I read sort algorithms that Java used in Arrays, so I opened jar files and read what java used when we call Array.sort();, so I found Java to check if the array's length is less then 286 and use quick sort otherwise use merge sort?
static void sort(int[] a, int left, int right,
int[] work, int workBase, int workLen) {
// Use Quicksort on small arrays
if (right - left < QUICKSORT_THRESHOLD) {
sort(a, left, right, true);
return;
}
.....