representation of the Employee object     @Override public String toString()     {         return "[ " + this.id + ", " + this.name             + " ]";     } }

Output

Value: [ 35, Geek5 ]  Value: [ 10, Geek1 ]  Value: [ 2, Geek20 ]

Java HashSet isEmpty() Method

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