Like process one loan then one returned then one loan etc?

yes

https://stackoverflow.com/questions/20141241/selecting-alternate-items-of-an-array-c-sharp Similar to this, but you would need to combine both collections first with Concat

For better performance, you can also do low level enumeration by getting the enumerator from each collection. The enumerator has a MoveNext method to move to the next item and a Current property to get the item it's currently pointing at

how do i implement this

And do the same for returns

okay thank you

You just have to check the return value of MoveNext every time

When it returns false, that means it was already pointing at the last item before the call

yesss

Or there are no items. The enumerator starts before the first item so you have to start with MoveNext

okay

And don't forget the using 🙂 no brackets needed in modern c#

Like with the StreamWriter

I had this problem once and made a custom collection class that takes multiple enumerables and uses a custom enumerator that handles all the alternating logic when MoveNext is called

Then it's as simple as foreach (var item in listA.Alternate(listB))

Btw you probably want to use properties instead of all those GetX methods.

^ this. properties are the elegant solution to getters and setters in languages like java