Do you mean an API entirely internal to your application? In that case, yes, you probably want to use integers (enums), not Strings, to choose what to display.

Do you mean an API entirely internal to your application? In that case, yes, you probably want to use integers (enums), not Strings, to choose what to display. If you are interfacing with other APIs that use Strings, it may make sense to just pass those through. For example loading files from disk or pulling up UI classes from the OS library using some String identifier or something. It's hard to say without more context.