What is the ConcurrentLinkedQueue.isEmpty() method in Java?

The ConcurrentLinkedQueue is 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. The null elements are not allowed as an element of the queue. We can use the ConcurrentLinkedQueue when multiple threads are sharing a single Queue.

The isEmpty method can be used to check if the ConcurrentLinkedQueue object has no elements.

Syntax

public boolean isEmpty()

Parameters

This method does not take any arguments.

Return value

This method returns true if the queue object has no elements. Otherwise, it returns false.

Code

The code below demonstrates how to use the isEmpty method.

import java.util.concurrent.ConcurrentLinkedQueue;
class IsEmpty{
    public static void main( String args[] ) { 
      ConcurrentLinkedQueue<String> queue = new ConcurrentLinkedQueue<>();
      System.out.println("The queue is : " + queue);
      System.out.println("Check if the queue is empty : " + queue.isEmpty());
      queue.add("1");
      System.out.println("\nThe queue is : " + queue);
      System.out.println("Check if the queue is empty : " + queue.isEmpty());
    }
}

Explanation

In the code above:

  • In line 1, we import the ConcurrentLinkedQueue class.

  • In line 4, we create a ConcurrentLinkedQueue object with the name queue. This object doesn’t have any elements in it.

  • In line 6, we call the isEmpty method on the queue object. This method will return true because the queue object is empty.

  • In line 8, we use the add() method of the queue object to add one element ("1") to queue.

  • In line 10, we call the isEmpty method on the queue object. This method will return false because the queue object contains one element.

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