Is it possible to set the timezone of an android device (either a physical device or and emulator) to a timezone that doesn't actually exist (for instance, GMT+00:03 or GMT-500:00)? I tried reading the docs, and it seems like the data type supports that in theory, but I have no idea how you'd actually do that in practice, or if there's some reason it's impossible that I'm missing.
Not without using/creating a Custom ROM
So the link you provided is for Android app developers who need to create custom timezone for their usage within Android Apps. Other apps wouldn't be affected by any internal time/date calculation or settings done in that manner.
You can set an emulator's timezone on startup:
Android Emulator command line options
-timezone timezone
Set the timezone for the virtual device to timezone, instead of the host timezone
By default, the emulator uses the timezone of your development computer. Use this option to specify a different timezone or if the automatic detection isn't working correctly. The timezone value must be in zoneinfo format, which is area/location or area/subarea/location. For example:
- America/Los_Angeles
- Europe/Paris
- America/Argentina/Buenos_Aires
The specified timezone must be in the zoneinfo database.
But you are limited to the existing timezone in the zoneinfo database (also known as tzdata).
Date/Time/Timezone rules are complicated so the Android Open Source Project has a section on Time Zone Updates.
What this means is that the complexity of time zone management is 'centralized' into tzdata and tzlookup.xml files. As tzdata database is used by many other systems and maintained by the Internet Assigned Numbers Authority organization, the mechanism by which you can modify the file is off-topic as it is not Android specific.
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