Develop Reference

Scrim color change callback on CollapsingToolbarLayout?

Problem
Given the following view hierarchy
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/coordinator_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.google.android.material.appbar.AppBarLayout
android:id="#+id/app_bar_layout"
android:layout_width="match_parent"
android:layout_height="96dp"
android:backgroundTint="?android:colorBackground">
<com.google.android.material.appbar.CollapsingToolbarLayout
android:id="#+id/collapsing_toolbar_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:collapsedTitleGravity="start"
app:collapsedTitleTextAppearance="?textAppearanceHeadline6"
app:contentScrim="?colorSurface"
app:expandedTitleGravity="start|bottom"
app:expandedTitleMarginBottom="16dp"
app:expandedTitleMarginEnd="16dp"
app:expandedTitleMarginStart="16dp"
app:expandedTitleTextAppearance="?textAppearanceHeadline5"
app:layout_scrollFlags="scroll|exitUntilCollapsed"
app:statusBarScrim="?android:colorBackground"
app:toolbarId="#+id/toolbar">
<com.google.android.material.appbar.MaterialToolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?actionBarSize"
android:background="#null"
app:layout_collapseMode="pin" />
</com.google.android.material.appbar.CollapsingToolbarLayout>
</com.google.android.material.appbar.AppBarLayout>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/menu_section_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
When a user scrolls the list
Then status bar background color should change as per the top navigation bar's background at-least in expanded and collapsed state.
Current Solution
Implement a custom OnOffsetChangedListener
internal abstract class AppBarLayoutOffsetStateChangeListener : AppBarLayout.OnOffsetChangedListener {
enum class State {
COLLAPSED, EXPANDED, SCROLLING
}
private var postJob: Runnable? = null
abstract fun onStateChange(state: State)
override fun onOffsetChanged(appBarLayout: AppBarLayout, verticalOffset: Int) {
if (abs(verticalOffset) - appBarLayout.totalScrollRange == 0) {
postJob = Runnable {
onStateChange(State.COLLAPSED)
}
appBarLayout.postDelayed(postJob, DELAY_COLLAPSED_STATE)
} else if (verticalOffset == 0) {
onStateChange(State.EXPANDED)
} else {
onStateChange(State.SCROLLING)
postJob?.let {
appBarLayout.removeCallbacks(it)
postJob = null
}
}
}
private companion object {
const val DELAY_COLLAPSED_STATE = 1000L // in ms.
}
}
Set an instance of AppBarLayoutOffsetStateChangeListener to AppBarLayout
appBarLayout.addOnOffsetChangedListener(object : AppBarLayoutOffsetStateChangeListener() {
override fun onStateChange(state: State) {
when (state) {
State.EXPANDED -> {
// set status bar color to `AppBarLayout` background tint.
}
State.COLLAPSED -> {
// set status bar color to `CollapsingToolbarLayout` content scrim color
}
else -> Unit
}
}
})
Rough edges
CollapsingToolbarLayout color animate changes independently of AppBarLayout vertical offset, so had to add DELAY_COLLAPSED_STATE of 1 second ! just to synchronize the two animations.
Status bar colors in Expanded and Collapsed states are picked from two different views, after cross-checking using Layout Inspector.
Question to the community
Is there a better solution ?

How do I achieve on scroll behavior where both the toolbar and bottom navigation should hide?Only one of them is working

I am trying to achieve the coordinator layout behaviour where on scrolling the recycler view can hide both the toolbar and bottom navigation view. So far I have achieved one success i.e bottom navigation bottom bar does hide but with one caveat that it remains active even when the keyboard is on(how do I fix that too?)
My main concern here is how do I achieve the same feature of bottom navigation view of hiding into the toolbar?
I have included the custom toolbar in Appbar layout, but I have tried to add the Toolbar layout tag too in the AppBar nothing works, It just remains the same.
And for the bottomnavigation jumping up on top I don't know what to do? till now I have added snap scroll flags on the bottomnavigation view to stop this behaviour and also snap flag didn't work, I think so, coz it remains in halfway position while going up on search tap.
Got this BottomNavigationBehavior from the wonderful article.
reference
video showing behavior
image for snap behavior
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="match_parent"
android:layout_width="match_parent"
>
<com.google.android.material.appbar.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="?actionBarSize"
app:elevation="0dp"
android:background="#android:color/transparent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
>
<include
app:layout_scrollFlags="scroll|enterAlways|snap"
layout="#layout/browser_search_tap_tb"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/browser_tb"
/>
</com.google.android.material.appbar.AppBarLayout>
<!--Scrolling effect for the bottom nav menu-->
<androidx.recyclerview.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:listitem="#layout/rv_test_items"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
android:id="#+id/rv_test"
/>
<!--Bottom navigation view for the Selection of the Tabs and Items in Menu-->
<com.google.android.material.bottomnavigation.BottomNavigationView
app:layout_scrollFlags="scroll|enterAlways|snap"
android:id="#+id/browser_bottom_nav_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:background="#ffff"
app:layout_behavior="com.example.android.browserui.BottomNavigationBehavior"
app:labelVisibilityMode="unlabeled"
app:menu="#menu/bottom_nav_menu"
/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
browser_search_tap_tb.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.appcompat.widget.Toolbar
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="?actionBarSize"
android:background="#android:color/transparent"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="#style/ThemeOverlay.AppCompat"
app:contentInsetStart="8dp"
app:contentInsetEnd="8dp"
>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:layout_width="0dp"
android:layout_height="match_parent"
android:hint="Search or type new address"
android:padding="8dp"
android:paddingEnd="12dp"
android:paddingStart="12dp"
android:drawableEnd="#drawable/ic_mic"
android:inputType="textWebEditText"
android:background="#drawable/rounded_et_search"
app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent" android:id="#+id/et_search_bar_tap"
app:layout_constraintEnd_toEndOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.appcompat.widget.Toolbar>
BottomNavigationBehavior.kt
class BottomNavigationBehavior<V : View>(context: Context, attrs: AttributeSet) :
CoordinatorLayout.Behavior<V>(context, attrs) {
private var lastStartedType: Int = 0
private var offsetAnimator: ValueAnimator? = null
var isSnappingEnabled = false
override fun layoutDependsOn(parent: CoordinatorLayout, child: V, dependency: View): Boolean {
if (dependency is Snackbar.SnackbarLayout) {
updateSnackbar(child, dependency)
}
return super.layoutDependsOn(parent, child, dependency)
}
override fun onStartNestedScroll(
coordinatorLayout: CoordinatorLayout, child: V, directTargetChild: View, target: View, axes: Int, type: Int
): Boolean {
if (axes != ViewCompat.SCROLL_AXIS_VERTICAL)
return false
lastStartedType = type
offsetAnimator?.cancel()
return true
}
override fun onNestedPreScroll(
coordinatorLayout: CoordinatorLayout, child: V, target: View, dx: Int, dy: Int, consumed: IntArray, type: Int
) {
super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed, type)
child.translationY = max(0f, min(child.height.toFloat(), child.translationY + dy))
}
override fun onStopNestedScroll(coordinatorLayout: CoordinatorLayout, child: V, target: View, type: Int) {
if (!isSnappingEnabled)
return
// add snap behaviour
// Logic here borrowed from AppBarLayout onStopNestedScroll code
if (lastStartedType == ViewCompat.TYPE_TOUCH || type == ViewCompat.TYPE_NON_TOUCH) {
// find nearest seam
val currTranslation = child.translationY
val childHalfHeight = child.height * 0.5f
// translate down
if (currTranslation >= childHalfHeight) {
animateBarVisibility(child, isVisible = false)
}
// translate up
else {
animateBarVisibility(child, isVisible = true)
}
}
}
private fun animateBarVisibility(child: View, isVisible: Boolean) {
if (offsetAnimator == null) {
offsetAnimator = ValueAnimator().apply {
interpolator = DecelerateInterpolator()
duration = 150L
}
offsetAnimator?.addUpdateListener {
child.translationY = it.animatedValue as Float
}
} else {
offsetAnimator?.cancel()
}
val targetTranslation = if (isVisible) 0f else child.height.toFloat()
offsetAnimator?.setFloatValues(child.translationY, targetTranslation)
offsetAnimator?.start()
}
private fun updateSnackbar(child: View, snackbarLayout: Snackbar.SnackbarLayout) {
if (snackbarLayout.layoutParams is CoordinatorLayout.LayoutParams) {
val params = snackbarLayout.layoutParams as CoordinatorLayout.LayoutParams
params.anchorId = child.id
params.anchorGravity = Gravity.TOP
params.gravity = Gravity.TOP
snackbarLayout.layoutParams = params
}
}
}

So Finally Resolved My issue after getting my head around for 4 days here are some changes which I did and solved the issues :
activity_main.xml
<com.google.android.material.appbar.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="?actionBarSize"
app:elevation="0dp"
android:background="#android:color/transparent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"<!--Removed this line-->
>
<!--Bottom navigation view for the Selection of the Tabs and Items in Menu-->
<com.google.android.material.bottomnavigation.BottomNavigationView
app:layout_scrollFlags="scroll|enterAlways|snap"<!--Removed this line-->
android:id="#+id/browser_bottom_nav_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:background="#ffff"
app:layout_behavior="com.example.android.browserui.BottomNavigationBehavior"
app:labelVisibilityMode="unlabeled"
app:menu="#menu/bottom_nav_menu"
/>
Here in activity_main.xml, I removed the layout_behavior because the appbar itself is invoking the scroll behavior for other layout items, it acts as a parent.
app:layout_behavior="#string/appbar_scrolling_view_behavior"
Also removed scrollflags from the bottom navigation view, AS I was implementing this behavior from the Class BottomNavigationBehavior.kt, You find the implementation below
app:layout_scrollFlags="scroll|enterAlways|snap"
browser_search_tap_tb.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.appcompat.widget.Toolbar
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="?actionBarSize"
android:background="#android:color/transparent"
app:layout_scrollFlags="scroll|enterAlways" <!--Removed this line-->
app:popupTheme="#style/ThemeOverlay.AppCompat"
app:contentInsetStart="8dp"
app:contentInsetEnd="8dp"
>
Here in browser_search_tb, I removed the following line because it was overriding the Scrollflags in co-ordinator layout so removed it and it worked flawlessly
app:layout_scrollFlags="scroll|enterAlways"
BottomNavigationBehavior.kt
override fun onStopNestedScroll(coordinatorLayout: CoordinatorLayout, child: V, target: View, type: Int) {
if (!isSnappingEnabled)
return // removed this line
{
// add snap behaviour
// Logic here borrowed from AppBarLayout onStopNestedScroll code
if (lastStartedType == ViewCompat.TYPE_TOUCH || type == ViewCompat.TYPE_NON_TOUCH) {
// find nearest seam
val currTranslation = child.translationY
val childHalfHeight = child.height * 0.5f
// translate down
if (currTranslation >= childHalfHeight) {
animateBarVisibility(child, isVisible = false)
}
// translate up
else {
animateBarVisibility(child, isVisible = true)
}
}
}
}
Here I removed the
return
and added braces{} to the if statement and snap feature did work properly
Hope this answer will help you and will cut down your debugging time.
The above reference is one of the best article you can find for scrolling behavior on the internet it simple and smooth to grasp

How to hide the Floating Action Button from Bottom App Bar Layout

I'm creating a Bottom App Bar with an Floating Action Button. The App Bar is part of my Main Activity and I want to hide the FAB for some Fragments within the Activity.
I already tried 'View.GONE' and 'fab.hide()'. Then I tried to hide the Fab with following function:
private fun hideFloatingActionButton() {
val params = fab.layoutParams as CoordinatorLayout.LayoutParams
val behavior = params.behavior as FloatingActionButton.Behavior?
if (behavior != null) {
behavior.isAutoHideEnabled = false
}
params.anchorId = View.NO_ID;
params.width = 0;
params.height = 0;
fab.layoutParams = params
fab.hide()
}
My layout.xml:
<androidx.coordinatorlayout.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
tools:context=".MainActivity"
android:background="#color/backPrimary"
android:layout_width="match_parent"
android:layout_height="match_parent">
...
content
...
<com.google.android.material.bottomappbar.BottomAppBar
android:id="#+id/bar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
style="#style/Widget.MaterialComponents.BottomAppBar"
app:navigationIcon="#drawable/ic_burger_menu"
app:fabAlignmentMode="end"
/>
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/start_project_day"
app:srcCompat="#drawable/ic_next"
app:layout_anchor="#id/bar"
/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

Just tested out with fab.hide() method and it works. The "logic" to hide the fab should occur in the activity and not in the fragment. The next logic is set in the activity and the hide part is inside the else branch at the end.
navController.addOnDestinationChangedListener { controller, destination, _ ->
bar.animate().translationY(0f)
// First page is main menu
if(controller.graph.startDestination == destination.id){
bar.navigationIcon = icon
bar.fabAlignmentMode = BottomAppBar.FAB_ALIGNMENT_MODE_CENTER
fab?.setImageDrawable(getDrawable(R.drawable.ic_local_wtf))
}else{
// Hide navigation drawer icon
bar.navigationIcon = null
// Move FAB from the center of BottomAppBar to the end of it
bar.fabAlignmentMode = BottomAppBar.FAB_ALIGNMENT_MODE_END
// Replace the action menu
//bar.replaceMenu(bottomappbar_menu_secondary)
invalidateOptionsMenu()
// Change FAB icon
fab?.setImageDrawable(getDrawable(R.drawable.ic_reply_white_24dp))
fab.hide()
}
}

RecyclerView in BottomSheet not working as expected

I have a problem with RecyclerView directly inside of layout with bottomsheetbehaviour. The problem is that when bottom sheet is expanded and content is scrolled down, when I go to scroll back up it causes Bottom Sheet to start collapsing, instead of RecyclerView first being scrolled back to top.
Here's a video to demonstrate the problem. As you can see the problem appears when I scroll down on expanded bottom sheet. It immediately start to collapse instead of "waiting" for RecyclerView to scroll to top first.
Here is my layout code
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:id="#+id/scheduleRoot"
android:layout_height="match_parent"
tools:context=".schedule.ScheduleFragment">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/scheduleSheet"
app:behavior_peekHeight="300dp"
android:elevation="16dp"
android:clickable="false"
android:focusable="false"
android:background="#drawable/bg_bottom_sheet"
app:layout_behavior="com.google.android.material.bottomsheet.BottomSheetBehavior">
<androidx.recyclerview.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/scheduleRecyclerView"
android:clickable="true"
android:focusable="true"
android:layout_marginTop="8dp"/>
</LinearLayout>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
Any help is appreciated!

I just encountered same problem, but I fixed it by adding this to onCreate:
androidx.core.view.ViewCompat.setNestedScrollingEnabled(recyclerview, false);

Add
android:nestedScrollingEnabled="true"
in the root layout of BottomSheetDialogFragment.

I had similar issue: Maybe the solution to my problem will give you some ideas. My bottom sheet was expanded to full height with recycler view in it; the bottom sheet was collapsing on user-drag, even though the first item in recycler view wasn't visible yet.
So, what I did:
You can enable/disable bottom sheet dragging by "isDraggable" = true/false
Add OnScrollListener for recycler view.
Override onScrolled and check layoutManager.findFirstVisibleItemPosition() in it
If first item is visible - update bottom sheet behavior.isDraggable = true, i also added small delay before setting behavior.isDraggable = true, because bottom sheet was collapsing too fast, but you might not need it
Maybe it's not optimal but it was fitting my needs and maybe will help you.

Your recyclerview item has overighted the scrolling state, so this error generates. The layout you provided does not have enough data to determine the cause. You change the item is a unique view to check

I played with this for a long time and tried way too many solutions. For me, this worked best:
val layoutManager = LinearLayoutManager(requireContext())
binding.recyclerView.layoutManager = layoutManager
binding.recyclerView.setOnScrollChangeListener { _, _, _, _, _ ->
if (bottomSheetBehavior.state == BottomSheetBehavior.STATE_EXPANDED) {
bottomSheetBehavior.isDraggable = layoutManager.findFirstCompletelyVisibleItemPosition() == 0
} else {
bottomSheetBehavior.isDraggable = true
}
}
The key to the solution is is controlling users ability drag the bottom sheet while the recyclerview is partially scrolled. The method only allows scrolling again once the top most cell is fully visible.
Its not ideal as the user may want to grab the very top of the bottom sheet (assuming its not part of the recycler view) and dismiss the bottom sheet regardless of its scroll position. Im just accepting.
Whatever you do, do not try these, as they just disable any recycling functionality and all cells are loaded at instantiation having a really bad impact on performance:
wrap_content
or:
binding.recyclerView.isNestedScrollingEnabled = false

Enable the scroll state of BottomSheet to allow scroll if recyclerview 0th item is visible.
activity_main.xml
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools">
<data />
<androidx.coordinatorlayout.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#A8A7A7"
tools:context=".MainActivity">
<LinearLayout
android:id="#+id/parent"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#fff"
android:orientation="vertical"
app:behavior_hideable="true"
app:behavior_peekHeight="80dp"
app:layout_behavior="com.asadmukhtar.recyclerviewinsidebottomsheet.LockableBottomSheetBehavior"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="10dp"
android:gravity="center"
android:text="Drag Me"
android:textColor="#000"
android:textSize="20sp"
android:textStyle="bold" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rv_items"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
</layout>
LockableBottomSheet file that used for handling allow dragging option or not.
class LockableBottomSheetBehavior<V : View?> : BottomSheetBehavior<V> {
private var mAllowUserDragging = true
constructor()
constructor(context: Context, attrs: AttributeSet?) : super(
context,
attrs
)
fun setAllowUserDragging(allowUserDragging: Boolean) {
mAllowUserDragging = allowUserDragging
}
override fun onInterceptTouchEvent(
parent: CoordinatorLayout,
child: V,
event: MotionEvent
): Boolean {
return if (!mAllowUserDragging) {
false
} else super.onInterceptTouchEvent(parent, child, event)
}
}
MainActivity.java
var bottomSheetBehavior: LockableBottomSheetBehavior<*>? = null
lateinit var binding: ActivityMainBinding
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding =
DataBindingUtil.setContentView(this, R.layout.activity_main)
setUpBottomSheetBehaviour()
binding.rvItems.layoutManager = LinearLayoutManager(this)
binding.rvItems.adapter = RecyclerViewAdapter(this)
binding.rvItems.addOnScrollListener(object : RecyclerView.OnScrollListener() {
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
super.onScrollStateChanged(recyclerView, newState)
val firstPosition = (binding.rvItems.layoutManager as LinearLayoutManager)
.findFirstVisibleItemPosition()
updateBottomSheetLockState(firstPosition == 0)
}
})
}
fun updateBottomSheetLockState(allow: Boolean) {
bottomSheetBehavior?.setAllowUserDragging(allow)
}
fun updateBottomSheetState(state: Int) {
if (bottomSheetBehavior != null) {
bottomSheetBehavior?.state = state
}
}
private fun setUpBottomSheetBehaviour() {
val bottomSheetBehavior: BottomSheetBehavior<LinearLayout> =
BottomSheetBehavior.from(binding.parent)
this.bottomSheetBehavior = bottomSheetBehavior as LockableBottomSheetBehavior<*>
updateBottomSheetState(BottomSheetBehavior.STATE_COLLAPSED)
}

Your implementation might need more coding and with the provided code we might not able to give you good feedback.
Try this documentation
https://material.io/develop/android/components/bottom-sheet-behavior/
Plus I found this another implementation.
https://www.youtube.com/watch?v=WeaylHAwIIk

How i can set Half Expanded state for my BottomSheet

I have layout with bottom sheet.
<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/coordinator_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.google.android.material.appbar.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar">
<com.google.android.material.appbar.CollapsingToolbarLayout
android:id="#+id/collapsing_toolbar"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:contentScrim="#color/colorPrimary"
app:layout_scrollFlags="scroll|exitUntilCollapsed" />
</com.google.android.material.appbar.AppBarLayout>
<include layout="#layout/content_main_weather_map" />
<include layout="#layout/bottom_sheet" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>
Bottom sheet layout
<?xml version="1.0" encoding="utf-8"?>
<androidx.core.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/bottom_sheet"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/white"
android:clipToPadding="true"
app:behavior_peekHeight="80dp"
app:layout_behavior="#string/bottom_sheet_behavior">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/weather_recycler"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
tools:listitem="#layout/item_weather" />
</LinearLayout>
</androidx.core.widget.NestedScrollView>
It is necessary for me that my bottom sheet opens first half, and after re-dragging it opens to full screen. How is it done in google maps app. But I have no idea how to do this.

It is better to use the framework with its full potential. As official documentation states for method setFitToContents :
Sets whether the height of the expanded sheet is determined by the height of its contents, or if it is expanded in two stages (half the height of the parent
container, full height of parent container). Default value is true.
So all you need is set setFitToContent to false with:
behavior = BottomSheetBehavior.from(your_bottom_sheet_xml)
behavior.isFitToContents = false
behavior.halfExpandedRatio = 0.6f
With this 3-line-code the bottom sheet will expand till 60% of the screen at first, and afterwards it will fully expand to 100%.
Hope it helps!

Just set BottomSheetBehaivor state to BottomSheetBehavior.STATE_HALF_EXPANDED.
Also if you need after full expanding let user again go back to half expanded mode, you need to set peek height to half of window height.
val bottomSheetBehavior = BottomSheetBehavior.from<NestedScrollView>(bottom_sheet)
val metrics = resources.displayMetrics
bottomSheetBehavior.peekHeight = metrics.heightPixels / 2
bottomSheetBehavior.state = BottomSheetBehavior.STATE_HALF_EXPANDED

I have tried the #Massab and #HeyAlex but didn't match my desired behavior.
With the following solution in kotlin, if your bottomsheet sliding is near the expanded state, it stays expanded, if is near the half state, stays at half and if it's near collapsed, it stays collapsed:
val bottomSheet = view.findViewById<View>(R.id.bottom_sheet1)
val mBottomSheetBehavior = BottomSheetBehavior.from(bottomSheet)
mBottomSheetBehavior.state = BottomSheetBehavior.STATE_COLLAPSED
mBottomSheetBehavior.addBottomSheetCallback(object: BottomSheetBehavior.BottomSheetCallback(){
override fun onStateChanged(bottomSheet: View, newState: Int) {
}
override fun onSlide(bottomSheet: View, slideOffset: Float) {
val upperState = 0.66
val lowerState = 0.33
if (bottomSheetEventsFilterBehavior.state == BottomSheetBehavior.STATE_SETTLING ) {
if(slideOffset >= upperState){
mBottomSheetBehavior.state = BottomSheetBehavior.STATE_EXPANDED
}
if(slideOffset > lowerState && slideOffset < upperState){
mBottomSheetBehavior.state = BottomSheetBehavior.STATE_HALF_EXPANDED
}
if(slideOffset <= lowerState){
mBottomSheetBehavior.state = BottomSheetBehavior.STATE_COLLAPSED
}
}
}
})

Although this question has been answered, but just got another way to implement this behavior so sharing for others.
Create a global variable and initialize it with the default state of your BottomSheetBehavior, like
int state = BottomSheetBehavior.STATE_COLLAPSED;
Then, in BottomSheetBehavior.BottomSheetCallback update your state variable to the current state
and in
BottomSheetBehavior.STATE_DRAGGING, if state is not half expanded,
set the state to BottomSheetBehavior.STATE_HALF_EXPANDED
sheetBehavior.setBottomSheetCallback(new BottomSheetBehavior.BottomSheetCallback() {
#Override
public void onStateChanged(#NonNull View view, int i) {
switch (i) {
case BottomSheetBehavior.STATE_COLLAPSED:
state = BottomSheetBehavior.STATE_COLLAPSED;
binder.imgRefresh.setVisibility(View.GONE);
break;
case BottomSheetBehavior.STATE_EXPANDED:
binder.imgRefresh.setVisibility(View.VISIBLE);
state = BottomSheetBehavior.STATE_EXPANDED;
break;
case BottomSheetBehavior.STATE_DRAGGING:
if (state != BottomSheetBehavior.STATE_HALF_EXPANDED) {
sheetBehavior.setState(BottomSheetBehavior.STATE_HALF_EXPANDED);
}
break;
case BottomSheetBehavior.STATE_HALF_EXPANDED:
state = BottomSheetBehavior.STATE_HALF_EXPANDED;
break;
}
}
#Override
public void onSlide(#NonNull View view, float v) {
binder.viewExtender.setAlpha(1 - v);
}
});
This will make your BottomSheet to take three steps , i.e., Collapsed, Half Expanded, Expanded.
Hope it can help someone!

class BottomSheetFragment : BottomSheetDialogFragment() {
/* inside of your Bottom Sheet Dialog Fragment */
override fun onStart() {
super.onStart()
BottomSheetBehavior.from(requireView().parent as View).apply {
state = BottomSheetBehavior.STATE_HALF_EXPANDED
}
}
}

Use this block in onCreateView before returning root view
dialog!!.setOnShowListener { dialog ->
val d = dialog as BottomSheetDialog
BottomSheetBehavior.from(requireView().parent as View).apply {
state = BottomSheetBehavior.STATE_EXPANDED
}
}