Android toolbar doesn't expand when scrolling up

Question

I have a toolbar that collapses when the RecyclerView scrolls down, but when the user scrolls up quickly, the toolbar doesn't expand. Any idea what is wrong?

This behavior is shown in this video: https://youtu.be/67ntPkW-5XA

Layout code :

<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/coordinator_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">

<android.support.v7.widget.RecyclerView
    android:id="@+id/recycler_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior" />

<android.support.design.widget.AppBarLayout
    android:id="@+id/appbar"
    android:layout_width="match_parent"
    android:layout_height="192dp"
    android:fitsSystemWindows="true"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/toolbar_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true"
        app:layout_scrollFlags="scroll|exitUntilCollapsed">

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

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

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

<android.support.design.widget.FloatingActionButton
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="end|bottom"
    android:layout_margin="16dp"
    android:clickable="true"
    android:onClick="showText"
    android:src="@drawable/ic_done_white_24dp"
    app:borderWidth="0dp" />

Answer 1

If you want it to expand every time you scroll up, you should add app:layout_scrollFlags="scroll|enterAlways" to the view you want to be shown.

As I understand you want to add this to your CollapsingToolbarLayout.

Possible flags:

scroll: this flag should be set for all views that want to scroll off the screen - for views that do not use this flag, they’ll remain pinned to the top of the screen

enterAlways: this flag ensures that any downward scroll will cause this view to become visible, enabling the ‘quick return’ pattern

enterAlwaysCollapsed: When your view has declared a minHeight and you use this flag, your View will only enter at its minimum height (i.e., ‘collapsed’), only re-expanding to its full height when the scrolling view has reached it’s top.

exitUntilCollapsed: this flag causes the view to scroll off until it is ‘collapsed’ (its minHeight) before exiting