BlockingDeque poll() method in Java with examples
The poll() method of BlockingDeque 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.
Note: The poll() method of BlockingDeque has been inherited from the LinkedBlockingDeque class in Java.
Below programs illustrate poll() method of BlockingDeque:
Program 1:
// Java Program Demonstrate poll()// method of BlockingDeque  import java.util.concurrent.LinkedBlockingDeque;import java.util.concurrent.BlockingDeque import java.util.*;  public class GFG {    public static void main(String[] args)      {          // create object of BlockingDeque        BlockingDeque<Integer> BD            = new LinkedBlockingDeque<Integer>();          // Add numbers to end of BlockingDeque        BD.add(7855642);        BD.add(35658786);        BD.add(5278367);        BD.add(74381793);          // Print the queue        System.out.println("Blocking Deque: " + BD);          System.out.println("Front element in Deque: " + BD.poll());          // One element is deleted as poll was called        System.out.println("Blocking Deque: " + BD);    }} |
Output:
Blocking Deque: [7855642, 35658786, 5278367, 74381793] Front element in Deque: 7855642 Blocking Deque: [35658786, 5278367, 74381793]
Program 2:
// Java Program Demonstrate poll()// method of BlockingDeque// when Deque is empty  import java.util.concurrent.LinkedBlockingDeque;import java.util.concurrent.BlockingDeque import java.util.*;  public class GFG {    public static void main(String[] args)      {          // create object of BlockingDeque        BlockingDeque<Integer> BD            = new LinkedBlockingDeque<Integer>();          // Add numbers to end of BlockingDeque        BD.add(7855642);        BD.add(35658786);        BD.add(5278367);        BD.add(74381793);          // Print the queue        System.out.println("Blocking Deque: " + BD);          // empty deque        BD.clear();          System.out.println("Front element in Deque: " + BD.poll());    }} |
Output:
Blocking Deque: [7855642, 35658786, 5278367, 74381793] Front element in Deque: null
