Development notes

Coding style

  • Prefer initializing properties inline over spelling them out in a separate init { block.

  • Use annotations (@Foo) only when it makes the code easier to read.

  • Prefer references (Foo) over nullable references (Foo?).

  • Prefer variable names which are not keywords over working the problem around with backticks ('is').

  • Prefer constructs like foo?.let { over non-null assertions (!!).

Complex parts of the app

The app code is quite simple, this is just fancy stopwatch after all. But some parts are nontrivial:

  • Making sure that the timer doesn't stop, by launching a proper background service was hard to figure out.

  • The icon was surprisingly challenging to add, mostly because every SVG editor will just scale your image, but exactly scaling is ignored by Android Studio's SVG import.

  • The recycler view was tricky to set up: most examples are overcomplicated, when really what was needed here is just an adapter and a holder class.


If you are used to Java, then not spelling out type names all over the place is confusing in Kotlin. See on how to let Android Studio show these types for you without polluting the code.


You are supposed to go via the Android logging framework, one possible (temporary, local) debug printf:

Log.e(TAG, "debug, myFunc: myVar is " + myVar)

This way it stands out from the stock debug messages when you filter for package:mine in the Logcat tab in Android Studio.