title: Does PriorityQueue heapify itself if any object in the collection is mutated so that it's key(used in comparator) changes?
body: <p>I just want to know if Java's <code>PriorityQueue</code> collection automatically heapifies, if any of the keys used in the comparator is mutated, or do i need to explicitly call heapify, to order the <code>binary tree</code> ?
  I am experimenting with the data structure to use it in a cache like setting, where an object in the collection should be immediately moved to the head, as soon as it is referenced.</p>