Android developers usually follow 8-hour-per-day timing. Some companies allow developers to log in at any time and log out at any time, while others maintain a time schedule due to meetings, etc. The working hours per day might increase during release or when the project completion is lagging behind.
If you are really good at what you do and pretty experienced, the company won't bother how many hours you work per day until and unless you finish the work in time.