How to iterate over a PriorityQueue?

java collections loops priority-queue
simpatico picture simpatico · Nov 14, 2011 · Viewed 59.9k times · Source 
for (Event e : pq)

doesn't iterate in the priority order.

while(!pq.isEmpty()){
  Event e = pq.poll();
}

This works but empties the queue.

Answer

Oliver Charlesworth picture Oliver Charlesworth · Nov 14, 2011

From the Javadocs

The Iterator provided in method iterator() is not guaranteed to traverse the elements of the PriorityQueue in any particular order. If you need ordered traversal, consider using Arrays.sort(pq.toArray()).

There are probably other equivalent mechanisms.

Related questions

Ways to iterate over a list in Java

Being somewhat new to the Java language I'm trying to familiarize myself with all the ways (or at least the non-pathological ones) that one might iterate through a list (or perhaps other collections) and the advantages or disadvantages of each. …

Read More
Initialization of an ArrayList in one line

I wanted to create a list of options for testing purposes. At first, I did this: ArrayList<String> places = new ArrayList<String>(); places.add("Buenos Aires"); places.add("Córdoba"); places.add("La Plata"); Then, I …

Read More
How do I efficiently iterate over each entry in a Java Map?

If I have an object implementing the Map interface in Java and I wish to iterate over every pair contained within it, what is the most efficient way of going through the map? Will the ordering of elements depend on …

Read More