There's a project that I would like to implement that would require me to implement a simple Ethereum wallet client for Android. I would like to know the basic building blocks for making such an application. I know about Trust Wallet and Lunary Wallet as open source examples, if you will, of an android wallet. But I was more or less looking for something more barebones..specifically, an application that can generate ethereum private keys in plain text so I can further understand the direction I want to take the project in. I would also, if possible, not like the project to be routed through a web service like myetherwallet. I want it to be fully functional as a native application. Thank you Etheropians!