Worked my way through the WSearch Tutorial and am attempting the 'homework'.  

Maybe you can push me in the right direction here.

I started out by making another String variable "extFilter" and started it as a null.  getting the extension was easy but how do I handle a null?

I would like to say that if extFilter was null, use the constructor with 3 params and if it's not null than use a constructer for search that has 4 params.  It seems that this would involve a lot of duplication of code - any hints as to which way I should go?