About Pankaj Kumar
We know that Queue follows First-In-First-Out model but sometimes we need to process the objects in the queue based on the priority. For example, let’s say we have an application that generates stocks reports for daily trading session and it processes a lot of data and takes time to process it. So customers are sending request to the application that is actually getting queued but we want to process premium customers first and standard customers after them. So in this case PriorityQueue implementation in java can be really helpful.
PriorityQueue class was introduced in Java 1.5 and part of Java Collections Framework. PriorityQueue is an unbounded queue based on a priority heap and the elements of the priority queue are ordered by default in natural order or we can provide a Comparator for ordering at the time of instantiation of queue.
PriorityQueue doesn’t allow null values and we can’t create PriorityQueue of Objects that are non-comparable, for example any custom classes we have. We use java Comparable and Comparator interfaces for sorting Objects and PriorityQueue use them for priority processing of it’s elements.
Source : http://www.javacodegeeks.com/2013/07/java-priority-queue-priorityqueue-example.html
