The
ConcurrentLinkedQueueis a thread-safe, unbounded queue. The elements are ordered by FIFO (First-In-First-Out). The elements are inserted at the tail (end) and retrieved from the head (start) of the queue. Null elements are not allowed in the queue. We can use theConcurrentLinkedQueuewhen multiple threads are sharing a single queue.
The element method can be used to get the head of the ConcurrentLinkedQueue object.
public E element()
This method doesn’t take in any parameters.
This method retrieves the head of the queue. If the queue is empty, then a NoSuchElementException is thrown.
This method is similar to the
peekmethod, except that theelementmethod throws theNoSuchElementExceptionif the queue is empty, whereas thepeekmethod returnsnull.
The code below demonstrates how to use the element method.
import java.util.concurrent.ConcurrentLinkedQueue;class Element {public static void main( String args[] ) {ConcurrentLinkedQueue<String> queue = new ConcurrentLinkedQueue<>();queue.add("1");queue.add("2");queue.add("3");System.out.println("The queue is " + queue);System.out.println("queue.element() returns : " + queue.element());}}
In the code above:
In line 1, we import the ConcurrentLinkedQueue class.
In line 4, we create a ConcurrentLinkedQueue object with the name queue.
In lines 5 to 7, we use the add() method of the queue object to add three elements (1, 2, 3) to queue.
In line 10, we use the element() method of the queue object to get the head. In our case, 1 will be returned.