dynamically react on any user input

[GoogleCodeExporter]

I am sorry, this is not a bug, more a question or a feature request. May be its 
already explained somewhere, but I didn't found.

I wonder if there is a possible, to react dynamically on any user input?
In my concrete case, I want to offer a menue to the user, where he could choose 
an item of a dynamically created list e.g.

1: Item A
2: Item B
3: Item C
4: Item D  

I want the user to input just '1', '2' etc.. I know I can create a method and 
pass the number as parameter, but this is a bit clumsy in my case. 
Another but related question is, is it possible to react on empty lines, so if 
the user just presses enter without any command?

Original issue reported on code.google.com by f.zip...@googlemail.com on 2 Apr 2014 at 3:27