Unlike choice sort, heapsort makes not waste time with a linear-time scan of the unsorted region; rather, heap sort keeps the unsorted region in a heap data structure to more quickly find the largest component in each step. Heapsort can be thought of as an better choice sort: like choice sort, heapsort divides its input into a sorted and an unsorted region, and it iteratively shrinks the unsorted region by extracting the largest component from it and inserting it into the sorted region.

The algorithm then repeatedly swaps the first value of the list with the last value, decrease the range of values considered in the heap operation by one, and sifting the new first value into its position in the heap. This repeats until the range of considered values is one value in length.

```
package DataStructures.Heaps;
/**
* Interface common to heap data structures.<br>
* <p>Heaps are tree-like data structures that allow storing elements in a specific
* way. Each node corresponds to an element and has one parent node (except for the root) and
* at most two children nodes. Every element contains a key, and those keys
* indicate how the tree shall be built. For instance, for a min-heap, the key of a node shall
* be greater than or equal to its parent's and lower than or equal to its children's (the opposite rule applies to a
* max-heap).</p>
* <p>All heap-related operations (inserting or deleting an element, extracting the min or max) are performed in
* O(log n) time.</p>
*
* @author Nicolas Renard
*/
public interface Heap {
/**
* @return the top element in the heap, the one with lowest key for min-heap or with
* the highest key for max-heap
* @throws EmptyHeapException if heap is empty
*/
HeapElement getElement() throws EmptyHeapException;
/**
* Inserts an element in the heap. Adds it to then end and toggle it until it finds its
* right position.
*
* @param element an instance of the HeapElement class.
*/
void insertElement(HeapElement element);
/**
* Delete an element in the heap.
*
* @param elementIndex int containing the position in the heap of the element to be deleted.
*/
void deleteElement(int elementIndex);
}
```