Collection clear() method in Java with Examples
The clear() of java.util.Collection interface is used to clear the Collection upon which it is called. This method does not take any parameter and does not returns any value.
Syntax:
Collection.clear()
Parameters: This method do not accept any parameter
Return Value: This method does not return any value.
Exceptions: This method throws following exceptions:
- UnsupportedOperationException: if the add operation is not supported by this collection
Below examples illustrate the Collection clear() method:
Example 1: Using LinkedList Class
// Java code to illustrate boolean clear() method import java.io.*;import java.util.*; public class GFG { public static void main(String args[]) { // creating an empty LinkedList Collection<String> list = new LinkedList<String>(); // 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); }} |
Output:
The list is: [Geeks, for, Geeks] The new List is: []
Example 2: Using ArrayDeque Class
// 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); }} |
Output:
ArrayDeque: [Welcome, To, Geeks, 4, Geeks] The new ArrayDeque is: []
Example 3: Using ArrayList Class
// 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); }} |
Output:
ArrayList: [15, 20, 25] The new ArrayList is: []
Reference: https://docs.oracle.com/javase/9/docs/api/java/util/Collection.html#clear–
