With this example we are going to demonstrate how to remove all elements from a HashSet. In short, to remove all elements from a HashSet you should:
- Create a new HashSet.
- Populate the hashSet with elements, using
add(E e)API method of HashSet. - Invoke
clear()API method of HashSet. The method removes all the elements from the set, so that the set is empty after this call.
We can call isEmpty() API method before and after clearing the HashSet, to check if the the set is empty or not.
Let’s take a look at the code snippet that follows:
package com.javacodegeeks.snippets.core;
import java.util.HashSet;
public class RemoveAllElementsHashSet {
public static void main(String[] args) {
// Create a HashSet and populate it with elements
HashSet hashSet = new HashSet();
hashSet.add("element_1");
hashSet.add("element_2");
hashSet.add("element_3");
// boolean isEmpty() method checks whether HashSet contains any elements or not
System.out.println("HashSet empty : " + hashSet.isEmpty());
// Remove all element from the HashSet using clear() or removeAll() methods
hashSet.clear();
System.out.println("HashSet empty : " + hashSet.isEmpty());
}
}
Output:
HashSet empty : false
HashSet empty : true
This was an example of how to remove all elements from a HashSet in Java.
