The java.util.ArrayDeque.offerFirst(E e) method inserts the specified element E at the front of this deque.
Following is the declaration for java.util.ArrayDeque.offerFirst() method
public boolean offerFirst(E e)
e − The element to be added at the front.
This method returns true if the element was added to this deque, else false.
NullPointerException − if the specified element is null.
The following example shows the usage of java.util.ArrayDeque.offerFirst() method.
package com.tutorialspoint; import java.util.ArrayDeque; import java.util.Deque; public class ArrayDequeDemo { public static void main(String[] args) { // create an empty array deque with an initial capacity Deque<Integer> deque = new ArrayDeque<Integer>(8); // use add() method to add elements in the deque deque.add(25); deque.add(30); deque.add(20); deque.add(18); // this will insert 10 at the front deque.offerFirst(10); // printing all the elements available in deque for (Integer number : deque) { System.out.println("Number = " + number); } } }
Let us compile and run the above program, this will produce the following result −
Number = 10 Number = 25 Number = 30 Number = 20 Number = 18