Java - Collections.binarySearch with PriorityQueue?

Question

Hello,

Can I use Collections.binarySearch() method to search elements in a PriorityQueue? Otherwise, how can I apply search algorithms to a PriorityQueue?

I have this (class Evento implements Comparable):

    public class PriorityQueueCAP extends PriorityQueue<Evento>{

       // (...)

       public void removeEventos(Evento evento){

           Collections.binarySearch(this, evento); // ERROR!

       }
    }

And I got this error: "The method binarySearch(List>, T) in the type Collections is not applicable for the arguments (PriorityQueueCAP, Evento)"

Why?

Thanks in advance!

Answer 1

You should not apply a search algorithm to a priority queue. A priority queue is designed to provide efficient access to the highest priority element in the collection, and that is all.

I know that this is probably not the answer for which you were hoping; I've seen too many problems arise from using tools for unintended purposes, and felt I should offer a word of warning.

Answer 2

This tutorial shows you how to initiate a collection and the possible operations you can perform on it. You should keep in mind what erickson said.

Answer 3

What exactly do you need the binary search for? Your code implies that you want to use it for removing items from the priority queue. The priority queue already has the remove(item) method, and it works in O(log n) time.

If on the other hand you need a binary search just to check for existence of some item, then the PriorityQueue.contains() method can help, though it is not very efficient (it takes linear time). You should consider a TreeSet instead.