title: Android: Null Pointer Exception setContentView
body: <p>What I is wrong?
  If I click on the Registrieren Button, the app will be stopped.
  Project files:
  <a href="https://github.com/JonasFranzDEV/LaMamma" rel="nofollow">https://github.com/JonasFranzDEV/LaMamma</a></p>