Java HashSet remove() Method

The remove() is a method of Java HashSet class which removes the specified element from this set if it is present.

Syntax

Following is the declaration of remove() method:

Parameter

Parameter	Description	Required/Optional
o	It is the object which will be removed to this set, if present.	Required

Returns

The remove() method returns true if the set contained the specified element.

Exceptions

Compatibility Version

Java 1.2 and above

Example 1

import java.util.*;
public class HashSetRemoveExample1 {
	public static void main(String[] args) {
		HashSet<String> set=new HashSet<String>();  
		set.add("Ravi");  
		set.add("Vijay");  
		set.add("Aman");  
		set.add("Ajay");  
		//Display HashSet
            System.out.println("HashSet: " + set); 
            //Remove elements using remove() method
            set.remove("Vijay");
            // Displaying the HashSet after removal
            System.out.println("HashSet after removing elements: " + set);
	}
}

Output:

HashSet: [Vijay, Ravi, Aman, Ajay]
HashSet after removing elements: [Ravi, Aman, Ajay]

Example 2

import java.util.*;
public class HashSetRemoveExample2 {
	public static void main(String[] args) {
		HashSet<Integer> hashSetObject = new HashSet <>();
		hashSetObject.add(45);
		hashSetObject.add(67);
		hashSetObject.add(98);
		hashSetObject.add(24);
		//Display HashSet
            System.out.println("HashSet: " + hashSetObject); 
            //Remove elements using remove() method
            hashSetObject.remove(98);
            hashSetObject.remove(24);
            //Displaying the HashSet after removal
          System.out.println("HashSet after removing elements: " + hashSetObject);
	}
}

Output:

HashSet: [98, 67, 24, 45]
HashSet after removing elements: [67, 45]

Example 3

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 HashSetRemoveExample3 {  
	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);  
		} 
		//Removing elements to HashSet
		set.remove(b2); 
		System.out.println("Books after remove method:");
		for(Book b:set){  
			System.out.println(b.id+" "+b.name+" "+b.author+" "+b.publisher+" "+b.quantity);  
		} 
	}  
}  

Output:

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

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