PriorityBlockingQueue add() Method in Java (original) (raw)

Last Updated : 13 May, 2022

The add(E e) method of PriorityBlockingQueue inserts the element passed as a parameter to the method at the tail of this PriorityBlockingQueue. This method returns true if the adding of the element is successful. Else it returns false.

Syntax:

public boolean add(E e)

Parameter: This method takes a mandatory parameter e which is the element to be inserted in PriorityBlockingQueue.

Returns: This method returns a boolean response. It returns true if the adding of the element is successful, else it returns false.

Exception: This method throws following exceptions:

• ClassCastException: if the element passed as parameter cannot be compared to the element contained by queue to keep priority queue’s ordering.
• NullPointerException: if the element passed as parameter is null.

Below program illustrate add() method of PriorityBlockingQueue:

Example 1:

Java

import java.util.concurrent.PriorityBlockingQueue;

public class GFG {

`` public static void main(String[] args)

`` {

`` int capacity = 15 ;

`` PriorityBlockingQueue<Integer> PrioBlockingQueue

`` = new PriorityBlockingQueue<Integer>(capacity);

`` PrioBlockingQueue.add( 526734 );

`` PrioBlockingQueue.add( 84879456 );

`` PrioBlockingQueue.add( 4586415 );

`` System.out.println("After Adding Some Numbers");

`` System.out.println("PriorityBlockingQueue:"

`` + PrioBlockingQueue);

`` PrioBlockingQueue.add( 156116 );

`` PrioBlockingQueue.add( 61651191 );

`` System.out.println("\nAfter adding Some More Numbers");

`` System.out.println("PriorityBlockingQueue:"

`` + PrioBlockingQueue);

`` }

}

Output:

After Adding Some Numbers PriorityBlockingQueue:[526734, 84879456, 4586415]

After adding Some More Numbers PriorityBlockingQueue:[156116, 526734, 4586415, 84879456, 61651191]

Example 2: To demonstrate NullPointerException thrown by add() method.

Java

import java.util.concurrent.PriorityBlockingQueue;

public class GFG {

`` public static void main(String[] args)

`` {

`` int capacity = 15 ;

`` PriorityBlockingQueue<Integer> PrioBlockingQueue

`` = new PriorityBlockingQueue<Integer>(capacity);

`` PrioBlockingQueue.add( 526734 );

`` PrioBlockingQueue.add( 84879456 );

`` PrioBlockingQueue.add( 4586415 );

`` try {

`` PrioBlockingQueue.add( null );

`` System.out.println("PriorityBlockingQueue:"

`` + PrioBlockingQueue);

`` }

`` catch (Exception e) {

`` System.out.println("Exception when adding null : "

`` + e);

`` }

`` }

}

Output:

Exception when adding null: java.lang.NullPointerException

Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/PriorityBlockingQueue.html#add-E-