Mobile and multiplatform work — Compose, Kotlin, data, and shipping.
101 posts
One hundred days working through the official Jetpack Compose documentation in order, one topic a day. It starts from what you already know, and ends with the eight ideas the whole toolkit keeps circling. Each post takes a symptom, explains the mechanism underneath it, and shows how to prove it on a real device.
A hundred days of Jetpack Compose, written by following the official documentation end to end. The APIs are many and the ideas are few; here are the eight that kept recurring, and an honest account of what the exercise missed.
Glance lets you write widgets in Compose-like Kotlin, but it emits RemoteViews rather than drawing. Knowing that explains the missing modifiers, the absent animations, and why state works the way it does.
A notification is rendered by the system UI, not your app, so Compose plays no part in its appearance. What a Compose app owns is the permission flow, the deep link, and the back stack the user lands in.
Predictive back shows a preview of the destination during the gesture. Supporting it means responding to progress rather than to a completed press, and the old BackHandler cannot express that.
Compose exposes system insets as composable values with padding, size and consume modifiers. Knowing the three safe-inset groups and how the keyboard inset animates resolves most edge-to-edge layout problems.
Targeting Android 15 makes edge-to-edge mandatory — the opt-out is gone. What that changes, what breaks, and why the fix is mostly about who consumes the insets.
Compose ships lint rules for the modifier convention, remember misuse, unstable collections and more. Adding your own is how a design-system convention becomes a build failure instead of a code-review comment.
Layout Inspector renders the composition as an inspectable tree with per-composable recomposition and skip counts. Knowing what it can and cannot tell you is the difference between a diagnosis and a guess.
@Preview renders a composable without running the app. Its real value is the pressure it applies: a component that can't be previewed is a component that can't be tested, and both point at the same design problem.
Navigation Compose and the fragment navigator can coexist in one NavHost via the fragment interop artifact. That shared back stack is what makes an incremental screen-by-screen migration possible.
A RecyclerView migration removes most of its own machinery, because Compose's composition already does recycling and diffing. What survives is stable identity — getItemId becomes key — and knowing that makes the port mechanical.
AndroidView embeds a View inside Compose. Its factory lambda constructs, its update lambda binds, and conflating them causes either a View recreated per frame or one that never reflects new state.
