Hiding AppBarLayout on RecyclerView Scroll using MaterialDesignComponents

Question

I'm trying to collapse the AppBarLayout when I scroll up the RecyclerView. I'm trying this using Material Design Components.

So here's my code:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <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" app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent">
        <com.google.android.material.appbar.MaterialToolbar
            android:layout_height="?attr/actionBarSize"
            android:layout_width="match_parent"
            android:id="@+id/toolbar"
            app:layout_scrollFlags="scroll|enterAlways|snap"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light">
            <com.google.android.material.textview.MaterialTextView
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:gravity="center"
                android:textSize="18sp"
                android:text="@string/app_name"/>
        </com.google.android.material.appbar.MaterialToolbar>
    </com.google.android.material.appbar.AppBarLayout>

    <androidx.recyclerview.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/component_recycler_view"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"/>

    <com.google.android.material.floatingactionbutton.ExtendedFloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="24dp"
        android:layout_gravity="bottom|end"
        android:contentDescription="@string/extended_fab_content_desc"
        android:text="@string/extended_fab_label"
        app:icon="@drawable/ic_plus_24dp"
        app:layout_anchor="@id/component_recycler_view"
        app:layout_anchorGravity="bottom|right|end"
        app:layout_constraintEnd_toEndOf="parent"
        android:layout_marginEnd="24dp"
        android:layout_marginBottom="24dp"
        app:layout_constraintBottom_toBottomOf="@id/component_recycler_view"/>

</androidx.constraintlayout.widget.ConstraintLayout>

When I scroll up on the recyclerview, it does scroll up but the appbarlayout does not hide itself. Moreover the topmost item of the RecyclerView is partially hidden behind the AppBarLayout.

Answer 1

You can use CoordinatorLayout to achieve a CollapsingToolbarLayout, something like this:

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

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/recyclerview"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintTop_toBottomOf="@id/appbar"
    app:layout_behavior="@string/appbar_scrolling_view_behavior" />

<com.google.android.material.appbar.AppBarLayout
    android:id="@+id/appbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:fitsSystemWindows="true"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    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="200dp"
        android:fitsSystemWindows="true"
        app:contentScrim="?attr/colorPrimary"
        app:expandedTitleGravity="bottom"
        app:expandedTitleMarginEnd="16dp"
        app:expandedTitleMarginStart="16dp"
        app:layout_scrollFlags="scroll|exitUntilCollapsed"
        app:title="@string/choose_hero">

        <ImageView
            android:id="@+id/toolbar_image"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:adjustViewBounds="true"
            android:contentDescription="@null"
            android:fitsSystemWindows="true"
            android:scaleType="centerCrop" />

        <androidx.appcompat.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" />
    </com.google.android.material.appbar.CollapsingToolbarLayout>
</com.google.android.material.appbar.AppBarLayout>

</androidx.coordinatorlayout.widget.CoordinatorLayout>

I am using this type of layout and my app bar is collapsing/expanding without hiding any recyclerView items.