Hi! I'm a beginner at Android but have coded a bit of Java before.
I'm trying to figure out how I'm supposed to instantiate and use a class that does not contain any visual elements, but holds a lot of functions for processing data. My main activity, on either a button click or by pressing the back- button, shall call functions in another class, which is void of visual elements, that takes care of data processing. I like to keep my classes logically separated and this non-visual class can and will be used by other classes later throughout the application. I have hit a few speed bumps on the road and I now need some help. I have two issues; Preface: I have two classes. One called "textfields" that contains a view of a bunch of textfields and a button. This is an Activity-class. I also have a non-visual class "logic" that contains all the functions I need for logic handling of data and values. This is, in my mind, a non-Activity based class (though I might be wrong). These classes use getSharedPreferences to store and fetch values from time to time. I am also going to extend my application to make real good use of the stored values, but I need to start somewhere. :) 1: Now, for instance, in my Activity "textfields" I instantiate my visual- less class called "logic" at the onCreate() event. When the onPause() event fires in "textfields", I call a function in the "logic"-class. The "logic" class reads values stored in getSharedPreferences. Here, I get a NullPointerException when executing getSharedPreferences within the "logic"-class. I'm extending the "logic"-class with Activity, in order to be able to use the getSharedPreferences-function at all. Why am I getting a NullPointerException and how should I solve the problem? 2: I have no constructor in the "logic"-class as it has been stated on a few occasions that we instead should use onCreate(), onResume(), etc. I can't figure out when any of these events fire when I'm not using a class containing an Activity. I have tried to override and use super to chain the events, but nothing I do calls either onCreate, onResume or whichever event when I from "textfields" instantiate "logic". "Logic" doesn't seem to be running onCreate() or onResume() as a class 'usually' does. When I want to use a non-visual class, what is the better way of doing this? I also need access to getSharedPreferences. Thank you for your time, I'm appreciating any help I can get. -- You received this message because you are subscribed to the Google Groups "Android Beginners" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-beginners?hl=en
