[Question]: Why is `enableEdgeToEdge` called before `super.onCreate`?

[YuukiToriyama]

Which should be called first, enableEdgeToEdge or super.onCreate?
In android/compose-samples, it looks like enableEdgeToEdge is called first, is there a reason for this?

compose-samples/JetNews/app/src/main/java/com/example/jetnews/ui/MainActivity.kt

Lines 30 to 39 in e472f98

	override fun onCreate(savedInstanceState: Bundle?) {
	enableEdgeToEdge()
	super.onCreate(savedInstanceState)
	val appContainer = (application as JetnewsApplication).container
	setContent {
	val widthSizeClass = calculateWindowSizeClass(this).widthSizeClass
	JetnewsApp(appContainer, widthSizeClass)
	}
	}

[prashantshukla01]

Consider thinking about preparing a room for an event:

1. First, you would first rearrange the furniture so the guests have more room to stand and chat (enableEdgeToEdge()).
2. Then, you increase the lighting level and prepare the venue doors so everything is ready to go (super.onCreate()).
3. Finally, clean the area and prepare the ornamental pieces as well as dishes and fill them on the table (setContent()).

Now, if we assume that the light were to be turned on ahead of rearranging the furniture (step 1 and step 2 reverse order), you would notice that the aesthetics with the lights on is not appealing at all. Calling enableEdgeToEdge() first tells Android, "Hey, use the entire screen before you start building the UI ”

The order of steps having execution sequence:

enableEdgeToEdge() does two critical things:

1. Setting a WindowsCompat:
   Drawing your app’s content behind the navigation bars (DecorFitsSystemWindows).

2. Sets the colors of the System Bars.
   Make the navigation bars transparent or matched to the theme of your app.

3. super.onCreate(savedInstanceState)
   From here, Android works on constructing the Activity’s UI components step by step, setting windows and loading layouts right after.

In the case where super.onCreate() is executed first:
Windows are setup generously without the edge to edge applied flags.

Expect awkward empty spaces and reserved cuts due to padding system bars e.g. Surrounding rectangles resulting in negative empty space visually.

Your enableEdgeToEdge() call as the “fix” to the assumed UI redrawing constructed after:
Highlighting the clues of incorrect insets and flickering (UI redrawing irritating).

[imsubhash]

enableEdgeToEdge() is called before super.onCreate() to ensure that the system UI and window insets are configured before the layout is inflated. This guarantees that the system draws your content correctly in relation to edge-to-edge system bars like the status and navigation bars.

If called after super.onCreate(), the window may already be laid out with incorrect insets, leading to layout issues like unexpected padding or content not extending to the edges as intended.

Calling it early allows Android to measure and lay out your views correctly from the start.

Refer official doc - https://developer.android.com/develop/ui/views/layout/edge-to-edge

[JolandaVerhoef]

Closing this issue as it has been answered successfully.