Develop Reference

Scrolling appbar leaving blank space on top of recyclerview

Hi, I have tried to implement the appbar scrolling behavior and it works fine, however, if I scroll when I'm right on the top it seems like there is extra space for one recyclerview row. How do I get rid of the extra space?
activity_main:
<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:layout_height="match_parent"
tools:context=".MainActivity"
android:fitsSystemWindows="true">
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_scrollFlags="scroll|snap|enterAlways" />
</com.google.android.material.appbar.AppBarLayout>
<include layout="#layout/nav_host" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>
fragment_recyclerview:
<?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:layout_height="match_parent"
tools:context=".fragments.recyclerviewFragment.RecyclerviewFragment"
>
<androidx.recyclerview.widget.RecyclerView
android:paddingTop="?attr/actionBarSize"
android:clipToPadding="false"
android:scrollbars="none"
android:id="#+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
/>
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:layout_gravity="bottom|right"
app:layout_anchorGravity="bottom|end|right"
app:layout_anchor="#id/recyclerView"
android:id="#+id/floatingActionButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="24dp"
android:backgroundTint="#color/green_300_org"
android:contentDescription="#string/add_a_task"
android:src="#drawable/ic_baseline_add_24"
app:tint="#color/black" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>

Instead of adding this attribute to the RecyclerView of fragment_recyclerview.xml:
app:layout_behavior="#string/appbar_scrolling_view_behavior"
add it in your activity_main.xml file, and it will work fine.
It will be like:
<include
layout="#layout/nav_host"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
Then you can remove the top padding from your RecyclerView, and you don't need to use CoordinatorLayout in the fragment_recyclerview.xml file as well.

How to use Coordinatorlayout with Linearlayout?

<?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:layout_height="match_parent"
tools:context=".activities.MainActivity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.google.android.material.appbar.MaterialToolbar
style="#style/Widget.MaterialComponents.Toolbar.Surface"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:elevation="4dp"
app:layout_behavior="com.google.android.material.behavior.HideBottomViewOnScrollBehavior"
app:title="#string/app_name" />
<androidx.fragment.app.FragmentContainerView
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
app:defaultNavHost="true" />
<com.google.android.material.bottomnavigation.BottomNavigationView
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:labelVisibilityMode="unlabeled"
app:layout_behavior="com.google.android.material.behavior.HideBottomViewOnScrollBehavior"
app:menu="#menu/menu_bottom_navigation" />
</LinearLayout>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
This attribute app:layout_behavior="com.google.android.material.behavior.HideBottomViewOnScrollBehavior" does not work inside LinearLayout, I tried to put BottomNavigationView outside LinearLayout, and the attribute above worked but I want to put FragmentContainerView above BottomNavigationView and at the same time make the attribute above work. How can I solve the problem?

Update your code like below:
<?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:layout_height="match_parent"
tools:context=".activities.MainActivity">
<com.google.android.material.appbar.AppBarLayout
android:id="#+id/abl"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<com.google.android.material.appbar.MaterialToolbar
style="#style/Widget.MaterialComponents.Toolbar.Surface"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:elevation="4dp"
app:title="#string/app_name" />
</com.google.android.material.appbar.AppBarLayout>
<androidx.fragment.app.FragmentContainerView
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
app:defaultNavHost="true" />
<com.google.android.material.bottomnavigation.BottomNavigationView
android:layout_gravity="bottom"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:labelVisibilityMode="unlabeled"
app:layout_behavior="#string/hide_bottom_view_on_scroll_behavior"
app:menu="#menu/menu_bottom_navigation" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>

I found a simple trick to solve the problem. Inside FragmentContainerView I'm showing a specific fragment and there is NestedScrollView inside the fragment.
I gave these attributes to the NestedScrollView
android:clipToPadding="false"
android:paddingBottom="Should be the same height of BottomNavigationView"
Now the content inside FragmentContainerView will be top of BottomNavigationView and never will touch BottomNavigationView.
The disadvantages of this way
It will leave extra space in the bottom but mostly
BottomNavigationView will cover it
If you give background color for NestedScrollView, The color will
touch BottomNavigationView
But at least it is working as I want.

A ListView overlaps a SearchView in a CoordinatorLayout

I'm fixing an app after the AndroidX migration, and I had a very odd bug that my ListView was not being loaded on the onCreate/onStart/onResume events:
A ListView is not displaying any data on OnCreate/OnStart after AndroidX migration
By matter of chance, I decided to "simplify" my layout and removed a LinearLayout that contained the ListView. After this change, the data was loaded properly because it seems LinearLayout was somehow blocking the getView event. However, after this change, the SearchView is being overlapped by the ListView, and I don't know how to put them in the right order (first the SearchView followed by the ListView).
This is how it looks now:
This is my code:
other_ruins.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
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="match_parent"
android:orientation="vertical">
<androidx.coordinatorlayout.widget.CoordinatorLayout
android:layout_weight="1"
android:layout_width="match_parent"
android:layout_height="match_parent">
<include layout="#layout/search_container" />
<ListView
android:id="#+id/lstOtherRuins"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
android:nestedScrollingEnabled="true"
android:layout_margin="8dp"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:choiceMode="singleChoice"
android:layout_below="#id/toolbar_container"
android:layout_gravity="left|start" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>
<com.google.android.gms.ads.AdView
android:id="#+id/adView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:adSize="SMART_BANNER"
app:adUnitId="#string/banner_ad_unit_id" />
</LinearLayout>
search_container.xml:
<?xml version="1.0" encoding="UTF-8" ?>
<FrameLayout
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/toolbar_container"
android:theme="#style/AppTheme.AppBarOverlay"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
app:theme="#style/ToolBarStyle"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="#color/colorPrimary" />
<com.miguelcatalan.materialsearchview.MaterialSearchView
android:id="#+id/search_view"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</FrameLayout>
Regarding, the search_container I tested also using the AppBarLayout and crashed the app; therefore, it's not a solution.
Any idea how can I fix it? And why is this happening? If you know how to fix the previous issue and somehow call the getView event on the onCreate/onStart/onResume events is another solution.

You need to replace the FrameLayout in the search_container.xml with AppBarLayout as the AppBarLayout should wrap the Toolbar when you're using the Toolbar within the CoordinatorLayout
<?xml version="1.0" encoding="UTF-8" ?>
<com.google.android.material.appbar.AppBarLayout
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/toolbar_container"
android:theme="#style/AppTheme.AppBarOverlay"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
app:theme="#style/ToolBarStyle"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="#color/colorPrimary" />
<com.miguelcatalan.materialsearchview.MaterialSearchView
android:id="#+id/search_view"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</com.google.android.material.appbar.AppBarLayout>

In my case, I needed to wrap my FrameLayout with a AppBarLayout make it work properly, when I didn´t do it, it duplicates the toolbar creating an strange shadow. This is the final change:
<?xml version="1.0" encoding="UTF-8" ?>
<com.google.android.material.appbar.AppBarLayout
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/toolbar_container"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
app:theme="#style/ToolBarStyle"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="#color/colorPrimary" />
<com.miguelcatalan.materialsearchview.MaterialSearchView
android:id="#+id/search_view"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</FrameLayout>
</com.google.android.material.appbar.AppBarLayout>
Only one of them breaks the app.

Elevation on Material Toolbar doesn't produce a shadow

Just as the title says, i've tried multiple combinations of android:elevation and app:elevation, i have no idea what is it, probably i missed something obvious.
xml:
<?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:layout_height="match_parent"
android:orientation="vertical"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:context="com.example.jabotmobile.MainActivity"
android:background="#color/white">
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#color/dark"
app:elevation="8dp">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="?attr/colorPrimary"/>
</com.google.android.material.appbar.AppBarLayout>
<FrameLayout
android:id="#+id/fragmentContainer1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/red_light"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
android:elevation="0dp"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

You have to add android:clipChildren="false" to the parent view.
<androidx.coordinatorlayout.widget.CoordinatorLayout
android:clipChildren="false">
<com.google.android.material.appbar.AppBarLayout>
<androidx.appcompat.widget.Toolbar
app:elevation="8dp"
/>
</com.google.android.material.appbar.AppBarLayout>
Also by default an alpha channel is applied to the shadow for api28+.
You can change this value adding in your app theme the android:spotShadowAlpha attribute (only for api28+):
<!--Alpha value of the spot shadow projected by elevated views, between 0 and 1.-->
<item name="android:spotShadowAlpha">0.x</item>

Toolbar extends when keyboard opens

I have a toolbar that is beneath the status bar. If I click on a TextInputLayout, the keyboard opens but my toolbar will extend as shown here (if the keyboard is closed, the Toolbar has the usual size):
My xml-files:
The toolbar:
<androidx.appcompat.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/backgroundColor"
android:fitsSystemWindows="true"
android:theme="#style/AppTheme.SubAppBarOverlay"
app:popupTheme="#style/AppTheme.PopupOverlay"
app:title="Title"
android:elevation="4dp" />
Where it is included:
<androidx.constraintlayout.widget.ConstraintLayout 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:layout_height="match_parent"
android:background="?attr/backgroundColor"
android:fitsSystemWindows="false"
tools:context=".EditDayActivity">
<include
android:id="#+id/sub_toolbar"
layout="#layout/sub_toolbar"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<RelativeLayout
android:id="#+id/scrollViewContainer"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/sub_toolbar"
android:fitsSystemWindows="false">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
android:fitsSystemWindows="true">
</ScrollView>
</RelativeLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

Try removing the android:fitsSystemWindows="true" from your toolbar
Edit:
Maybe you should use a coordinatorlayout instead and put your toolbar in there.

I had the same problem and eventually got around it by using CoordinatorLayout as my activity root with app:statusBarColor="#color/some_color" and moving android:fitsSystemWindows="true" there. Probably not the best solution but the only one that worked with my layout.
<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"
android:fitsSystemWindows="true"
tools:context=".MyActivity"
app:statusBarBackground="#color/some_color">
...
</androidx.coordinatorlayout.widget.CoordinatorLayout>

I eventually managed to solve my problem by putting the ScrollView directly into the ConstraintLayout like this (and not using a RelativeLayout):
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="?attr/backgroundColor"
android:fitsSystemWindows="true"
tools:context=".MyActivity">
<include
... />
<ScrollView
... />
</androidx.constraintlayout.widget.ConstraintLayout>