Priority queue

[amarkirt saroay]

HOw is the Priority queue calling the comparator in this case?
I am not able to get at what time does the comparator sort the data inside the priority queue? Does it do at Queue creation? or on calling Poll()?

Please explain...I could not find the way even after debugging...!

 import java.util.*;
class PQ {
static class PQsort
implements Comparator<Integer> { // inverse sort
public int compare(Integer one, Integer two) {
return two - one; // unboxing
}
}
public static void main(String[] args) {
int[] ia = {1,5,3,7,6,9,8 }; // unordered data
PriorityQueue<Integer> pq1 =
new PriorityQueue<Integer>(); // use natural order
for(int x : ia) // load queue
pq1.offer(x);
for(int x : ia) // review queue
System.out.print(pq1.poll() + " ");
System.out.println("");
PQsort pqs = new PQsort(); // get a Comparator
PriorityQueue<Integer> pq2 =
new PriorityQueue<Integer>(10,pqs); // use Comparator
for(int x : ia) // load queue
pq2.offer(x);
System.out.println("size " + pq2.size());
System.out.println("peek " + pq2.peek());
System.out.println("size " + pq2.size());
System.out.println("poll " + pq2.poll());
System.out.println("size " + pq2.size());
for(int x : ia) // review queue
System.out.print(pq2.poll() + " ");
}
} 

[Taariq San]

If you debug again put a breakpoint in your compare method, you'll see that it's called for both the offer() and poll() methods.
They call fixup and fixDown respectively, those 2 do the comparing.