When do I need to create a new activity and when do I need to change the view?
My app needs to do:
two big buttons(sort of menu)
A View in Android is a widget that displays something. Buttons, listviews, imageviews, etc. are all subclasses of View. When you say "change view" I assume you mean change the layout by using setContentView(). This usually only needs to be done once per activity. An Activity is basically what you are referring to as a screen. To answer your question, it sounds like you need four separate activities (one for each screen).