ConcurrentLinkedDeque poll() method in Java with Example

The poll() method of ConcurrentLinkedDeque returns the front element in the Deque container and deletes it. It returns null if the container is empty.

Syntax:

public E poll()

Parameters: This method does not accept any parameters.

Returns: This method returns front element of the Deque container if the container is not empty and deletes it. It returns null if the container is empty.

Below programs illustrate poll() method of ConcurrentLinkedDeque:

Program 1:

// Java Program Demonstrate poll()
// method of ConcurrentLinkedDeque

import java.util.concurrent.ConcurrentLinkedDeque;
import java.util.*;

public class GFG {
    public static void main(String[] args)

    {

        // create object of ConcurrentLinkedDeque
        ConcurrentLinkedDeque<Integer> CLD
            = new ConcurrentLinkedDeque<Integer>();

        // Add numbers to end of ConcurrentLinkedDeque
        CLD.add(7855642);
        CLD.add(35658786);
        CLD.add(5278367);
        CLD.add(74381793);

        // Print the queue
        System.out.println("ConcurrentLinkedDeque: "
                           + CLD);

        System.out.println("Front element in Deque: "
                           + CLD.poll());

        // One element is deleted as poll was called
        System.out.println("ConcurrentLinkedDeque: "
                           + CLD);
    }
}

Output:

ConcurrentLinkedDeque: [7855642, 35658786, 5278367, 74381793]
Front element in Deque: 7855642
ConcurrentLinkedDeque: [35658786, 5278367, 74381793]

Program 2:

// Java Program Demonstrate poll()
// method of ConcurrentLinkedDeque
// when Deque is empty

import java.util.concurrent.ConcurrentLinkedDeque;
import java.util.*;

public class GFG {
    public static void main(String[] args)

    {

        // create object of ConcurrentLinkedDeque
        ConcurrentLinkedDeque<Integer> CLD
            = new ConcurrentLinkedDeque<Integer>();

        // Add numbers to end of ConcurrentLinkedDeque
        CLD.add(7855642);
        CLD.add(35658786);
        CLD.add(5278367);
        CLD.add(74381793);

        // Print the queue
        System.out.println("ConcurrentLinkedDeque: "
                           + CLD);

        // empty deque
        CLD.clear();

        System.out.println("Front element in Deque: "
                           + CLD.poll());
    }
}

Output:

ConcurrentLinkedDeque: [7855642, 35658786, 5278367, 74381793]
Front element in Deque: null