The HashSet.clear() method is present in the HashSet class inside the java.util package.
It clears all the elements from the HashSet, i.e., it empties the existing HashSet but does not delete the HashSet.
Let’s understand this with the help of an example. Suppose that a HashSet contains [1, 8, 5, 3 , 0]. Upon using the hashSet.clear() method, the HashSet becomes empty and when we display the elements of the HashSet, we get an empty array ([ ]).
The HashSet.clear() doesn’t accept any parameters.
The HashSet.clear() doesn’t return any value.
Let’s have a look at the code:
import java.io.*;import java.util.HashSet;class Main{public static void main(String args[]){HashSet<Integer> hash_set1 = new HashSet<Integer>();hash_set1.add(1);hash_set1.add(8);hash_set1.add(5);hash_set1.add(3);hash_set1.add(17);hash_set1.clear();System.out.println("hash_set1 after using HashSet.clear(): "+ hash_set1);}}
In lines 1 and 2, we import the required packages and classes.
In line 4, we make the Main class.
In line 6, we make the main() function.
In line 8, we declare a HashSet of the integer type i.e., hash_set1.
From lines 9 to 13, we add the elements into the HashSet by using the HashSet.add() method.
In line 14, we use the HashSet.clear() method to empty the Hashset.
In line 16, we display the HashSet after using the HashSet.clear() method with a message.