Android developer support and Helpful Online Forums List.

android-developer-support-list
App development or Android App development is leading technology growing well because of smartphones. To clear doubts and improve the knowledge on app developments there are a lot of forums on there.
What are android development and help and supports forums?
An Online forum is associated as a notice board or discussion section. The main objective is to provide an area where visitors or members can interact with questions, answers, and discussions on their topic or doubt.

Also, read: Thunkable Vs Android studio Which one better for App building.
Note: Each forum states the topic and tries to keep the discussions on the topic. However, this can often vary from forum to forum as forums can fall under categories.

Here Are some top active Android developer forums which will gonna help you a lot:
Google Groups
Stack Overflow
XDA-Developers Android Forums
Android Forums
DreamInCode.net
Developer Forums
Mobile Applications forum
App Development | Mobile Ministry Forum
Mobile App Development
Mobile Apps Forum
android.net
droidforums.net
androidpit.com
Forums
Android Forums at AndroidCentral.com
anddev.org • Index page and finally,
Mobile App Developers Forum
Android app developers should refer above forums for their Android app development.

Also Read: Android Studio Most Important Common Questions with Answer.
There are many forums out there for Android development discussions I'm listing a few here which have most active developers and discussions.