You're using boolean in a place where what you want/meant is actually a Predicate<Blatz> (in c# this would be a Func<Blatz,bool>. I may be wrong on the specific validation type needed for swing 1.

i'm writing an applet that needs to periodically request input from the user. the input is in integer form. my first thought was to create some sort of modal dialog, but the online java tutorial ...