Java 9 Programming By Example

Non-recursive sorting

To demonstrate that even non-tail recursive methods can be expressed in a non-recursive way, here is the quick sort that way:

public class NonRecursiveQuickSort<E> {     // injected final fields and constructor deleted from print      private static class Stack {         final int begin;         final int fin;         public Stack(int begin, int fin) {             this.begin = begin;             this.fin = fin;         }     }     public void qsort(SortableCollection<E> sortable, int start, int end) {         final List<Stack> stack = new LinkedList<>();         final Partitioner<E> partitioner = new Partitioner<>(comparator, swapper);         stack.add(new Stack(start, end));         int i = 1;         while (!stack.isEmpty()) {             Stack iter = stack.remove(0);             if (iter.begin < iter.fin) {  final E pivot = sortable.get(iter.begin); ...