Skip to content
Related Articles

Related Articles

Improve Article
ConcurrentLinkedQueue poll() method in Java
  • Last Updated : 26 Nov, 2018

The poll() method of ConcurrentLinkedQueue is used to remove and return the head of this ConcurrentLinkedQueue. If the ConcurrentLinkedQueue is empty then this method will return null.

Syntax:

public E poll()

Returns: This method remove and returns the head of this ConcurrentLinkedQueue or null if this queue is empty.

Below programs illustrate poll() method of ConcurrentLinkedQueue:

Example 1:






// Java Program Demonstrate poll()
// method of ConcurrentLinkedQueue
  
import java.util.concurrent.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create an ConcurrentLinkedQueue
        ConcurrentLinkedQueue<Integer>
            queue = new ConcurrentLinkedQueue<Integer>();
  
        // Add Numbers to queue
        queue.add(4353);
        queue.add(7824);
        queue.add(78249);
        queue.add(8724);
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("ConcurrentLinkedQueue: " + queue);
  
        // apply poll()
        int response1 = queue.poll();
  
        // print after applying poll method
        System.out.println("Head: " + response1);
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("Current ConcurrentLinkedQueue: " + queue);
    }
}
Output:
ConcurrentLinkedQueue: [4353, 7824, 78249, 8724]
Head: 4353
Current ConcurrentLinkedQueue: [7824, 78249, 8724]

Example 2:




// Java Program Demonstrate poll()
// method of ConcurrentLinkedQueue
  
import java.util.concurrent.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create an ConcurrentLinkedQueue
        ConcurrentLinkedQueue<String>
            queue = new ConcurrentLinkedQueue<String>();
  
        // Add String to queue
        queue.add("Aman");
        queue.add("Amar");
        queue.add("Sanjeet");
        queue.add("Rabi");
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("ConcurrentLinkedQueue: " + queue);
  
        // apply poll() on queue
        String response1 = queue.poll();
  
        // print after applying poll method
        System.out.println("Head: " + response1);
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("Current ConcurrentLinkedQueue: " + queue);
  
        // apply poll() on queue more than one time
        queue.poll();
        queue.poll();
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("After 2 poll() applied\n"
                           + "ConcurrentLinkedQueue: " + queue);
    }
}
Output:
ConcurrentLinkedQueue: [Aman, Amar, Sanjeet, Rabi]
Head: Aman
Current ConcurrentLinkedQueue: [Amar, Sanjeet, Rabi]
After 2 poll() applied
ConcurrentLinkedQueue: [Rabi]

Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentLinkedQueue.html#poll–

Attention reader! Don’t stop learning now. Get hold of all the important Java Foundation and Collections concepts with the Fundamentals of Java and Java Collections Course at a student-friendly price and become industry ready. To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.




My Personal Notes arrow_drop_up
Recommended Articles
Page :