Which is the best java app builder for android?

Answer 1

I use Android Studio, you can consider using it.

Answer 2

If you wanna create apps on your android device

You can download this app, I use it alot
https://drive.google.com/file/d/1HLJxH3020d0nPrNJGy8ZzNc76a85K3Du/view?usp=drivesdk