std::make_heap equivalent in Java?

Question

STL has this really useful function. Is there any equivalent to this in Java? I could write my custom implementation but it would be useful not to reinvent the wheel.

Answer 1

std::make_heap makes a binary heap, which is used as a priority-queue and is called PriorityQueue in Java.

Correction : there isn't a standard binary-heap class in Java, but I suggested two in the comment below.

Answer 2

PriorityQueue has a special constructor that can "heapify" an exisisting ArrayList (or any Collection).

Example:

ArrayList<Integer> x = new ArrayList<>();

PriorityQueue<Integer> pq = new PriorityQueue<Integer>(x);  // O(N)

This operation copies input whereas make_heap just reorders the array in-place.