ArrayDeque addFirst() Method in Java
Last Updated :
10 Dec, 2018
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The java.util.ArrayDeque.addFirst(Object element) method in Java is used to insert a specific element at the front of this deque.
Syntax:
Array_Deque.addFirst(Object element)
Parameters: The parameter element is of the type ArrayDeque and refers to the element to be added.
Return Value: The function does not return any value.
Exceptions: The method throws NullPointerException if the passed parameter is NULL.
Below programs illustrate the Java.util.ArrayDeque.addFirst() method:
Program 1:
// Java code to illustrate addFirst() 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("ArrayDeque: " + de_que); // Adding elements at front de_que.addFirst(40); de_que.addFirst(50); de_que.addFirst(60); de_que.addFirst(70); // Displaying the ArrayDeque System.out.println("ArrayDeque_front_addition: " + de_que); // Adding elements using add() de_que.add(1); de_que.add(2); de_que.add(3); // Displaying the final ArrayDeque System.out.println("Final ArrayDeque: " + de_que); } } |
Output:
ArrayDeque: [10, 15, 30, 20, 5] ArrayDeque_front_addition: [70, 60, 50, 40, 10, 15, 30, 20, 5] Final ArrayDeque: [70, 60, 50, 40, 10, 15, 30, 20, 5, 1, 2, 3]
Program 2:
// Java code to illustrate addFirst() 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("ArrayDeque: " + de_que); // Adding elements at front de_que.addFirst("GFG"); de_que.addFirst("World"); de_que.addFirst("Hello"); // Displaying the ArrayDeque System.out.println("ArrayDeque_front_addition: " + de_que); // Adding elements using add() de_que.add("Coding"); de_que.add("At"); de_que.add("BEST"); // Displaying the final ArrayDeque System.out.println("Final ArrayDeque: " + de_que); } } |
Output:
ArrayDeque: [Welcome, To, Geeks, 4, Geeks] ArrayDeque_front_addition: [Hello, World, GFG, Welcome, To, Geeks, 4, Geeks] Final ArrayDeque: [Hello, World, GFG, Welcome, To, Geeks, 4, Geeks, Coding, At, BEST]
