PriorityBlockingQueue add() Method in Java

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 illustrate add() method of PriorityBlockingQueue:

Example 1:

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// Java Program to Demonstrate add(E e) method
// of PriorityBlockingQueue.
  
import java.util.concurrent.PriorityBlockingQueue;
  
public class GFG {
  
    public static void main(String[] args)
    {
        // define capacity of PriorityBlockingQueue
        int capacity = 15;
  
        // create object of PriorityBlockingQueue
        PriorityBlockingQueue<Integer> PrioBlockingQueue
            = new PriorityBlockingQueue<Integer>(capacity);
  
        // add  numbers
        PrioBlockingQueue.add(526734);
        PrioBlockingQueue.add(84879456);
        PrioBlockingQueue.add(4586415);
  
        // print queue after add operation
        System.out.println("After Adding Some Numbers");
        System.out.println("PriorityBlockingQueue:"
                           + PrioBlockingQueue);
  
        // add more numbers
        PrioBlockingQueue.add(156116);
        PrioBlockingQueue.add(61651191);
  
        // print queue after add operation
        System.out.println("\nAfter adding Some More Numbers");
        System.out.println("PriorityBlockingQueue:"
                           + PrioBlockingQueue);
    }
}

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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.











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// Java Program to Demonstrate Exception 


// thrown by add(E e) method 


// of PriorityBlockingQueue. 


  


import java.util.concurrent.PriorityBlockingQueue; 


  


public class GFG { 


  


    public static void main(String[] args) 


    { 


        // define capacity of PriorityBlockingQueue 


        int capacity = 15; 


  


        // create object of PriorityBlockingQueue 


        PriorityBlockingQueue<Integer> PrioBlockingQueue 


            = new PriorityBlockingQueue<Integer>(capacity); 


  


        // add numbers 


        PrioBlockingQueue.add(526734); 


        PrioBlockingQueue.add(84879456); 


        PrioBlockingQueue.add(4586415); 


        try { 


            // try to add null to PrioBlockingQueue 


            PrioBlockingQueue.add(null); 


  


            // print PrioBlockingQueue after add operation 


            System.out.println("PriorityBlockingQueue:"


                               + PrioBlockingQueue); 


        } 


        catch (Exception e) { 


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


                               + e); 


        } 


    } 


} 



















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Output:


Exception when adding null: java.lang.NullPointerException





Reference:

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



          
          
          
          

            

    

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