I think this is a good Android roadmap https://www.instagram.com/p/CEUDewtCSWI/?igshid=1su8pxpld9khs
Course about what? Kotlin? MVVM architecture? Dependency injection?
Do you have a android:popupBackground property? Try to remove it.
are you trying with a Integer or a Double/Float?
could you set the method in the "onResume" instead of "onCreate"? Try it
Are you sure that you don't prefer Realm instead of Sqlite?
How can you write with "courier new" font type?