Java HashSet add() Method

The add() is a method of Java HashSet class which adds the specified element to this set if this set contains no element. If it is already contain the element, the call leaves the set unchanged and returns false.

Syntax

Following is the declaration of add() method:

Parameter

Parameter	Description	Required/Optional
e	It is the element which will be added to this set.	Required

Returns

The add() method returns true if this set did not already contain the specified element.

Exceptions

Compatibility Version

Java 1.2 and above

Example 1

import java.util.*;
public class HashSetAddExample1 {
	public static void main(String[] args) {
		HashSet<String> set=new HashSet<String>();  
		set.add("Ravi");  
		set.add("Vijay");  
		set.add("Ravi");  
		set.add("Ajay");  
		//Traversing elements  
		Iterator<String> itr=set.iterator();  
		while(itr.hasNext()){  
		   System.out.println(itr.next());  
		}  
	}
}

Test it Now

Output:

Vijay
Ravi
Ajay

Example 2

import java.util.*;
public class HashSetAddExample2 {
	public static void main(String[] args) {
		//Create hash set
	      HashSet<Integer> hset = new HashSet<Integer>();      
	      //Add elements to hash set
	      hset.add(121); 
	      hset.add(111);
	      hset.add(151);  
	      //Checking elements in hash set
	      System.out.println("Hash set Elements: "+ hset);
	      }
}

Test it Now

Output:

Hash set Elements: [151, 121, 111]

Example 3

import java.util.*;
public class HashSetAddExample3 {
	public static void main(String[] args) {
		//Create HashSet object
		HashSet<String> hashset1 = new HashSet<String>();				
		//Adding elements to HashSet
		hashset1.add("Facebook");
		hashset1.add("Twitter");
		hashset1.add("Instagram");
		boolean flag = hashset1.add("Google");				
		System.out.println("Is the insertion successful?? - "+flag);		
		//Print the elements of the HashSet
		System.out.println("Elements of the HashSet:");
		for(String val : hashset1)
		{
			System.out.println(val);
		}
	}
}

Test it Now

Output:

Is the insertion successful?? - true
Elements of the HashSet:
Google
Twitter
Instagram
Facebook

Example 4

import java.util.*;  
class Book {  
	int id;  
	String name,author,publisher;  
	int quantity;  
	public Book(int id, String name, String author, String publisher, int quantity) {  
		this.id = id;  
		this.name = name;  
		this.author = author;  
		this.publisher = publisher;  
		this.quantity = quantity;  
	}  
}  
public class HashSetAddExample4 {  
	public static void main(String[] args) {  
		HashSet<Book> set=new HashSet<Book>();  
		//Creating Books  
		Book b1=new Book(101,"Let us C","Yashwant Kanetkar","BPB",8);  
		Book b2=new Book(102,"Data Communications & Networking","Forouzan","Mc Graw Hill",4);  
		Book b3=new Book(103,"Operating System","Galvin","Wiley",6);  
		//Adding Books to HashSet  
		set.add(b1);  
		set.add(b2);  
		set.add(b3);  
		//Traversing HashSet  
		for(Book b:set){  
			System.out.println(b.id+" "+b.name+" "+b.author+" "+b.publisher+" "+b.quantity);  
		}  
	}  
}  

Test it Now

Output:

103 Operating System Galvin Wiley 6
102 Data Communications & Networking Forouzan Mc Graw Hill 4
101 Let us C Yashwant Kanetkar BPB 8

Next TopicHashSet clear() Method

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Java HashSet add() Method

Syntax

Parameter

Returns

Exceptions

Compatibility Version

Example 1

Example 2

Example 3

Example 4

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