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I am working on one android app in which I am using CoordinatorLayout, AppBarLayout and CollapsingToolbarLayout to use the collapse toolbar functionality.

I am using NestedScrollView in layout to expand and collapse AppBarLayout in same layout. When I am trying to scroll up from center of the screen then it does not work but when I try to scroll up screen from right corner of the screen then it scrolls smoothly.

Below mentioned is my xml file

layout.xml

<android.support.v4.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:fillViewport="true"
    android:fitsSystemWindows="true"
    android:paddingBottom="2dp"
    android:paddingLeft="5dp"
    android:paddingRight="5dp"
    android:paddingTop="5dp"
    android:layout_gravity="fill_vertical"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@color/fragment_back_color"
            android:orientation="vertical">


            <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:orientation="horizontal"
                android:padding="5dp">

                <ImageView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center"
                    android:background="@drawable/new_recharge" />

                <com.spiceladdoo.views.RobotTextviewRegular
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center"
                    android:layout_marginLeft="10dp"
                    android:text="NEW PAYMENT"
                    android:textColor="@color/offer_name_text_color" />

            </LinearLayout>


            <RelativeLayout

                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginLeft="5dp"
                android:layout_marginRight="5dp"
                android:background="@color/white"
                android:paddingBottom="20dp"
                android:paddingLeft="10dp"
                android:paddingRight="10dp"
                android:paddingTop="20dp">

                <HorizontalScrollView
                    android:id="@+id/hsv"
                    android:layout_width="fill_parent"
                    android:layout_height="wrap_content"
                    android:layout_alignParentTop="true"
                    android:fillViewport="true"
                    android:measureAllChildren="false"
                    android:scrollbars="none">

                    <LinearLayout
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_centerInParent="true"
                        android:orientation="horizontal">

                        <LinearLayout
                            android:id="@+id/wallet_layout"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:gravity="center"
                            android:orientation="vertical">

                            <ImageView
                                android:id="@+id/wallet_recharge"
                                android:layout_width="wrap_content"
                                android:layout_height="wrap_content"
                                android:layout_gravity="center"
                                android:background="@drawable/wallet_recherge" />

                            <com.spiceladdoo.views.RobotTextviewRegular
                                android:layout_width="65dp"
                                android:layout_height="wrap_content"
                                android:layout_gravity="center"
                                android:layout_marginTop="5dp"
                                android:gravity="center"
                                android:text="WALLET"
                                android:textColor="@color/offer_name_text_color"
                                android:textSize="12sp" />
                            >

                        </LinearLayout>

                        <View
                            android:layout_width="5dp"
                            android:layout_height="20dp"

                            android:background="@color/white" />

                        <LinearLayout
                            android:id="@+id/prepaid_layout"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:gravity="center"
                            android:orientation="vertical">

                            <ImageView
                                android:id="@+id/prepaid_recharge"
                                android:layout_width="wrap_content"
                                android:layout_height="wrap_content"
                                android:layout_gravity="center"
                                android:background="@drawable/prepaid_recherge" />

                            <com.spiceladdoo.views.RobotTextviewRegular
                                android:layout_width="65dp"
                                android:layout_height="wrap_content"
                                android:layout_gravity="center"
                                android:layout_marginTop="5dp"
                                android:gravity="center"
                                android:text="PREPAID"
                                android:textColor="@color/offer_name_text_color"
                                android:textSize="12sp" />
                            >

                        </LinearLayout>

                        <View
                            android:layout_width="5dp"
                            android:layout_height="20dp"

                            android:background="@color/white" />

                        <LinearLayout
                            android:id="@+id/postpaid_layout"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:gravity="center"
                            android:orientation="vertical">

                            <ImageView
                                android:id="@+id/postpaid_recharge"
                                android:layout_width="wrap_content"
                                android:layout_height="wrap_content"
                                android:layout_gravity="center"
                                android:background="@drawable/postpaid_recherge" />

                            <com.spiceladdoo.views.RobotTextviewRegular
                                android:layout_width="65dp"
                                android:layout_height="wrap_content"
                                android:layout_gravity="center"
                                android:layout_marginTop="5dp"
                                android:gravity="center"
                                android:text="POSTPAID"
                                android:textColor="@color/offer_name_text_color"
                                android:textSize="12sp" />
                            >

                        </LinearLayout>

                        <View
                            android:layout_width="5dp"
                            android:layout_height="20dp"
                            android:background="@color/white" />

                        <LinearLayout
                            android:id="@+id/dth_layout"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:gravity="center"
                            android:orientation="vertical">

                            <ImageView
                                android:id="@+id/dth_recharge"
                                android:layout_width="wrap_content"
                                android:layout_height="wrap_content"
                                android:layout_gravity="center"
                                android:background="@drawable/dth_recherge" />

                            <com.spiceladdoo.views.RobotTextviewRegular
                                android:layout_width="65dp"
                                android:layout_height="wrap_content"
                                android:layout_gravity="center"
                                android:layout_marginTop="5dp"
                                android:gravity="center"
                                android:text="DTH"
                                android:textColor="@color/offer_name_text_color"
                                android:textSize="12sp" />
                            >

                        </LinearLayout>

                        <View
                            android:layout_width="5dp"
                            android:layout_height="20dp"
                            android:background="@color/white" />

                        <LinearLayout
                            android:id="@+id/landline_layout"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:gravity="center"
                            android:orientation="vertical">

                            <ImageView
                                android:id="@+id/landline_recharge"
                                android:layout_width="wrap_content"
                                android:layout_height="wrap_content"
                                android:layout_gravity="center"
                                android:background="@drawable/landline_recherge" />

                            <com.spiceladdoo.views.RobotTextviewRegular
                                android:layout_width="65dp"
                                android:layout_height="wrap_content"
                                android:layout_gravity="center"
                                android:layout_marginTop="5dp"
                                android:gravity="center"
                                android:text="LANDLINE"
                                android:textColor="@color/offer_name_text_color"
                                android:textSize="12sp" />
                            >

                        </LinearLayout>

                        <View
                            android:layout_width="5dp"
                            android:layout_height="20dp"
                            android:background="@color/white" />

                        <LinearLayout
                            android:id="@+id/datacard_layout"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:gravity="center"
                            android:orientation="vertical">

                            <ImageView
                                android:id="@+id/datacard_recharge"
                                android:layout_width="wrap_content"
                                android:layout_height="wrap_content"
                                android:layout_gravity="center"
                                android:background="@drawable/datacard_recherge" />

                            <com.spiceladdoo.views.RobotTextviewRegular
                                android:layout_width="65dp"
                                android:layout_height="wrap_content"
                                android:layout_gravity="center"
                                android:layout_marginTop="5dp"
                                android:gravity="center"
                                android:text="DATACARD"
                                android:textColor="@color/offer_name_text_color"
                                android:textSize="12sp" />
                            >

                        </LinearLayout>
                    </LinearLayout>
                </HorizontalScrollView>
            </RelativeLayout>


            <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:orientation="horizontal"

                android:paddingBottom="10dp"
                android:paddingLeft="5dp"
                android:paddingRight="5dp"
                android:paddingTop="10dp">

                <ImageView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center"
                    android:background="@drawable/recent" />

                <com.spiceladdoo.views.RobotTextviewRegular
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center"
                    android:layout_marginLeft="10dp"
                    android:text="RECENT"
                    android:textColor="@color/offer_name_text_color" />

            </LinearLayout>

            <ListView
                android:id="@+id/recent_recharge_list"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_marginLeft="5dp"
                android:layout_marginRight="5dp">

            </ListView>


        </LinearLayout>

        <FrameLayout xmlns:tools="http://schemas.android.com/tools"
            android:id="@+id/recharge_container"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:visibility="visible"
            tools:ignore="MergeRootFrame">

        </FrameLayout>
    </RelativeLayout>
</android.support.v4.widget.NestedScrollView>

The desired result is when I try to scroll up from center of the screen then it should work as smmoth as I scroll up from right corner of the mobile.

Please watch below mentioned video to look at the problem more clearly

https://www.dropbox.com/s/gscfc8vfc7kkpxp/device-2015-12-30-160119.mp4?dl=0

Harry Sharma
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Kushminder Garg
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4 Answers4

36

I believe, I've nailed it:

enter image description here

You can find the source code here - feel free to try;

I took as an example google\designlibdemo.

Here's how my Activity looks like:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/drawer_layout"
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    android:fitsSystemWindows="true">

    <include layout="@layout/include_list_viewpager"/>

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_height="match_parent"
        android:layout_width="wrap_content"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header"
        app:menu="@menu/drawer_view"/>

</android.support.v4.widget.DrawerLayout>

It hosts ViewPager: include_list_viewpager.xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/collapsing_toolbar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_scrollFlags="scroll|enterAlways|snap"
            app:contentScrim="?attr/colorPrimary"
            app:expandedTitleMarginStart="48dp"
            app:expandedTitleMarginEnd="64dp"
            android:fitsSystemWindows="true">
            <ImageView
                android:id="@+id/image"
                android:src="@drawable/header_image"
                android:layout_width="match_parent"
                android:layout_height="200dp"
                android:scaleType="centerCrop"
                android:fitsSystemWindows="true"
                app:layout_collapseMode="parallax"/>
            <View
                android:background="#AA50AA00"
                android:layout_width="match_parent"
                android:layout_height="200dp"
                app:layout_collapseMode="parallax"/>

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:title=""
                android:layout_height="?attr/actionBarSize"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
                app:layout_collapseMode="pin" />

        </android.support.design.widget.CollapsingToolbarLayout>
        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:background="#50AA00"
            app:tabMode="scrollable"
            app:tabIndicatorColor="#FFF"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />
</android.support.design.widget.CoordinatorLayout>

CollapsingToolbarLayout hosts Toolbar (app:layout_collapseMode="pin") and above ImageView (app:layout_collapseMode="parallax").

The hosted in the ViewPager Fragment has this layout:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.NestedScrollView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:fillViewport="true"
    android:fitsSystemWindows="true"
    android:layout_gravity="fill_vertical"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <LinearLayout
        android:orientation="vertical"
        android:background="#DDD"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal"
            android:padding="16dp">
            <ImageView
                android:src="@drawable/mobile"
                android:layout_marginTop="2dp"
                android:layout_width="16dp"
                android:layout_height="16dp" />
            <TextView
                android:text="@string/prepaid_recharge"
                android:layout_marginStart="16dp"
                android:layout_gravity="center_vertical"
                android:textColor="#000"
                android:fontFamily="sans-serif-medium"
                android:textSize="14sp"
                android:textAllCaps="true"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />
        </LinearLayout>
        ........
        <ListView
            android:id="@+id/recent_recharge_list"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>
    </LinearLayout>
</android.support.v4.widget.NestedScrollView>

So it has this behaviour app:layout_behavior="@string/appbar_scrolling_view_behavior" and filling ViewPort (android:fillViewport="true")

And actually - that's all you need. Fragment class is very standard:

public class RechargeFragment extends Fragment {
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.recharge_fragment, container, false);
    }
}

Activity is also remained very standard.

Again, you can find my code example here.

NB! I found it works pretty poor(not smooth at all) on the emulator.

I hope, it helps.

Konstantin Loginov
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  • I have checked your demo project. Scrolling is too slow or sometimes hangs . So not worth to use. – Kushminder Garg Jan 11 '16 at 07:32
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    @KushminderGarg have you checked on the **real** device, not emulator? It works without hanging at all, just as you can see on the gif. (I have similar code in production and no one complained about scrolling yet) – Konstantin Loginov Jan 11 '16 at 07:39
  • I am checking it on real device not on emulator. – Kushminder Garg Jan 11 '16 at 07:48
  • Not smooth at all.It gets stuck. :( which actually brought me back to earth. – Harry Sharma Jun 30 '16 at 09:57
  • Referring to your GIF, would the content inside your Recent Recharge list be scrollable..I am unable to scroll a list inside a view pager which is inside nested scroll view. – eRaisedToX May 04 '17 at 08:47
  • @eRaisedToX - probably, you don't need to nest ViewPager inside scroll view? And make sure that ViewPager has `app:layout_behavior="@string/appbar_scrolling_view_behavior"` property. – Konstantin Loginov May 04 '17 at 09:26
  • I set `app:layout_behavior="@string/appbar_scrolling_view_behavior"` . Actually It did not work earlier because I had fragment layout (frag of view pager) as normal Linear layout but worked when I wrapped that around inside a `nestedscrollview` just like yours.. It worked.. But I still don't understand it fully Anyways ,+1 for good work. – eRaisedToX May 04 '17 at 11:04
  • This doesn't solves the original bug, the accepted answer should be https://stackoverflow.com/questions/31795483/collapsingtoolbarlayout-doesnt-recognize-scroll-fling# making the direct child of NestedScrollView clickable=true – AntPachon May 30 '17 at 13:07
  • I have similar bug, but your solution did not helped me, maby you can help me with it, I have also video and source code with the simplest project: https://stackoverflow.com/questions/50043779/collapsing-appbarlayout-not-scrolling-with-tablayout-and-nestedscrollview – yozhik Apr 27 '18 at 11:27
5

I pretty much had the similar kind of issue when working with the CoordinatorLayout having AppbarLayout ,CollapsingToolbarLayout and NestedScrollView as child views.

The following code is a working piece directly from my project workspace.Hope it helps!! 

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appBar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/collapsing_toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:contentScrim="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">
            <ImageView
                android:id="@+id/cover_pic"
                android:layout_width="match_parent"
                android:layout_height="256dp"
                android:scaleType="centerCrop"
                app:layout_collapseMode="parallax"
                android:src="@drawable/cookin"/>
            <android.support.v7.widget.Toolbar
                android:id="@+id/mToolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
                app:layout_collapseMode="pin"/>

        </android.support.design.widget.CollapsingToolbarLayout>


        <android.support.design.widget.TabLayout
            android:id="@+id/tabLayout"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:layout_gravity="bottom"
            android:background="?attr/colorPrimary"
            app:tabMode="scrollable"/>

    </android.support.design.widget.AppBarLayout>


    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fillViewport="true"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <android.support.v4.view.ViewPager
            android:id="@+id/tab_viewpager"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_behavior="@string/appbar_scrolling_view_behavior" />
    </android.support.v4.widget.NestedScrollView>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <LinearLayout
            android:layout_alignParentBottom="true"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <android.support.design.widget.FloatingActionButton
                android:id="@+id/fab_phone"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="bottom|end"
                android:layout_marginRight="@dimen/fab_margin"
                android:visibility="invisible"
                app:backgroundTint="@color/colorFAB2"
                app:elevation="6dp"
                android:layout_margin="5dp"
                app:pressedTranslationZ="12dp"
                android:src="@drawable/ic_phone_white_24dp" />

            <android.support.design.widget.FloatingActionButton
                android:id="@+id/fab_book"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="bottom|end"
                android:layout_margin="5dp"
                android:layout_marginRight="@dimen/fab_margin"
                android:visibility="invisible"
                app:elevation="6dp"
                app:backgroundTint="@color/colorFAB1"
                app:pressedTranslationZ="12dp"
                android:src="@drawable/ic_receipt_white_24dp" />
            <android.support.design.widget.FloatingActionButton
                android:id="@+id/fab_add"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="bottom|end"
                app:elevation="6dp"
                app:backgroundTint="@color/colorAccent"
                app:pressedTranslationZ="12dp"
                android:layout_margin="@dimen/fab_margin"
                android:src="@drawable/ic_add_white_24dp" />

        </LinearLayout>

    </RelativeLayout>


</android.support.design.widget.CoordinatorLayout>
ishwor kafley
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5

try android:clickable="true" in child view of NestedScrollView Like below:

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fillViewport="true"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical"
            android:clickable="true">
        </LinearLayout>
   </android.support.v4.widget.NestedScrollView>
tahsinRupam
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Yugal Modi
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3

Looks like duplicate of this. Although it points to "solved" thread, the other one is related more to RecyclerView.

I've wrote my behavior based on solutions made by Manolo Garcia and Kirill Boyarshinov from RecyclerView thread. In my case onNestedFling() was not called when making up fling gesture so I hacked onNestedPreScroll(). I've been working inside ViewPager with NestedScroll today, haven't tested below solution in different scenario (although it is based on similar code I wrote for RecyclerView a year ago).

First updated behavior (add it in xml as app:layout_behavior="your.package.FlingBehavior"> for android.support.design.widget.AppBarLayout):

public final class FlingBehavior extends AppBarLayout.Behavior {

    private static final String TAG = FlingBehavior.class.getName();
    private static final int TOP_CHILD_FLING_THRESHOLD = 1;
    private static final float OPTIMAL_FLING_VELOCITY = 3500;
    private static final float MIN_FLING_VELOCITY = 20;

    boolean shouldFling = false;
    float flingVelocityY = 0;

    public FlingBehavior() {
    }

    public FlingBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, AppBarLayout child, View target,
                                  int velocityX, int velocityY, int[] consumed) {

        super.onNestedPreScroll(coordinatorLayout, child, target, velocityX, velocityY, consumed);

        if (velocityY > MIN_FLING_VELOCITY) {
            shouldFling = true;
            flingVelocityY = velocityY;
        } else {
            shouldFling = false;
        }
    }

    @Override
    public void onStopNestedScroll(CoordinatorLayout coordinatorLayout, AppBarLayout abl, View target) {
        super.onStopNestedScroll(coordinatorLayout, abl, target);
        if (shouldFling) {
            Log.d(TAG, "onNestedPreScroll: running nested fling, velocityY is " + flingVelocityY);
            onNestedFling(coordinatorLayout, abl, target, 0, flingVelocityY, true);
        }
    }

    @Override
    public boolean onNestedFling(CoordinatorLayout coordinatorLayout, AppBarLayout child, View target,
                                 float velocityX, float velocityY, boolean consumed) {

        if (target instanceof RecyclerView && velocityY < 0) {
            Log.d(TAG, "onNestedFling: target is recyclerView");
            final RecyclerView recyclerView = (RecyclerView) target;
            final View firstChild = recyclerView.getChildAt(0);
            final int childAdapterPosition = recyclerView.getChildAdapterPosition(firstChild);
            consumed = childAdapterPosition > TOP_CHILD_FLING_THRESHOLD;
        }

        // prevent fling flickering when going up
        if (target instanceof NestedScrollView && velocityY > 0) {
            consumed = true;
        }

        if (Math.abs(velocityY) < OPTIMAL_FLING_VELOCITY) {
            velocityY = OPTIMAL_FLING_VELOCITY * (velocityY < 0 ? -1 : 1);
        }
        Log.d(TAG, "onNestedFling: velocityY - " + velocityY + ", consumed - " + consumed);

        return super.onNestedFling(coordinatorLayout, child, target, velocityX, velocityY, consumed);
    }
}

Now it should scroll smoothly but content of NestedScrollView (and RecyclerView) can scroll before AppBarLayout is collapsed, which can look wierd. To solve it follow this answer. Make small change to use fullScroll(ScrollView.FOCUS_UP) method instead of scrollTo(0, 0) otherwise You may notice small flickering during fast scrolls, here:

AppBarLayout appBarLayout = findViewById(...);
appBarLayout.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() {
            @Override
            public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
                shouldScroll = Math.abs(verticalOffset) == appBarLayout.getTotalScrollRange();
            }
        });
NestedScrollView nestedScrollView = findViewById(...);
nestedScrollView.setOnScrollChangeListener(new NestedScrollView.OnScrollChangeListener() {
            @Override
            public void onScrollChange(NestedScrollView v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
                if (!shouldScroll)
                    nestedScrollView.fullScroll(ScrollView.FOCUS_UP);
            }
        });

After that I called it an end, but You may want to proceed further to make it scroll even more smoothly like in Google Play, there is (I think unsolved) thread about it here.

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Darek Deoniziak
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  • This is a good solution, but for some reason the NestedScrollView.OnScrollChangeListener is never triggered during a scroll event. Any idea why that could be? I use `app:layout_behavior="@string/appbar_scrolling_view_behavior"` on the scroll view, but it seems not to work with/without it. – Vlad Apr 25 '17 at 19:00
  • Are you sure that event is not triggered? Nowadays in AS debug seems to not always work for me, same for log. I know that might be crazy suggestion, but try to add Toast in event and build it once to test if toast is displayed. If above will not work then perhaps something might be wrong with Your layout xml? It should look more or less like this one: https://pastebin.com/Wcrrv8rC – Darek Deoniziak Apr 27 '17 at 06:25