I just want to know if Java's PriorityQueue 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 binary tree ?
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.
The queue automatically heapifies on operations that mutates the queue itself, namely offer, poll, remove and add.
If you mutate an element you have to remove and re-insert it. The priority queue has no way of knowing that an element has been updated.
来源：https://stackoverflow.com/questions/44762616/does-priorityqueue-heapify-itself-if-any-object-in-the-collection-is-mutated-so