Got some sorting problems.

[Reality Check]

I have an array list of friends (from my friend class) and I want to sort them by first name. This is my method for sorting:

code:

public static void quickSort (ArrayList f1, int start, int end)     {         int i = start;         int k = end;         Friend f = (Friend) f1.get (i);         Friend f2 = (Friend) f1.get (k);         if (end - start >= 1)         {             Friend f3 = (Friend) f1.get (start);             String pivot = f3.getFirstName ();             while (k > i)             {                 while (f.getFirstName ().compareToIgnoreCase (pivot) >= 0 && i <= end && k > i)                 {                     i++;                     f = (Friend) f1.get (i);                 }                 while (f2.getFirstName ().compareToIgnoreCase (pivot) < 0 && k >= start && k >= i)                 {                     k--;                     f2 = (Friend) f1.get (k);                 }                 if (k > i)                     swap (f1, i, k);             }             switcher (f1, start, k);             quickSort (f1, start, k - 1);             quickSort (f1, k + 1, end);         }         else         {             return;         }     }     public static void switcher (ArrayList f1, int index1, int index2)     {         Friend temp = (Friend) f1.get (index1);         f1.set (index1, f1.get (index2));         f1.set (index2, temp);     }

I'm calling it like this (f1 is my arraylist):

code:

quickSort (f1, 0, f1.size() - 1);

When I run it, it runs fine and gets past quick sort but it is not sorted for some reason. It comes out the way it went in and I can't figure out where my logic falters.

Here is the code in context if you need it.

[Reality Check]

Hmm so I just added more friends and I get an Index out of bounds error when it's more than 1 friend and it runs if its one friend. My method works in a more constrained environment as so:

code:

// The "Qick" class. public class Qick {     static int[] array = {1, 3, 2, 12, 13, 11, 9, 8, 2, 10, 5, 3};     public static void main (String[] args)     {         quickSort (array, 0, array.length - 1);         for (int i = 0; i < array.length ; i ++)         System.out.println (array [i]);     } // main method     public static void quickSort (int array[], int start, int end)     {         int i = start;         int k = end;         if (end - start >= 1)         {             int pivot = array [start];             while (k > i)             {                 while (array [i] <= pivot && i <= end && k > i)                     i++;                 while (array [k] > pivot && k >= start && k >= i)                     k--;                 if (k > i)                     swap (array, i, k);             }             swap (array, start, k);             quickSort (array, start, k - 1);             quickSort (array, k + 1, end);         }         else         {             return;         }     }     public static void swap (int array[], int index1, int index2)     {         int temp = array [index1];         array [index1] = array [index2];         array [index2] = temp;     } } // Qick class

This works perfectly so I'm not sure why my ArrayList version in my code is giving me problems.

[Reality Check]

Ok I fixed it. It was, as expected, a stupid error that I overlooked. My first while loop should've had "<= 0" and not ">=0" and the second while loop was also the wrong way.

Also, my Friend Object declarations should have been under the parent while loop where I wrote "while (k > i)". Because I was making a friend object based on the index k ABOVE this statement, there was the possibility of a negative k and therefore an index out of bounds. I hate these stupid careless errors.

But yea, thanks to anyone that was going to answer