I am upgraded to: Kotlin 1.4.30 Compose 1.0.0-alpha12 NavigationCompose 1.0.0-alpha07 I get this err...

# compose

[Daniele B]

I am upgraded to:
Kotlin 1.4.30
Compose 1.0.0-alpha12
NavigationCompose 1.0.0-alpha07
I get this error:

java.lang.NoClassDefFoundError: Failed resolution of: Landroidx/activity/compose/LocalOnBackPressedDispatcherOwner;
    at androidx.navigation.compose.NavHostKt.NavHost(NavHost.kt:83)
    at androidx.navigation.compose.NavHostKt.NavHost(NavHost.kt:59)
    at myapp.android.NavigationKt.Navigation(Navigation.kt:22)

any idea?

[Ian Lake]

Upgrade to Activity Compose alpha02: https://kotlinlang.slack.com/archives/CJLTWPH7S/p1613068198230100?thread_ts=1613067938.229500&cid=CJLTWPH7S

[Daniele B]

thanks! It fixed it
However I still have another error:

[Daniele B]

which I don’t understand, as I am actually using 1.4.30

[jim]

The problem is that your IDE is still using an old Kotlin plugin, since AndroidStudio with stable 1.4.30 hasn't yet been released, so you'll need to change your kotlin update channel. Assuming you are on a recent/latest canary, you should be able to open "Preferences" > "Languages & Frameworks" > "Kotlin", and then change the "Update Channel"

[Daniele B]

thanks @jim I was able to download the preview Kotlin 1.4.30 plugin!

[Daniele B]

@Ian Lake
I now have:

implementation("androidx.activity:activity-ktx:1.2.0")
implementation("androidx.activity:activity-compose:1.3.0-alpha02")

do I need both?

[Daniele B]

in general, do I need all first 5 dependencies for a compose-only app?

[Daniele B]

• core-ktx
• activity-ktx
• activity-compose
• material
• appcompat

[Ian Lake]

activity-compose has activity-ktx as a transitive dependency, so you definitely don't need both of those (just activity-compose is enough)

[Daniele B]

thanks, at least one goes away

[Ian Lake]

The rest of them are perhaps more of a "do you need them" question. activity-ktx will already give you core-ktx:1.1.0 (so the question is do you specifically want extensions from the newer version? Only then do you need to declare what specific version you want) and a pure compose app with no Views whatsoever doesn't need material or appcompat either (as those are primarily View focused dependencies)

[Ian Lake]

If you are using AppCompatActivity for whatever reason, then you should use appcompat:1.3.0-beta01 as it is the 1.3 releases that populate the ViewTree APIs compose depends on (if you're only using ComponentActivity, then you're fine - that potential issue only applies specifically to AppCompatActivity)

[Daniele B]

@Ian Lake
I am currently using:

class MainActivity : AppCompatActivity() {

  private val appViewModel: AppViewModel by viewModels()

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContent {
      MyAppTheme(appViewModel.KMPModel) {
        Navigation(appViewModel.KMPModel)
      }
    }
  }

}

I didn’t know about ComponentActivity, is it new?

[Ian Lake]

It has been the base class under AppCompatActivity and FragmentActivity for a year and a half or so now

[Ian Lake]

Keep in mind that Compose also has APIs for getting a ViewModel, there's no advantage of using the Activity APIs in this case: https://developer.android.com/jetpack/compose/interop#viewmodel

[Daniele B]

I didn’t know about ComponentActivity !
The code snippet on JetpackCompose tutorial page uses: AppCompatActivity
https://developer.android.com/jetpack/compose/tutorial
I have just replaced AppCompatActivity with ComponentActivity in my app and it seems to work correctly. So, can I safely use it?

[Ian Lake]

If you have no Android Views and aren't using any AppCompat APIs or any Fragment APIs, then AppCompatActivity isn't really doing anything for you and, yep, ComponentActivity should be enough

[Ian Lake]

Not every app is as lucky to be working in the pure Compose world right from the start. For those cases, AppCompatActivity makes more sense as a general recommendation that will give you a working solution in Compose without having to make changes later if you end up needing an AndroidView that assumes AppCompat, Material, etc. is available

[Daniele B]

Thanks @Ian Lake!
So, I guess if I want to use some WebViews, I would need to use AppCompatActivity, or do you expect to release WebViews for Compose?

[Ian Lake]

WebView is a weird one, since it is a black box into web content and web content doesn't rely on AppCompat hooks either.

[Daniele B]

Interesting, to know!