An Deque interface.
ArrayDequecan be used both as a stack or queue.Nullelements are prohibited.
offerFirst methodThe offerFirst method can be used to add an element to the front of the ArrayDeque object.
public boolean offerFirst(E e)
The offerFirst method takes the element to be added to the deque as a parameter. This method throws NullPointerException if the argument is null.
The offerFirst method returns true if the element is added to the deque. Otherwise, false is returned.
The code below demonstrates how to use the offerFirst method.
import java.util.ArrayDeque;class OfferFirst {public static void main( String args[] ) {ArrayDeque<String> arrayDeque = new ArrayDeque<>();arrayDeque.offerFirst("2");System.out.println("The arrayDeque is " + arrayDeque);arrayDeque.offerFirst("1");System.out.println("The arrayDeque is " + arrayDeque);}}
In the code above:
In line 1, we imported the ArrayDeque class.
In line 4, we created an ArrayDeque
object with the name arrayDeque.
In line 5, we used the offerFirst method of the arrayDeque object to add an element ("2") to the beginning of the deque. Then, we printed it.
In line 8, we used the offerFirst method to add an element ("1") to the beginning of the deque. Then, we printed it.