8. OS versions

Moving targets can be challenging.

Google has minimised the disruption caused by API changes across Android releases, and documented them very well, but there are still a few things you need to be aware of. The SDK lets you test your app on multiple platforms with its AVD (Android Virtual Device) support. You can also specify the minimum version to allow in your app descriptor file, AndroidManifest.xml. This means that when a user attempts to install your app on a device with a lower version than that which it was targeted for, they will be told immediately and they won't be able to. This is preferable to running apps on unsupported platforms as it could fail in unpredictable ways.

Android releases are named after desserts, so we had Cupcake (1.5), Donut (1.6) and Eclair (2.0), the next two are rumoured to be Flan and Gateaux - in case you hadn't spotted it, there's an alphabetic progression there ;-)

The usual rules regarding writing code for undocumented features apply, and this is much easier to do when you are dealing with a full open source system as you can see exactly what those functions are and do. Basically - avoid them! Quite a few folk got their fingers burnt when apps out there in the market targeting 1.5 started failing when the 1.6 release was rolled out to end users. There are similar reports for Droid too, which runs Android 2.0. On that point developers can fairly cry foul as none had access to Android 2.0, so there is nothing for it but to rebuild and release - but pay careful attention to those deprecation warnings.