An unbounded priority queue based on a priority heap.
The elements of the priority queue are ordered according to their
natural ordering, or by a
provided at queue construction time, depending on which constructor is
used. A priority queue does not permit
A priority queue relying on natural ordering also does not permit
insertion of non-comparable objects (doing so may result in
The head of this queue is the least element
with respect to the specified ordering. If multiple elements are
tied for least value, the head is one of those elements -- ties are
broken arbitrarily. The queue retrieval operations
element access the
element at the head of the queue.
A priority queue is unbounded, but has an internal capacity governing the size of an array used to store the elements on the queue. It is always at least as large as the queue size. As elements are added to a priority queue, its capacity grows automatically. The details of the growth policy are not specified.
This class and its iterator implement all of the
optional methods of the
Iterator interfaces. The Iterator provided in method
iterator() is not guaranteed to traverse the elements of
the priority queue in any particular order. If you need ordered
traversal, consider using
Note that this implementation is not synchronized.
Multiple threads should not access a
instance concurrently if any of the threads modifies the queue.
Instead, use the thread-safe
Implementation note: this implementation provides
O(log(n)) time for the enqueuing and dequeuing methods
linear time for the
methods; and constant time for the retrieval methods
This class is a member of the Java Collections Framework.
|the type of elements held in this collection|