Programming Android: first impressions

I suspended work on Comefrom0x10 for a little while to start my first attempt at a serious Android app. It is tentatively called “Text Collector” and essentially just makes a pdf of your text messages.

So, how is Android as a platform?

Well, first, it’s Java. This means that half my code is type declarations, the other half is keywords; we all saw that coming, move along…

The Android core api is unpleasant to use, but it could have been worse. Its main problem is severe under-documentation, apparently thanks to a bad case of “source code is the documentation” syndrome.

Though technically Java, for better or worse, it feels like an api designed by people who would rather write C. Integer constants and bitmasks are everywhere; there is even the occasional “out” parameter. On the bright side, there is a refreshing lack of abstract factory singletons. There is no xml standing in for “dependency injection” code.

There is plenty of xml for defining layouts, though. Layout xml is attribute-heavy, which means less verbose than it could have been, but also that you can’t put comments in many places where they ought to go:

<Frobnicator
  android:foo="bar" <!-- could use a comment here, but that's illegal -->
...

Thankfully, layouts and resource definitions appear to be the only places you have to use xml. In principle, you could define layouts entirely in Java, but frying pan, meet fire.

As far as I can tell, the entire Java standard library is available, but I’ve used only a few small parts of it. There are bizarro-world Android replacements of some parts. Methods that expect uris take android.net.Uri instead of java.net.URI. Bundle of Parcelable looks like it probably could just have been Map<String,Serializable>. I haven’t spent enough time with Android code to judge whether there are good reasons for this seeming duplication.

Like many apis, the core library is a mix of surprisingly easy juxtaposed with surprisingly difficult. There are some nice included layouts and widgets, like a date picker, but try hooking up a date picker to a TextView with inputType=date, and you are in for nasty surprises. Writing and displaying pdf is almost trivial, but if you want zoom and two-dimensional scrolling while you display it, expect pain.