The java.util.concurrent.ConcurrentLinkedDeque.pollFirst() is an in-built method in Java which retrieves the first element of this deque and removes it. If the deque is empty, the method returns NULL.
Syntax:
Conn_Linked_Deque.pollFirst()
Parameters: This function does not accepts any parameter.
Return Values: The function returns the first element of this deque. If this deque is empty, the function returns NULL.
Below program illustrates the use of pollFirst() method:
Program 1: This program involves deque with Integer elements.
// Java Program Demonstrate pollFirst() // method of ConcurrentLinkedDeque import java.util.concurrent.*; class ConcurrentLinkedDequeDemo { public static void main(String[] args) { ConcurrentLinkedDeque<Integer> cld = new ConcurrentLinkedDeque<Integer>(); cld.addFirst(12); cld.addFirst(70); cld.addFirst(1009); cld.addFirst(475); // Displaying the existing LinkedDeque System.out.println("Elements in" + "the LinkedDeque: " + cld); // Display and remove the first element System.out.println("Element removed : " + cld.pollFirst()); // Displaying the elements System.out.println("Elements in" + "the LinkedDeque: " + cld); }} |
Output:
Elements inthe LinkedDeque: [475, 1009, 70, 12] Element removed : 475 Elements inthe LinkedDeque: [1009, 70, 12]
Program 2: This program involves deque with String elements.
// Java Program Demonstrate pollFirst() // method of ConcurrentLinkedDeque import java.util.concurrent.*; class ConcurrentLinkedDequeDemo { public static void main(String[] args) { ConcurrentLinkedDeque<String> cld = new ConcurrentLinkedDeque<String>(); cld.addFirst("GFG"); cld.addFirst("Geeks"); cld.addFirst("Gfg"); cld.addFirst("Geeks"); // Displaying the existing LinkedDeque System.out.println("Elements in" + "the LinkedDeque: " + cld); // Display and remove the First element System.out.println("Element removed : " + cld.pollFirst()); // Displaying the elements System.out.println("Elements in" + "the LinkedDeque: " + cld); }} |
Output:
Elements inthe LinkedDeque: [Geeks, Gfg, Geeks, GFG] Element removed : Geeks Elements inthe LinkedDeque: [Gfg, Geeks, GFG]
