TStringList vs. TList

Question

what is the difference in using a standard

type 
  sl: TStringList 

compared to using a generic TList

type 
  sl: TList

        

Answer 1

For most purposes that TStringList has been abused in the past, TObjectDictionary is better - it's faster and doesn't need sorting.

If you need a TStrings object (generally for UI stuff, since the VCL doesn't use generics much even for XE5) use TStringList - the required casting from TObject is annoying but not a showstopper.

Answer 2

I'd probably say if you want backwards compatibility use TStringList, and if you want forward compatibility (perhaps the option to change that list of strings to say list of Int64s in the future) then go for TList.

Answer 3

From memory point of view TStringList memory usage is increased with the size of TObject pointer added to each item. TList memory usage is increased with the size of pointer added to each item. If is needed just an array of strings without searching, replacing, sorting or associative operations, a dynamic array (array of string) should be just enough. This lacks of a good memory management of TStringList or TList, but in theory should use less memory.

Answer 4

TStringList has been around a long time in Delphi before generics were around. Therefore, it has built up a handful of useful features that a generic list of strings would not have.

The generics version is just creating a new type that is identical to TList that works on the type of String. (.Add(), .Insert(), .Remove(), .Clear(), etc.)

TStringList has the basic TList type methods and other methods custom to working with strings, such as .SaveToFile() and .LoadFromFile()

If you want backwards compatibility, then TStringList is definitely the way to go.
If you want enhanced functionality for working with a list of Strings, then TStringList is the way to go. If you have some basic coding fundamentals that you want to work with a list of any type, then perhaps you need to look away from TStringList.

Answer 5

The TStringlist is one very versatile class of Delphi. I used (and abused ;-) ) its Objects property many times. It's very interesting to quickly translate a delimited string to a control like a TMemo and similar ones (TListBox, TComboBox, just to list a few).

I just don't like much TList, as TStringList satisfied my needs without needing of treating pointers (as Tlist is a list of Pointer values).

EDIT: I confused the TList(list of pointers) with TList (generic list of strings). Sorry for that. My point stands: TStringList is just a lot more than a simple list of strings.

Answer 6

• As TStringList is a descendant of TStrings it is compatible with the Lines property of TMemo, Items of TListbox and TComboBox and other VCL components. So can use cbList.Items := StringList; // internally calls TStrings.Assign