[BottomSheetDialogFragment] What's the recommended way to customize the behavior of a BottomSheetDialogFragment?

Let’s say I want my bottom sheet to skip its collapsed state. If I used a BottomSheetBehavior I could just set skipCollapse to true. What’s the recommended way to achieve that on a BottomSheetDialogFragment?

So far, I’ve been retrieving and modifying the BottomSheetDialogFragment’s inner BottomSheetBehavior myself, like so:

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        dialog?.setOnShowListener { dialogInterface ->
            val sheetDialog = dialogInterface as? BottomSheetDialog

            val bottomSheet = sheetDialog?.findViewById<FrameLayout>(
                    com.google.android.material.R.id.design_bottom_sheet
            )

            bottomSheet?.let {
                val behavior = BottomSheetBehavior.from(it)
                behavior.skipCollapsed = true
                // any other behavior modification here
            }
        }
    }

However, this approach seems kind of hackish to me. Is there any alternative or is this the recommended way to achieve what I want?

[iRYO400]

I’ve found a convenient way to config bottom sheet behavior using styles.

1. Customize default BottomSheet by overriding it’s attributes, for example in styles.xml

    <style name="Widget.MyApp.BottomSheet.Modal" parent="Widget.MaterialComponents.BottomSheet.Modal">
        <item name="behavior_skipCollapsed">true</item>
        <item name="behavior_fitToContents">true</item>
        <item name="behavior_peekHeight">1000dp</item> // yep, that helped to skip collapsed state at initial
        <item name="behavior_hideable">true</item>
    </style>

Go inside Widget.MaterialComponents.BottomSheet.Modal to see what settings you can modify.

1. Then create custom theme inherited from Theme.Design.BottomSheetDialog and set that you want to override bottom sheet’s style with you own. Also can be placed in styles.xml

    <style name="Theme.MyApp.BottomSheetDialog" parent="Theme.Design.BottomSheetDialog">
        <item name="bottomSheetStyle">@style/Widget.MyApp.BottomSheet.Modal</item>
    </style>

1. And the last, define your new created theme for bottom sheet dialog in your Activity’s theme or Application’s theme, which placed in themes.xml(hope you follow Google’s recommendations about packaging styles&themes)

<style name="Base.Theme.MyApp" parent="Base.Theme.Root">
    ... too many other things
    <item name="bottomSheetDialogTheme">@style/Theme.MyApp.BottomSheetDialog</item>
</style>

[xanscale]

@renanferrari inside onViewCreated i used that

val behavior: BottomSheetBehavior<*> = (dialog as BottomSheetDialog).behavior
behavior.halfExpandedRatio = 0.3f
behavior.state = BottomSheetBehavior.STATE_HALF_EXPANDED

i don’t know if it is the correct way