Q:

Garbage Collection Impact of independent arraylist building vs Comparator logic

Question to the gurus in Java Garbage Collection. Wanted to understand if/any performance impact to the Heap Memory when we do sorting via the following techniques
Collection of objects with a unique member variable
ArrayList<Car> 

Class Car{
boolean preferredVehicle;
}

Now we need to sort and show the preferredVehicles to the top of a selection list
Method 1:

Create two Lists one regularList and one PreferredList
Iterate the CarList and then add to PreferredList if boolean is true
Add the non Preferred Car to the non PreferrdList
Add All non preferred to the complete Preferred List once Car List loop completes

Method 2 :
Collections.sort with a Comparator 
Is there a quantifiable difference in performance and which one is more friendly in future garbage collection and heap memory consumption

A:

2 lists will definitely acquire more space and imagine the list being huge.And, if you won't preallocate the desired list capacity, adding an element can result into another list object allocation of double the size and thus more work for gc. 
Apply sorting on the same list if you don't care the original order.

