What is the ArrayBlockingQueue.add method in Java?
Overview
An ArrayBlockingQueue is a bounded, thread-safe queue. Internally, it uses a fixed-size array. Once the object is created, the size cannot be changed. It also uses FIFO (First-In-First-Out) ordering. Elements are inserted at the end of the queue and retrieved from the head of the queue. Also, null objects are not allowed as elements.
The add method can be used to add an element to the end of the queue. The element will be added only if the queue is not full. Otherwise, an IllegalStateException will be thrown.
Syntax
public boolean add(E e)
Parameters
This method takes the element to be added to the queue as an argument.
Return value
This method returns true if the element is added to the queue successfully.
Code
The code below demonstrates how to use the add method.
import java.util.concurrent.ArrayBlockingQueue;class Add {public static void main( String args[] ) {ArrayBlockingQueue<String> queue = new ArrayBlockingQueue<>(5);queue.add("1");queue.add("2");queue.add("3");queue.add("4");queue.add("5");System.out.println("The queue is " + queue);try{queue.add("6");}catch(Exception e) {System.out.println("Exception on adding 6th element" + e);}}}
Explanation
In the above code,
-
We imported the
ArrayBlockingQueuefrom thejava.util.concurrentpackage. -
We created an object for the
ArrayBlockingQueueclass with the namequeueand size 5. -
We added five elements to the
queueobject, and now the queue is full. -
We tried adding 6th element to the queue. The queue is already full, so an
IllegalStateExceptionis thrown.
