Collection clear() method in Java with Examples
Last Updated : 16 Feb, 2024
The collection clear() method of Java Collection Interface clears the Collection upon which it is called. After this method is called, the collection will be empty as it removes all the elements from the collection.
This method does not take any parameter and does not return any value.
Example:
Java // Java program to demonstrate the // usage of clear() method in ArrayList import java.util.ArrayList; import java.util.Arrays; public class ClearMethodExample { public static void main(String[] args) { // Create an ArrayList and initialize it with some elements ArrayList<String> list = new ArrayList<>(Arrays.asList("1", "2", "3", "4")); // Display the list before clearing System.out.println("List before clearing: " + list); // Clear the list list.clear(); // Display the list after clearing System.out.println("List after clearing: " + list); } } Output:
List before clearing: [1, 2, 3, 4]
List after clearing: []
Syntax
Collection.clear()
Parameters:
- This method does not accept any parameter
Returns:
- This method does not return any value.
Exceptions:
- UnsupportedOperationException: if the add operation is not supported by this collection
Collection clear() Method Examples
Let's see some examples of how to use the collection clear() method in Java.
Example 1:
How to remove all elements from a collection using collection clear() Method
Java import java.io.*; import java.util.*; public class GFG { public static void main(String args[]) { // creating an empty LinkedList Collection<String> list = new LinkedList<>(); // use add() method to add elements in the list list.add("Geeks"); list.add("for"); list.add("Geeks"); // Output the present list System.out.println("The list is: " + list); // Clearing the LinkedList list.clear(); // printing the new list System.out.println("The new List is: " + list); } } OutputThe list is: [Geeks, for, Geeks] The new List is: []
Example 2:
Using the clear() method on ArrayDeque to remove its elements.
Java // Java code to illustrate clear() method import java.util.*; public class ArrayDequeDemo { public static void main(String args[]) { // Creating an empty ArrayDeque Collection<String> de_que = new ArrayDeque<String>(); // Use add() method to add elements into the Deque de_que.add("Welcome"); de_que.add("To"); de_que.add("Geeks"); de_que.add("4"); de_que.add("Geeks"); // Displaying the ArrayDeque System.out.println("ArrayDeque: " + de_que); // Clearing the ArrayDeque de_que.clear(); // printing the new ArrayDeque System.out.println("The new ArrayDeque is: " + de_que); } } OutputArrayDeque: [Welcome, To, Geeks, 4, Geeks] The new ArrayDeque is: []
Example 3:
Using the clear() method on ArrayList
Java // Java code to illustrate clear() method import java.io.*; import java.util.*; public class ArrayListDemo { public static void main(String[] args) { // create an empty array list with an initial capacity Collection<Integer> arrlist = new ArrayList<Integer>(5); // use add() method to add elements in the list arrlist.add(15); arrlist.add(20); arrlist.add(25); // prints all the elements available in list System.out.println("ArrayList: " + arrlist); // Clearing the ArrayList arrlist.clear(); // printing the new ArrayList System.out.println("The new ArrayList is: " + arrlist); } } OutputArrayList: [15, 20, 25] The new ArrayList is: []
Reference: Official Oracle Documents
Whether you are a beginner starting Java programming or an experienced looking to brush up on your Java skills, this tutorial will provide you with a deep understanding of the collection clear function and its uses in Java.
The clear method in Java is a fundamental function for collection manipulation. With this guide, you can easily remove all elements of a collection using the clear function.
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