/*
Remove all elements from Java HashSet example
This Java Example shows how to remove all elements contained in Java HashSet
or clear HashSet object using clear or removeAll methods. It also shows how
to check whether HashSet object is empty or not using isEmpty method.
*/
import java.util.HashSet;
public class RemoveAllElementsFromHashSetExample {
public static void main(String[] args) {
//create object of HashSet
HashSet hSet = new HashSet();
//add elements to HashSet object
hSet.add(new Integer("1"));
hSet.add(new Integer("2"));
hSet.add(new Integer("3"));
System.out.println("HashSet before removal : " + hSet);
/*
To remove all elements from Java HashSet or to clear HashSet object use,
void clear() method.
This method removes all elements from HashSet.
*/
hSet.clear();
System.out.println("HashSet after removal : " + hSet);
/*
To check whether HashSet contains any elements or not use
boolean isEmpty() method.
This method returns true if the HashSet does not contains any elements
otherwise false.
*/
System.out.println("Is HashSet empty ? " + hSet.isEmpty());
/*
Please note that removeAll method of Java HashSet class can also be
used to remove all elements from HashSet object.
*/
}
}
/*
Output would be
HashSet before removal : [3, 2, 1]
HashSet after removal : []
Is HashSet empty ? true
*/
