Quicksort in Java

public class QuickSort {
    public static void main(String[] args)
    {
        int[]     array  = {12, 11, 15, 10, 9, 1, 2, 3, 13, 14, 4, 5, 6, 7, 8};
        QuickSort sorter = new QuickSort();
        sorter.quickSort(array, 0, array.length - 1);
        System.out.println(java.util.Arrays.toString(array));
    }

    private void quickSort(int[] array, int startIndex, int endIndex)
    {
        // verify that the start and end index have not overlapped
        if (startIndex < endIndex)
        {
            // calculate the pivotIndex
            int pivotIndex = partition(array, startIndex, endIndex);
            // sort the left sub-array
            quickSort(array, startIndex, pivotIndex);
            // sort the right sub-array
            quickSort(array, pivotIndex + 1, endIndex);
        }
    }

    private int partition(int[] array, int startIndex, int endIndex)
    {
        int pivotIndex = (startIndex + endIndex) / 2;
        int pivotValue = array[pivotIndex];
        startIndex--;
        endIndex++;

        while (true)
        {
            // start at the FIRST index of the sub-array and increment
            // FORWARD until we find a value that is > pivotValue
            do startIndex++; while (array[startIndex] < pivotValue);

            // start at the LAST index of the sub-array and increment
            // BACKWARD until we find a value that is < pivotValue
            do endIndex--; while (array[endIndex] > pivotValue);

            if (startIndex >= endIndex) return endIndex;

            // swap values at the startIndex and endIndex
            int temp = array[startIndex];
            array[startIndex] = array[endIndex];
            array[endIndex] = temp;
        }
    }
}