//modifications given for Programming Projects 12.6 and 12.7
public class QuickSortDemo
{
	public static void sort(double[] a, int start, int stop) 
	{

		if (stop - start == 1) {
			if (a[start] > a[stop]) {

				double temp = a[start];
				a[start] = a[stop];
				a[stop] = temp;
			}
		} else if (stop - start > 1)
		{
	
			int splitPoint = split(a, start, stop);
			sort(a, start, splitPoint);
			sort(a, splitPoint + 1, stop);
		}
	}

	private static int split(double[] a, int start, int stop)
	{

		double[] temp;

		int size = (stop - start + 1);
		temp = new double[size];
		int middle = (stop + start) / 2;
		double splitValue = a[middle];
		int up = 0;
		int down = size - 1;
		for (int i = start; i < middle; i++) 
		{
			if (a[i] <= splitValue) {
				temp[up] = a[i];
				up++;
			} else {
				temp[down] = a[i];
				down--;
			}
		}
		for (int i = middle + 1; i <= stop; i++)
		{
			if (a[i] <= splitValue)
			{
				temp[up] = a[i];
				up++;
			} else
			{
				temp[down] = a[i];
				down--;
			}
		}

		System.out.println(up + " " + down);
		temp[up] = splitValue;
		for (int i = 0; i < size; i++)
			a[start + i] = temp[i];

		return middle;
	}
	public static void main(String args[]) 
	{
		double[] ele = {1, 2, 6, 4, 3, 7, 10, 24, 25, 26, 19, 17, 30};

		System.out.println("Sorting elements are:");	
		sort(ele, 0, ele.length - 1);
		for (int i = 0; i < ele.length; i++)
			System.out.println(ele[i]);
	}
}

Output of the program:

Sorting elements are:
1.0
2.0
3.0
4.0
6.0
7.0
10.0
17.0
19.0
24.0
25.0
26.0
30.0