Mark Murphy, founder of CommonsWare, is the author of The Busy Coder's Guide to Android Development, the first, largest, and most up-to-date book on Android app programming, covering Android Studio and the latest Android SDKs. This book gets updated every 2-3 months, with subscribers getting access to those updates. The latest update, Version 6.9, added coverage of Android 6.0 and Android Studio 1.4, as part of its 3,466 pages.
Heck, he even has a blog.
All code in Stack Overflow questions, answers, or comments written by Mark Murphy are hereby licensed under the Apache Software License 2.0, unless otherwise noted where that code appears on Stack Overflow. Some of that code comes from his book's GitHub repo or various other CommonsWare open source projects.