Java HashSet clear() Method

The clear() method of Java HashSet class is used to removes all of the elements from this set.

Syntax

Following is the declaration of clear() method:

Parameter

This method does not accept any parameter.

Returns

The clear() method does not return any value.

Exceptions:

Compatibility Version

Java 1.2 and above

Example 1

import java.util.*;
public class HashSetClearExample1 {
	public static void main(String[] args) {
		//Create hash set
	      HashSet<String> hset = new HashSet<String>();      
	      //Clear elements to hash set
	      hset.add("JTP"); 
	      hset.add("SSSIT");
	      hset.add("DFC");  
	      //Checking elements in hash set
	      System.out.println("Hash set Elements: "+ hset);
	      //Clear set values
	      hset.clear();
	      System.out.println("Hash set elements after clear: "+ hset); 
	      }
}

Test it Now

Output:

Hash set Elements: [DFC, SSSIT, JTP]
Hash set elements after clear: []

Example 2

import java.util.*;
public class HashSetClearExample2 {
	public static void main(String[] args) {
		//Create hash set
	      HashSet<Integer> hset = new HashSet<Integer>();      
	      //Clear 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);
	      //Clear set values
	      hset.clear();
	      System.out.println("Hash set elements after clear: "+ hset); 
	      }
}

Test it Now

Output:

Hash set Elements: [151, 121, 111]
Hash set elements after clear: []

Example 3

import java.util.*;
public class HashSetClearExample3 {
	public static void main(String[] args) {
		//Create HashSet object
            HashSet<String> hset1 = new HashSet<String>();                      
            //Add elements to HashSet
            hset1.add("Facebook");
		hset1.add("Twitter");
		hset1.add("Instagram");
		hset1.add("Google");       
            //Print the elements
		System.out.println("Size of the HashSet: "+hset1.size());
            System.out.println("Elements of the HashSet before clear:");      
            for(String val : hset1)
            {
                   System.out.println(val);
            }       
            hset1.clear();       
            //Printing the elements after clear operation
            System.out.println("Elements of the HashSet after clear:");
            System.out.println("Size of the hashset: "+hset1.size());
            for(String val : hset1)
            {
                   System.out.println(val);
            }
      }
}

Test it Now

Output:

Size of the HashSet: 4
Elements of the HashSet before clear:
Google
Twitter
Instagram
Facebook
Elements of the HashSet after clear:
Size of the hashset: 0

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