The Java.util.ArrayDeque.offerFirst(Object element) method in Java is used to add a specific element at the front of the Deque. The function is similar to the addFirst() method of ArrayDeque in Java.
Syntax:
Array_Deque.offerFirst(Object element)
Parameters: The parameter element is of the type ArrayDeque and refers to the element to be added at the front of the Deque.
Return Value: The function returns True if the element is successfully added into the deque else it returns false.
Exceptions: The method throws NullPointerException if the passed parameter is NULL.
Below programs illustrate the Java.util.ArrayDeque.offerFirst() method:
Program 1: Adding String elements into the Deque.
// Java code to illustrate offerFirst()import java.util.*;  public class ArrayDequeDemo {    public static void main(String args[])    {        // Creating an empty ArrayDeque        Deque<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("Initial Deque: " + de_que);          // Using offerFirst() to add elements        de_que.offerFirst("World");        de_que.offerFirst("Hello");          // Displaying the ArrayDeque        System.out.println("Final Deque: " + de_que);    }} |
Output:
Initial Deque: [Welcome, To, Geeks, 4, Geeks] Final Deque: [Hello, World, Welcome, To, Geeks, 4, Geeks]
Program 2: Adding Integer elements into the Deque.
// Java code to illustrate offerFirst()import java.util.*;  public class ArrayDequeDemo {    public static void main(String args[])    {        // Creating an empty ArrayDeque        Deque<Integer> de_que = new ArrayDeque<Integer>();          // Use add() method to add elements into the Deque        de_que.add(10);        de_que.add(15);        de_que.add(30);        de_que.add(20);        de_que.add(5);          // Displaying the ArrayDeque        System.out.println("Initial Deque: " + de_que);          // Using offerFirst() to add elements        de_que.offerFirst(1658);        de_que.offerFirst(2458);          // Displaying the ArrayDeque        System.out.println("Final Deque: " + de_que);    }} |
Output:
Initial Deque: [10, 15, 30, 20, 5] Final Deque: [2458, 1658, 10, 15, 30, 20, 5]
