Queue is an Interface present in java.util.Queue. Queue supports all Collections methods and other methods like
peek() : returns the highest priority queue and do not removes from the queue.
poll() : returns the highest priority queue and removes from the queue
offer(): add elements to the Priority Queue
These 3 methods are present only in Queue Interface. LinkList class also implements Queue Interface.
PriorityQueue : Is added in Java 5, PriorityQueue (PQ) is different from normal queue (FIFO) as PQ maintains the list as Priority IN and Priority OUT, the elements are ordered either in natural ordering or using comparator.
aruna sameera wrote:no i am asking in general datas structure.
Queues typically order elements in a FIFO (First-In-First-Out) and PriorityQueue orders the element using the provided comparator or the natural ordering of the elements. Check those links I gave above.
aruna sameera wrote:how to implement a stack using two queues ?
It would have been better to start a new thread, since that is a new subject.
And we don't simply give out such answers: you would do well to search and find a tutorial about the data structures for stacks and queues. Then tell us what you have learned and concluded, and we'll see what we think of it