What is a priority queue?

Answer

A priority queue removes the element with the highest (or lowest) priority first, not the oldest. It’s commonly implemented with a heap, so insert/remove is O(log n).

import java.util.PriorityQueue;

PriorityQueue<Integer> pq = new PriorityQueue<>();
pq.add(5);
pq.add(1);
System.out.println(pq.poll()); // 1