PriorityBlockingQueue put() method in Java

The put(E e) method of PriorityBlockingQueue is used to add an element into this queue. This method inserts the specified element into this priority queue. Since the queue is unbounded, this method will be never be blocked.
Syntax:

public void put(E e)

Parameter: This method accepts a mandatory parameter e which is the element to be inserted in PriorityBlockingQueue.
Return Value: The method does not return anything.
Exception: This method throws following exceptions: 

• ClassCastException – if the specified element cannot be compared with elements currently in the priority queue according to the priority queue’s ordering.
• NullPointerException – if the specified element is null.

Below programs illustrate put() method in PriorityBlockingQueue:
Program 1:

Java

// Java Program Demonstrate put(E e)
// method of PriorityBlockingQueue

import java.util.concurrent.PriorityBlockingQueue;

public class GFG {
    public static void main(String[] args)
    {

        // create object of PriorityBlockingQueue
        PriorityBlockingQueue<Integer> pbq
            = new PriorityBlockingQueue<Integer>();

        // Add element using put() method
        pbq.put(1);
        pbq.put(2);
        pbq.put(3);
        pbq.put(4);

        // print elements of queue
        System.out.println("Queue: " + pbq);
    }
}

Output:

Queue: [1, 2, 3, 4]

Program 2: To demonstrate NullPointerException

Java

// Java Program Demonstrate put(E e)
// method of PriorityBlockingQueue

import java.util.concurrent.PriorityBlockingQueue;

public class GFG {
    public static void main(String[] args)
    {

        // create object of PriorityBlockingQueue
        PriorityBlockingQueue<String> pbq
            = new PriorityBlockingQueue<String>();

        // try to put null value in put method
        try {
            pbq.put(null);
        }
        catch (Exception e) {
            // print error details
            System.out.println("Exception: " + e);
        }
    }
}

Output:

Exception: java.lang.NullPointerException