I mean that's the single responsibility principle right? Classes should do one thing and one thing only and then your methods within the class should do one thi

I mean that's the single responsibility principle right? Classes should do one thing and one thing only and then your methods within the class should do one thing and one thing only. If I'm writing a list adapter for android it should only be a list adapter. It takes its data, interprets it and converts it to present. It doesn't also do data manipulation, that's handed off to another layer. It means increased modularity.