Since Processing IS java, you can just use the method from that page as it is.

Seems to work fine...

Code Example

1. int[] someData = { 0, 28, 5, 9, 6, 19 };
2.  
3. void setup() {
4.   println("Original: ");
5.   println(someData);
6.   int[] sorted = quickSort(someData);
7.   println("\nSorted: ");
8.   println(sorted);
9.   exit();
10. }
11.  
12. int[] quickSort(int[] data) {
13.   int lenD = data.length;
14.   int pivot = 0;
15.   int ind = lenD/2;
16.   int i, j = 0, k = 0;
17.   if (lenD<2) {
18.     return data;
19.   } else {
20.     int[] L = new int[lenD];
21.     int[] R = new int[lenD];
22.     int[] sorted = new int[lenD];
23.     pivot = data[ind];
24.     for (i=0;i<lenD;i++) {
25.       if (i!=ind) {
26.         if (data[i]<pivot) {
27.           L[j] = data[i];
28.           j++;
29.         }
30.         else {
31.           R[k] = data[i];
32.           k++;
33.         }
34.       }
35.     }
36.     int[] sortedL = new int[j];
37.     int[] sortedR = new int[k];
38.     arraycopy(L, 0, sortedL, 0, j);
39.     arraycopy(R, 0, sortedR, 0, k);
40.     sortedL = quickSort(sortedL);
41.     sortedR = quickSort(sortedR);
42.     arraycopy(sortedL, 0, sorted, 0, j);
43.     sorted[j] = pivot;
44.     arraycopy(sortedR, 0, sorted, j+1, k);
45.     return sorted;
46.   }
47. }

its working now, not totally sure what was wrong. thank you

You only had a lone function, which needed to be called and fed w/ an Array parameter.
After that, ther function spits the result as Array as well! 

amnon.owed only created, within setup(), an Array to be sent to the sort function,
and then, displayed the result.

At least, that's what I believe all he's done.
Whether the function needed some extra fix I haven't paid attention!