向下滚动时，工具栏不会同时进入ListView

Question

我试图制作一个具有Play商店/ WhatsApp的滚动效果（折叠栏？）的工具栏：当列表向上滚动时，工具栏隐藏，而TabLayout保持可见，然后向下滚动列表时，工具栏应在与ListView相同的位置滚动。

示例：https://imgur.com/CZ4KjmZ

我的：https://imgur.com/FuG0zdx

编辑：向上滚动时，工具栏会留一个空白：        https://imgur.com/w4S0KiX

---

布局

<android.support.design.widget.CoordinatorLayout   
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">


    <android.support.design.widget.AppBarLayout
        android:elevation="0dp"
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/ThemeOverlay.AppCompat.Dark"
        android:fitsSystemWindows="true"
        >

        <android.support.design.widget.CollapsingToolbarLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:minHeight="50dp"
            app:layout_behavior="com.github.godness84.
               appbarsnapbehavior.AppBarSnapBehavior"
            app:layout_scrollFlags="scroll|enterAlways|snap"
            app:titleEnabled="false">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="56dp"
                android:orientation="vertical">

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

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

        <LinearLayout
            android:id="@+id/tab_layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom"
            android:background="@color/colorPrimary"
            android:orientation="vertical">

            <android.support.design.widget.TabLayout
                android:id="@+id/tabs"
                app:tabMode="scrollable"
                android:layout_width="match_parent"
                android:layout_height="50dp"
                app:tabIndicatorColor="@color/colorPrimaryDark"
                app:tabSelectedTextColor="#fff"
                app:tabTextColor="@color/colorPrimaryDark">

                <android.support.design.widget.TabItem
                    android:id="@+id/tabItemProdotti"
                    android:layout_height="wrap_content"
                    android:text="Prodotti"
                    android:layout_width="wrap_content" />

                <android.support.design.widget.TabItem
                    android:id="@+id/tabItemCantieri"
                    android:layout_height="wrap_content"
                    android:text="Cantieri"
                    android:layout_width="wrap_content"/>

                <android.support.design.widget.TabItem
                    android:id="@+id/tabClienti"
                    android:layout_height="wrap_content"
                    android:text="Clienti"
                    android:layout_width="wrap_content"/>

                <android.support.design.widget.TabItem
                    android:id="@+id/tabItemImpostazioni"
                    android:text="Impostazioni"
                    android:layout_height="wrap_content"
                    android:layout_width="wrap_content"/>

                <android.support.design.widget.TabItem
                    android:id="@+id/tabItemCredits"
                    android:layout_height="wrap_content"
                    android:text="Credits"
                    android:layout_width="wrap_content"/>

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

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

<android.support.v4.view.ViewPager
   app:layout_behavior="com.github.godness84.
     appbarsnapbehavior.ScrollingViewBehavior"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    />

---

工具栏

<android.support.v7.widget.Toolbar android:id="@+id/toolbarHome"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_alignParentTop="true"
   android:layout_width="match_parent"
   android:layout_height="?attr/actionBarSize"
   android:background="@color/colorPrimary"
   app:titleTextColor="@color/white"
   app:title="@string/app_name">

</android.support.v7.widget.Toolbar>