java.util · java.base · since Java 1.5

PriorityQueue

declaration

public class PriorityQueue<E> extends AbstractQueue<E>
        implements Serializable

Binary-heap queue: poll() always yields the smallest element per natural order or a Comparator. Iteration order is heap order, NOT sorted order.

Key methods

`PriorityQueue()`	Natural ordering — elements must implement Comparable.
`PriorityQueue(Comparator<? super E> cmp)`	Custom priority.
`boolean offer(E)`	Insert — O(log n); the queue is unbounded so this never returns false.
`E poll()`	Remove the minimum — O(log n), null if empty.
`E peek()`	Inspect the minimum — O(1), null if empty.