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
Reference: https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/BlockingDeque.html#poll(long, %20java.util.concurrent.TimeUnit)
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