Android Studio Compose Material3 template theme

Question

When you create a new project in Android Studio selecting the template Jetpack Compose Material3 you get a project which defines following in themes.xml:

<style name="Theme.ComposeMaterial3" parent="android:Theme.Material.Light.NoActionBar" />

Is this being used by the project at all since the Composables
reference Material3 styles? (ComposeMaterial3Theme)
Why does this not set as parent "Theme.Material3..."?

Gabriele Mariotti · Accepted Answer · 2022-11-04T10:24:50.493

In your app you can define more compose themes (for example in the Theme.kt file).
To apply one of them you have to wrap your composables with the favorite theme.

For example:

setContent {
    MyCustomM3Theme {
      //...your composables
    }
}

About the theme defined in the xml, you can extend a M3 theme for example: Theme.Material3.Light.NoActionBar

<style name="Theme.ComposeMaterial3" parent="Theme.Material3.Light.NoActionBar" />

but the composables don't use it. They use the compose theme.
The theme defined in the themes.xml is used in the material components library (and other small parts as status bars).

Why does this not set as parent "Theme.Material3..."?

Your theme is defined as:

@Composable
fun MyCustomM3Theme(
    darkTheme: Boolean = isSystemInDarkTheme(),
    // Dynamic color is available on Android 12+
    dynamicColor: Boolean = true,
    content: @Composable () -> Unit
) {
    //...

    MaterialTheme(  //<---
        colorScheme = colorScheme,
        typography = Typography,
        content = content
    )
}

The MaterialTheme is defined in the package androidx.compose.material3

@David Sorry my bad, I didn't understand that you was referring to the xml theme. I've updated the answer. May be there is an error in the template file, of course you can use a M3 theme, but please note that composables don't use it. — Gabriele Mariotti, Nov 04 '22 at 07:51

score 0 · Answer 2 · answered Nov 04 '22 at 08:11

Yes, it's being used. The app itself can still use xml themes for things like the status bar colour, and the app icon. A good example project is https://github.com/android/compose-samples/tree/main/Jetchat. You can see how they achieve the "material you" styling for multiple android versions using the Material3 theme in that project.
That would be a question for the template designer. In my opinion, if you look at the volume of theme based configuration required in JetChat to achieve consistent theming across multiple Android versions, I can believe that the Compose Material3 template is trying to keep things a bit more simple to highlight the concepts of material 3 in Compose. (Absolutely no evidence to back that up though).

Android Studio Compose Material3 template theme

2 Answers2