ArrayBlockingQueue poll() Method in Java
Last Updated :
11 Jul, 2025
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ArrayBlockingQueue is bounded, blocking queue that stores the elements internally backed by an array.
- ArrayBlockingQueue class is a member of the Java Collections Framework.
- Bounded means it will have a fixed size, you can not store number the elements more than the capacity of the queue.
- The queue also follows FIFO (first-in-first-out) rule for storing and removing elements from the queue.
- If you try to put an element into a full queue or to take an element from an empty queue then the queue will block you.
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The poll() method retrieves and removes element from head of this queue.If queue is empty then method will return null.
Syntax:
public E poll()
Return Value: The method returns the element from the head of this queue, or null if this queue is empty. Below programs illustrate poll() method of ArrayBlockingQueue. Program 1:Java /* *Program Demonstrate poll() method of ArrayBlockingQueue. */ import java.util.concurrent.ArrayBlockingQueue; public class GFG { public static void main(String[] args) { // define capacity of ArrayBlockingQueue int capacity = 5; // create object of ArrayBlockingQueue ArrayBlockingQueue<Integer> queue = new ArrayBlockingQueue<Integer>(capacity); // Add elements to ArrayBlockingQueue queue.offer(423); queue.offer(233); queue.offer(356); // print elements System.out.println("Queue Contains" + queue); // try to poll elements System.out.println("Removing From head: " + queue.poll()); System.out.println("Queue Contains" + queue); System.out.println("Removing From head: " + queue.poll()); System.out.println("Queue Contains" + queue); System.out.println("Removing From head: " + queue.poll()); System.out.println("Queue Contains" + queue); System.out.println("Removing From head: " + queue.poll()); System.out.println("Queue Contains" + queue); } }
Output:Program 2:Queue Contains[423, 233, 356] Removing From head: 423 Queue Contains[233, 356] Removing From head: 233 Queue Contains[356] Removing From head: 356 Queue Contains[] Removing From head: null Queue Contains[]
Java /* * Program Demonstrate poll() method of ArrayBlockingQueue. */ import java.util.concurrent.ArrayBlockingQueue; public class GFG { // Create a User Object with name and age as an attribute public class User { public String name; public String age; User(String name, String age) { this.name = name; this.age = age; } } // Main Method public static void main(String[] args) { GFG gfg = new GFG(); gfg.pollMethodExample(); } // Method to give example of poll function public void pollMethodExample() { // Define the capacity of ArrayBlockingQueue int capacity = 5; // Create object of ArrayBlockingQueue ArrayBlockingQueue<User> queue = new ArrayBlockingQueue<User>(capacity); // Create user objects User user1 = new User("Aman", "24"); User user3 = new User("Sanjeet", "25"); // Add Objects to ArrayBlockingQueue queue.offer(user1); queue.offer(user3); // Poll users from queue User user = queue.poll(); System.out.println("removing user having name = " + user.name); user = queue.poll(); System.out.println("removing user having name = " + user.name); // Now queue is empty // Try to remove it will return null user = queue.poll(); System.out.println("removing user having name = " + user); } }
Output:removing user having name = Aman removing user having name = Sanjeet removing user having name = null
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The poll(long timeout, TimeUnit unit) method retrieves and removes element from head of this queue. If the queue is empty then it will, wait till a specified time for an element to become available.
Syntax:
public E poll(long timeout, TimeUnit unit) throws InterruptedException
Parameters: The method takes two parameters:- timeout (long) - how long to wait before giving up, in units of unit.
- unit (TimeUnit)- a TimeUnit determining how to interpret the timeout parameter.
Java /* * Program Demonstrate offer(E e, long timeout, TimeUnit unit) * method of ArrayBlockingQueue. */ import java.util.concurrent.ArrayBlockingQueue; import java.util.concurrent.TimeUnit; public class GFG { public static void main(String[] args) throws InterruptedException { // Define capacity of ArrayBlockingQueue int capacity = 5; // Create object of ArrayBlockingQueue ArrayBlockingQueue<Integer> queue = new ArrayBlockingQueue<Integer>(capacity); // Add elements to ArrayBlockingQueue queue.offer(423); queue.offer(233); queue.offer(356); // Print elements System.out.println("Queue Contains" + queue); // Try to poll elements System.out.println("Removing From head: " + queue.poll(10, TimeUnit.SECONDS)); System.out.println("Queue Contains" + queue); System.out.println("Removing From head: " + queue.poll(10, TimeUnit.SECONDS)); System.out.println("Queue Contains" + queue); System.out.println("Removing From head: " + queue.poll(10, TimeUnit.SECONDS)); System.out.println("Queue Contains" + queue); System.out.println("Removing From head: " + queue.poll(10, TimeUnit.SECONDS)); } }
Output:Queue Contains[423, 233, 356] Removing From head: 423 Queue Contains[233, 356] Removing From head: 233 Queue Contains[356] Removing From head: 356 Queue Contains[] Removing From head: null
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