A binary heap is a heap-ordered complete binary tree which is implemented using an array. In a heap the smallest key is found at the root and since the root is always found in the first position of the array, finding the smallest key is a trivial operation in a binary heap.
In this section we describe the implementation of a priority queue as a binary heap. As shown in Figure , we define a concrete class called BinaryHeap for this purpose.
Figure: Object class hierarchy
Program introduces the BinaryHeap class. The BinaryHeap class extends the AbstractContainer class introduced in Program and it implements the PriorityQueue interface defined in Program .