How to remove Elements from HashSet

In this post we will see various ways to remove elements from HashSet in java.

We can either use remove(Object o) OR an Iterator<E>

1. Example : Remove Elements from HashSet using remove()

package com.kscodes.sampleproject;

import java.util.HashSet;
import java.util.Set;

public class HashSetRemoveExample {

	public static void main(String[] args) {

		Set<String> hashSet = new HashSet<>();

		hashSet.add("Java");
		hashSet.add("Spring");
		hashSet.add("Hibernate");
		hashSet.add("JavaScript");

		System.out.println("HashSet before removing any element :: "
				+ hashSet.toString());

		// Now remove "Spring"
		hashSet.remove("Spring");

		System.out.println("HashSet after removing element :: "
				+ hashSet.toString());

	}
}

package com.kscodes.sampleproject;

import java.util.HashSet;

import java.util.Set;

public class HashSetRemoveExample {

public static void main(String[] args) {

Set<String> hashSet = new HashSet<>();

hashSet.add("Java");

hashSet.add("Spring");

hashSet.add("Hibernate");

hashSet.add("JavaScript");

System.out.println("HashSet before removing any element :: "

+ hashSet.toString());

// Now remove "Spring"

hashSet.remove("Spring");

System.out.println("HashSet after removing element :: "

+ hashSet.toString());

}

Output

HashSet before removing any element :: [Hibernate, Spring, JavaScript, Java]
HashSet after removing element :: [Hibernate, JavaScript, Java]

1 2	HashSet before removing any element :: [Hibernate, Spring, JavaScript, Java] HashSet after removing element :: [Hibernate, JavaScript, Java]

2. Example : Remove Elements from HashSet using Iterator

package com.kscodes.sampleproject;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

public class HashSetRemoveExample {

	public static void main(String[] args) {

		Set<String> hashSet = new HashSet<>();

		hashSet.add("Java");
		hashSet.add("Spring");
		hashSet.add("Hibernate");
		hashSet.add("JavaScript");

		System.out.println("HashSet before removing any element :: "
				+ hashSet.toString());

		Iterator<String> iterator = hashSet.iterator();
		while (iterator.hasNext()) {
			iterator.next();
			iterator.remove();
		}
		System.out.println("Removed All elements from HashSet :: "
				+ hashSet.toString());

	}
}

package com.kscodes.sampleproject;

import java.util.HashSet;

import java.util.Iterator;

import java.util.Set;

public class HashSetRemoveExample {

public static void main(String[] args) {

Set<String> hashSet = new HashSet<>();

hashSet.add("Java");

hashSet.add("Spring");

hashSet.add("Hibernate");

hashSet.add("JavaScript");

System.out.println("HashSet before removing any element :: "

+ hashSet.toString());

Iterator<String> iterator = hashSet.iterator();

while (iterator.hasNext()) {

iterator.next();

iterator.remove();

}

System.out.println("Removed All elements from HashSet :: "

+ hashSet.toString());

}

Output

HashSet before removing any element :: [Hibernate, Spring, JavaScript, Java]
Removed All elements from HashSet :: []

1 2	HashSet before removing any element :: [Hibernate, Spring, JavaScript, Java] Removed All elements from HashSet :: []

Reference

1. HashSet