Example of implementing quick sort.

Quicksort.java

import java.util.Arrays;

public class QuickSort
{
	public int[] a;

	public QuickSort()
	{
		a = new int[] { 0, 6, 41, 54, 57, 874, 243, 324, 1, 23, 4, 69, 7, 104 };
	}

	public void quicksort(int lo, int hi)
	{
		int m = (lo+hi)/2;
		int pivot = a[m];
		int i = lo;
		int j = hi;
		int temp;

		System.out.println( "\nPivot: " + pivot );
		System.out.println( Arrays.toString( a ));

		if( hi - lo < 1 )
		return;

		while( j > i )
		{
			while( a[i] < pivot && i < j )
			i++;

			while( a[j] > pivot && i < j )
			j--;

			if( i < j ) {
				temp = a[i];
				a[i] = a[j];
				a[j] = temp;
			}
		}

					if( j < i ) {
				temp = a[i];
				a[i] = a[j];
				a[j] = temp;
			}

		quicksort( lo, i );
		quicksort( i == lo ? i + 1 : i, hi );
	}

	public static void main( String[] args )
	{
		QuickSort qs = new QuickSort();
		qs.quicksort( 0, qs.a.length - 1 );
	}
}