The java.util.concurrent.LinkedTransferQueue.poll() method is an in-built function in Java which retrieves and remove the head of the queue if the queue is non-empty.
Syntax:
LinkedTransferQueue.poll()
Parameters: The function does not accept any parameter.
Return Value: The function returns the head of the queue if the queue is non-empty, otherwise it returns null.
Below programs illustrate the LinkedTransferQueue.poll() method:
Program 1:
/* Java Program Demonstrate poll()   method of LinkedTransferQueue */  import java.util.concurrent.LinkedTransferQueue;  class LinkedTransferQueuePollExample1 {    public static void main(String[] args)    {        // Initializing the queue        LinkedTransferQueue<Character> queue =                        new LinkedTransferQueue<Character>();          // Adding elements to this queue        for (char ch = 'A'; ch <= 'Z'; ch++) {            queue.add(ch);        }          // Printing the head of the queue        System.out.println("The head of the queue is "                                            + queue.poll());          // Printing remaining elements of the queue        System.out.println("The elements in the queue :");        for (Character i : queue)            System.out.print(i + " ");    }} |
Output:
The head of the queue is A The elements in the queue : B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Program 2:
/* Java Program Demonstrate poll()   method of LinkedTransferQueue */  import java.util.concurrent.LinkedTransferQueue;  class LinkedTransferQueuePollExample2 {    public static void main(String[] args)    {        // Initializing the queue        LinkedTransferQueue<Integer> queue =                      new LinkedTransferQueue<Integer>();          // Adding elements to this queue        for (int i = 10; i <= 50; i += 10)            queue.add(i);          // Printing the head of the queue        System.out.println("The head of the queue is "                                            + queue.poll());          // Printing remaining elements of the queue        System.out.println("The elements in the queue :");        for (Integer i : queue)            System.out.print(i + " ");    }} |
Output:
The head of the queue is 10 The elements in the queue : 20 30 40 50
Reference: https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/LinkedTransferQueue.html#poll()
