PriorityQueue add(K) in Java

add(K): This method is available in java.util.PriorityQueue class of Java.

Syntax:

boolean java.util.PriorityQueue.add(K e)

This method takes one argument. This method inserts the specified element into this priority queue.

Parameters: One parameter is required for this method.

e: the element to add.

Returns: true.

Throws:

1. ClassCastException - if the specified element cannot be compared with elements currently in this priority queue according to the priority queue's ordering.

2. NullPointerException - if the specified element is null

Approach 1: When no exception

Java

import java.util.PriorityQueue;

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

        PriorityQueue<Integer> priorityQueue = 
                             new PriorityQueue<Integer>();

        priorityQueue.add(12);
        priorityQueue.add(5);
        priorityQueue.add(10);
        priorityQueue.add(2);

        System.out.println(priorityQueue);

    }
}

Output:

[2, 5, 10, 12]

Approach 2: NullPointerException 

Java

import java.util.PriorityQueue;

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

        PriorityQueue<Integer> priorityQueue = 
                     new PriorityQueue<Integer>();

        priorityQueue.add(null);

        System.out.println(priorityQueue);

    }
}

Output:

Exception in thread "main" java.lang.NullPointerException
	at java.base/java.util.PriorityQueue.offer(PriorityQueue.java:325)
	at java.base/java.util.PriorityQueue.add(PriorityQueue.java:311)