quicksort for arraylist
public static ArrayList<Vehicle> quickSort(ArrayList<Vehicle> list)
{
if (list.isEmpty())
return list; // start with recursion base case
ArrayList<Vehicle> sorted; // this shall be the sorted list to return, no needd to initialise
ArrayList<Vehicle> smaller = new ArrayList<Vehicle>(); // Vehicles smaller than pivot
ArrayList<Vehicle> greater = new ArrayList<Vehicle>(); // Vehicles greater than pivot
Vehicle pivot = list.get(0); // first Vehicle in list, used as pivot
int i;
Vehicle j; // Variable used for Vehicles in the loop
for (i=1;i<list.size();i++)
{
j=list.get(i);
if (j.compareTo(pivot)<0) // make sure Vehicle has proper compareTo method
smaller.add(j);
else
greater.add(j);
}
smaller=quickSort(smaller); // capitalise 's'
greater=quickSort(greater); // sort both halfs recursively
smaller.add(pivot); // add initial pivot to the end of the (now sorted) smaller Vehicles
smaller.addAll(greater); // add the (now sorted) greater Vehicles to the smaller ones (now smaller is essentially your sorted list)
sorted = smaller; // assign it to sorted; one could just as well do: return smaller
return sorted;
}