Convert a Queue to List

Question

What is the fastest way to convert a Queue into a List while keeping the Queue order?

Answer 1

The fastest is to use a LinkedList in the first place which can be used as a List or a Queue.

Queue q = new LinkedList(); List l = (List) q; 

Otherwise you need to take a copy

List l = new ArrayList(q); 

Note: When dealing with PriorityQueue, Use a loop, poll each element and add to list. PriorityQueue to List not maintaining the heap order.

Answer 2

Pass Queue To ArrayList Constructor

The easiest way to just create a ArrayList and pass your Queue as an argument in the constructor of ArrayList that takes a Collection. A Queue is a Collection, so that works.

This is the easiest way and I believe fastest way too.

List<?> list = new ArrayList<>( myQueue );