PriorityBlockingQueue add() Method in Java
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
// 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);
}
}
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
// 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);
}
}
}
Output:Exception when adding null: java.lang.NullPointerException
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/PriorityBlockingQueue.html#add-E-