ArrayBlockingQueue is a bounded queue and it is thread-safe. It uses a fixed-size array internally so that its size cannot change after declaration. The elements of this queue follow null objects are not allowed as elements in this queue.
The isEmpty method can be used to check if the ArrayBlockingQueue object is empty (contains no element).
public boolean isEmpty()
This method doesn’t take any arguments.
This method returns true if the queue contains no elements. Otherwise, false is returned.
The code below demonstrates how to use the isEmpty method.
import java.util.concurrent.ArrayBlockingQueue;class IsEmpty {public static void main( String args[] ) {// Declare a ArrayBlockingQueue with String type elemetns. The size of the queue is set to 5.ArrayBlockingQueue<String> queue = new ArrayBlockingQueue<>(5);// Print the Queue. It should be emptySystem.out.println("The queue is " + queue);// Check if the Queue is empty. It should return trueSystem.out.println("queue.isEmpty() - " + queue.isEmpty());// Add a string to the queuequeue.add("1");// Check the queue againSystem.out.println("\nAfter adding 1.The queue is " + queue);// Check if the queue is empty. It should return falseSystem.out.println("queue.isEmpty() - " + queue.isEmpty());}}
In the code above:
In line 1, we import the ArrayBlockingQueue from the java.util.concurrent package.
In line 5, we create an object for the ArrayBlockingQueue class with the name queue and size 5.
In line 9, we use the isEmpty method to check if the queue is empty. In our case, true is returned because the queue has no elements.
In line 11, we call the add method to add the element "1" to the queue object.
In line 15, the isEmpty method returns false because the queue contains 1 element.