de.weaut.sortDemo

Class QuickSort

java.lang.Object

de.weaut.sortDemo.SortApp.SortAlgorithm

de.weaut.sortDemo.QuickSort

public final class QuickSort
extends SortApp.SortAlgorithm

Quicksort algorithm demonstration.

Author: James Gosling, his version 1.6f, 31 Jan 1995
19 Feb 1996: Fixed to avoid infinite loop discovered by Paul Haeberli. Misbehaviour expressed when the pivot element was not unique.
Modif. 15.11.2005: Albrecht Weinert (a-weinert.de)
SortApp.SortAlgorithm + minor improvements.

Version:

V.16, 16.03.2019

Author:

Albrecht Weinert

Field Summary

Fields inherited from class de.weaut.sortDemo.SortApp.SortAlgorithm

stopRequested

Constructor Summary

Constructors

Constructor and Description
QuickSort()

Method Summary

Modifier and Type	Method and Description
static void	main(java.lang.String[] args) Start as application.
void	sort(int[] a) The real sorting method.
(package private) void	sort(int[] a, int lo, int hi) The quick sort algorithm.

Methods inherited from class de.weaut.sortDemo.SortApp.SortAlgorithm

getMaxPossiVal, pause, pause, pause, startMe, stop, swap

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

QuickSort

public QuickSort()

Method Detail

sort

void sort(int[] a,
          int lo,
          int hi)

The quick sort algorithm.

This methods sorts the array a's part from index lo to index hi.
It must hold: 0 <= lo <= hi < a.length.

Parameters:

a - the array to be sorted

lo - the lower index

hi - the upper index

sort

public void sort(int[] a)

Description copied from class: SortApp.SortAlgorithm

The real sorting method.

This method has to sort the array provided as parameter. Every substantial algorithmic step has to be marked by calling one of the callback methods SortApp.SortAlgorithm.pause(int, int), SortApp.SortAlgorithm.pause(int), SortApp.SortAlgorithm.pause() directly or indirectly by utilising SortApp.SortAlgorithm.swap(int, int) for element exchanges within the array having been provided to this sort implementation.
This pausing does all else like counting steps, displaying the sorting state and else.

As substantial step to be treated this way we see

• Assignments respectively swaps within the array to be sorted
  and (only in a first loop through the array) also
• a reading / comparing access to to one or two elements.

Specified by:

sort in class SortApp.SortAlgorithm

main

public static void main(java.lang.String[] args)

Start as application.

See Also:

SortApp.SortAlgorithm.startMe()