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-