How to Empty a HashSet in Java
In Java, a HashSet is a collection that contains no duplicate elements. It is a Set implementation based on a hash table. If you need to remove all elements from a HashSet, there are several methods you can use. In this article, we will discuss different ways to empty a HashSet in Java.
1. Using the clear() method
The most straightforward way to empty a HashSet is by using the clear() method. This method removes all of the elements from the set. Here is an example:
“`java
import java.util.HashSet;
public class Main {
public static void main(String[] args) {
HashSet
hashSet.add(“Apple”);
hashSet.add(“Banana”);
hashSet.add(“Cherry”);
System.out.println(“HashSet before clearing: ” + hashSet);
hashSet.clear();
System.out.println(“HashSet after clearing: ” + hashSet);
}
}
“`
Output:
“`
HashSet before clearing: [Apple, Banana, Cherry]
HashSet after clearing: []
“`
2. Using a loop
Another way to empty a HashSet is by using a loop to remove each element individually. This can be useful if you want to perform some action on each element before removing it. Here is an example:
“`java
import java.util.HashSet;
public class Main {
public static void main(String[] args) {
HashSet
hashSet.add(“Apple”);
hashSet.add(“Banana”);
hashSet.add(“Cherry”);
System.out.println(“HashSet before clearing: ” + hashSet);
while (!hashSet.isEmpty()) {
hashSet.remove(hashSet.iterator().next());
}
System.out.println(“HashSet after clearing: ” + hashSet);
}
}
“`
Output:
“`
HashSet before clearing: [Apple, Banana, Cherry]
HashSet after clearing: []
“`
3. Using a new HashSet
You can also create a new HashSet object and assign it to the existing HashSet variable. This will effectively remove all elements from the original HashSet. Here is an example:
“`java
import java.util.HashSet;
public class Main {
public static void main(String[] args) {
HashSet
hashSet.add(“Apple”);
hashSet.add(“Banana”);
hashSet.add(“Cherry”);
System.out.println(“HashSet before clearing: ” + hashSet);
hashSet = new HashSet<>();
System.out.println(“HashSet after clearing: ” + hashSet);
}
}
“`
Output:
“`
HashSet before clearing: [Apple, Banana, Cherry]
HashSet after clearing: []
“`
In conclusion, there are multiple ways to empty a HashSet in Java. The clear() method is the most straightforward approach, while using a loop or creating a new HashSet can be useful in certain scenarios. Choose the method that best suits your needs and preferences.
