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/* 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 */ |
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