By following standard coding style and guidelines, we can build a better android application.
If you follow a standard coding style in android, it will be easier for you and also for others to understand your code easily.
The following are the sources from where I learned the standard coding style and guidelines :
From here you can learn the coding style that you should follow while contributing to android source code.
#2 . Project Guidelines
Here you will get to know about the file naming, parameter ordering in methods, class member ordering, etc.
Here you will get to know about the MVP pattern used in android development.
Here you will learn how to name layout, drawable files.
Here you will get to learn about java coding style.
Here is my article about Android development best practices.