linkRandom musing on Jetpack Compose

Compose is a new reactive-style ui framework for android. After poking around in the source code, there are some interesting architectural decisions I would like to highlight:

  1. It is actually quite ambitious, instead of binding to TextView etc, it is laying out and rendering the ui itself. There will be interoperability with existing views but it represents a whole to way to render ui on android.
  2. It’s completely written in kotlin using the kotlin compiler plugin api. I don’t believe there will be a way to define your ui using java with this. Yet another reason to advocate for kotlin for android apps!
  3. The android parts are completely abstracted out. This means testing ui is going to potentially be very easy. It also means that there's no reason this couldn’t be made to work on iOS with kotlin native. I doubt it’s on anyone’s roadmap but it's certainly an interesting idea.
  4. The syntax is more 'magical' than other reactive frameworks. Instead of returning your ui, you construct it by calling functions that are annotated with @Composable. State is updated by either annotating values with @Model. Or by wrapping them in a state {} function to create a delegate. Opinions may very on if they went too far, but I’m personally a fan.

2linkfun CustomRadioGroup() {

3link val radioOptions = listOf("Disagree", "Neutral", "Agree")

4link var selectedOption by +state { radioOptions[0] }

5link val textStyle = +themeTextStyle { subtitle1 }


7link RadioGroup {

8link Row(mainAxisSize = MainAxisSize.Min) {

9link radioOptions.forEach { text ->

10link val selected = text == selectedOption

11link RadioGroupItem(

12link selected = selected,

13link onSelected = { selectedOption = text }) {

14link Padding(padding = 10.dp) {

15link Column {

16link RadioButton(selected = selected)

17link Text(text = text, style = textStyle)

18link }

19link }

20link }

21link }

22link }

23link }


Random musing on Jetpack Compose

Home You Dont Need to Null Out Views Some More Biometric Messes The Mess that is Android Biometrics Random musing on Jetpack Compose