Develop Reference

Floating Action button is not showing in Android Coordinator Layout

I am new to Android and UI development. I have downloaded latest version of Windows Android studio and did some basic native UI, it worked well. Now, I am trying to develop floating action button UI.
I have added CoordinatorLayout inside ConstraintLayout. FAB is added inside CoordinatorLayout. My FAB is not visible in layout preview.
I see androidx.coordinatorlayout.widget.CoordinatorLayout text in that layout with background color. Please let me know how to fix this
implementation 'com.google.android.material:material:1.2.0'
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.coordinatorlayout.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#F44336"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
tools:ignore="MissingConstraints">
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:backgroundTint="#color/colorPrimary"
android:src="#drawable/ic_baseline_add_24"
android:layout_gravity="bottom|end"
/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

add constraintTop for your CoordinatorLayout for filling whole screen
app:layout_constraintTop_toTopOf="parent"
or even this will be better
android:layout_width="match_parent"
android:layout_height="match_parent"
with removing all constraints
for test you may also add fixed size FloatingActionButton. if you want to keep wrap_content for FAB then ensure that ic_baseline_add_24 is valid icon with proper size
<?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"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.coordinatorlayout.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#F44336"
tools:ignore="MissingConstraints">
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:layout_width="80dp"
android:layout_height="80dp"
android:backgroundTint="#color/colorPrimary"
android:src="#drawable/ic_baseline_add_24"
android:layout_gravity="bottom|end"
/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
in above code ConstraintLayout isn't needed and you may remove it if you aren't planning to make some more complicated layout. RecyclerView may be placed inside CoordinatorLayout just before FAB - at first REcyclerView will be drawn, after that FAB on top of recycler

Try
<?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"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.coordinatorlayout.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#F44336"
android:layout_gravity="bottom"
tools:ignore="MissingConstraints">
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:layout_width="104dp"
android:layout_height="107dp"
android:layout_gravity="center"
android:foregroundGravity="center"
android:visibility="visible"
android:src="#drawable/ic_baseline_add_24"
app:backgroundTint="#color/colorPrimary" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>
</LinearLayout>

Don't use a CoordinatorLayout with android:layout_height="wrap_content" to contain just the FAB:
<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:fitsSystemWindows="true">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rvItems"
android:scrollbars="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
app:layout_behavior="com.google.android.material.behavior.HideBottomViewOnScrollBehavior"
android:layout_margin="#dimen/fab_margin"
app:srcCompat="#drawable/ic_add_24px" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>

Pin tablayout in Scrollview with appbarlayout

My android app want to have a page like Facebook page which pin the tablayout on top of the screen when scroll below the tablayout.
I have found a few answers on this topic.
pin TabLayout to top and below the toolbar Scrollview
How to make tablayout fixed below action bar?
However, they don't want my app situation because I want to keep my cardview and tablayout in the scrollview. My xml template is as below. Any insight or solution can share?
<?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"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:liftOnScroll="true">
<com.google.android.material.appbar.CollapsingToolbarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_scrollFlags="scroll|enterAlways|snap">
//toolbar content
</com.google.android.material.appbar.CollapsingToolbarLayout>
</com.google.android.material.appbar.AppBarLayout>
<androidx.core.widget.NestedScrollView
android:id="#+id/scrollview"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="com.google.android.material.appbar.AppBarLayout$ScrollingViewBehavior">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<androidx.cardview.widget.CardView
android:id="#+id/checkinhome"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Content card1"
android:textAppearance="#style/TextAppearance.AppCompat.Display3" />
</androidx.cardview.widget.CardView>
<androidx.cardview.widget.CardView
android:id="#+id/checkinhome"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Content card2"
android:textAppearance="#style/TextAppearance.AppCompat.Display3" />
</androidx.cardview.widget.CardView>
<com.google.android.material.tabs.TabLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
</com.google.android.material.tabs.TabLayout>
<androidx.viewpager2.widget.ViewPager2
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</LinearLayout>
</androidx.core.widget.NestedScrollView>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

I believe you are using unnecessary layouts, try following code for guidance -
MainLayout File
<?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">
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<com.google.android.material.appbar.CollapsingToolbarLayout
android:id="#+id/collapsing_toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:contentScrim="#color/colorPrimaryDark"
app:layout_scrollFlags="scroll|exitUntilCollapsed|snap">
<!-- you can put any content you want to hide after scroll in header-->
<!-- as example in putting this image view-->
<ImageView
android:layout_width="match_parent"
android:layout_height="200dp"
android:padding="20dp"
android:scaleType="fitCenter"
android:src="#drawable/default_img"
app:layout_collapseMode="parallax"
app:layout_collapseParallaxMultiplier="0.25" />
<com.google.android.material.tabs.TabLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_collapseMode="pin"
android:layout_gravity="bottom" />
</com.google.android.material.appbar.CollapsingToolbarLayout>
</com.google.android.material.appbar.AppBarLayout>
<androidx.core.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior">
<!-- put content of scroll view here -->
<include layout="scroll_content_layout" />
</androidx.core.widget.NestedScrollView>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
Above layout file will result in following result-
File scroll_content_layout.xml will have content you want as part of your scroll view.
ScrollContentFile
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<androidx.viewpager2.widget.ViewPager2
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<!-- some other layout as part of scroll view -->
</LinearLayout>
Edit
Content inside CollapsingToolbarLayout will collaps on scroll. Any View you want to KEEP on TOP on a scroll or any other customization you need to use layout_collapseMode flag.
CollapseMode Parallax: The content will scroll but a bit
slower than nested scroll view. You can control scroll speed with
layout_collapseParallaxMultiplier flag.
CollapseMode Pin: The content will stay in the same place while this place is still inside the collapsing toolbar.
Please check Collapse modes of CollapsingToolbarLayout
Happy coding -

Umano SlidingUpPanel not working in CoordinatorLayout

I'm using Umano SlidingUpPanel to set a view like the following:
But no matter what I do, It can't be shown hidden. Instead, it's "peeking":
I need it to hide completely. This is my XML resource
<?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"
xmlns:tools="http://schemas.android.com/tools"
android:layout_height="match_parent"
android:layout_width="match_parent"
xmlns:sothree="http://schemas.android.com/tools"
android:id="#+id/coordinator_layout"
tools:context="com.pocket.poktsales.activities.InventoryActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="#style/AppTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<ProgressBar
android:id="#+id/progressBar"
style="?android:attr/progressBarStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical|center_horizontal"
app:layout_anchorGravity="center_vertical|center_horizontal" />
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="#dimen/fab_margin"
android:src="#drawable/ic_box_add" />
<com.sothree.slidinguppanel.SlidingUpPanelLayout
android:layout_height="wrap_content"
android:layout_width="match_parent"
sothree:umanoDragView="#+id/sliding_up_panel"
android:gravity="bottom"
sothree:overlay="false"
sothree:umanoPanelHeight="0dp"
sothree:umanoParalaxOffset="100dp"
sothree:umanoShadowHeight="4dp">
<include
android:id="#+id/include"
layout="#layout/content_inventory" />
<include android:id="#+id/sliding_up_panel"
layout="#layout/content_product_detail"/>
</com.sothree.slidinguppanel.SlidingUpPanelLayout>
</android.support.design.widget.CoordinatorLayout>
I have tried:
use 0 dp for panel height, no results. Actually it'snot even affected by that attribute no matter what's the value.
Wrap it inside a frame Layout with no result.
Can anyone help me to hide it completely?

In my particular case, I added the panel height programatically:
panel.setPanelHeight(0);
And now it's working!

Overlay on top of toolbar and fab

I want to achieve the following:
Overlay the whole activity with a LinearLayout that is currently not visible and revealed with a CircularReveal animation. It should then look like this. (Also, the Fab should be hidden beneath the semi transparent background of the overlay.)
The screenshot was taken from Android Studio's preview.
But instead it looks like this when testing on my phone.
The toolbar and the fab are above the overlay. I attached my layout below.
I know, I could also solve this with a new activity that is drawn over the previous one with a transparent theme but I would prefer this method as it is easier to work with in the future.
<android.support.design.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="com.jonas.gimmefood.MapsActivity">
<fragment
android:id="#+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/Theme.gimmefood.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="#style/Theme.gimmefood.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="#dimen/fab_margin"
app:fabSize="normal"
android:elevation="2dp"
app:srcCompat="#drawable/ic_my_location_24dp" />
<!-- This is the overlay -->
<LinearLayout
android:id="#+id/overlay"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:visibility="visible">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="#dimen/app_bar_height"
android:background="#color/primary_dark"
android:orientation="vertical"
android:elevation="2dp">
<!-- elevation for the drop shadow -->
<FrameLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:weightSum="1">
<android.support.v7.widget.AppCompatEditText
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="start"
android:layout_marginEnd="52dp"
android:layout_marginStart="4dp"
android:hint="#android:string/search_go" />
<android.support.v7.widget.AppCompatImageButton
android:id="#+id/toolbar_close_icon"
style="#style/Widget.AppCompat.Button.Borderless"
android:layout_width="42dp"
android:layout_height="42dp"
android:layout_gravity="end"
android:layout_marginEnd="4dp"
android:background="?selectableItemBackgroundBorderless"
android:src="#drawable/ic_close_24dp" />
</FrameLayout>
horizontal list view with all the circular buttons
...
</LinearLayout>
<View
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/background_transparent"/>
</LinearLayout>
</android.support.design.widget.CoordinatorLayout>

I solved it by using PopupWindow (reference here)

Android floating action button hidden behind of bottom navigation bar

New to android programming & struggling with right now. I'm using android studio's default "Navigation Drawer Activity". On top of that, I've added a Bottom Bar from https://github.com/roughike/BottomBar. But, after adding that my FAB has hidden behind the Bottom Bar.
Here is the Scrrenshot -
I know it's some kind of style issue. I tried to give bottomMargin for FAB. But, it's not working.
Here is my code -
app_bar_main.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"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context="com.bhramaan.android.bhramaan.MainActivity">
<android.support.design.widget.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/BhramaanTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="#style/BhramaanTheme.PopupOverlay" />
</android.support.design.widget.AppBarLayout>
<include layout="#layout/content_main" />
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="#dimen/fab_margin"
android:src="#android:drawable/ic_dialog_email" />
<com.roughike.bottombar.BottomBar
android:id="#+id/bottomBar"
android:layout_width="match_parent"
android:layout_gravity="bottom|end"
android:layout_height="60dp"
android:layout_alignParentBottom="true"
app:bb_behavior="shy"
android:background="#color/bottomBar"
app:bb_activeTabColor="#color/white"
app:bb_tabXmlResource="#xml/bottombar_tabs" />
</android.support.design.widget.CoordinatorLayout>
Need Some Guidance to solve this.

Add app:elevation="#dimen/text_margin" like this:
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_margin="#dimen/fab_margin"
android:src="#android:drawable/ic_dialog_email"
app:elevation="#dimen/text_margin" /><!--adding this line should resolve your problem-->

Here is a solution that works for our use case. Basically we wanted to hide bottom navigation view and the fab that belongs to it whenever the user scrolls in the screen.
For that purpose we have decided to use the app:layout_behavior="com.google.android.material.behavior.HideBottomViewOnScrollBehavior" that comes out of the box for BottomNavigationView. All that is left is to anchor the fab to the BottomNavigationView and use the same layout_behavior on fab, too.
Here is an example of it:
<?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=".MainActivity">
<include layout="#layout/inc_app_bar"/>
<fragment
app:layout_behavior="#string/appbar_scrolling_view_behavior"
android:id="#+id/main_nav_host_fragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
android:name="androidx.navigation.fragment.NavHostFragment"
app:navGraph="#navigation/bottom_nav_graph"/>
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/main_bottom_nav_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
style="#style/Theme.BottomNavigationView"
app:layout_behavior="com.google.android.material.behavior.HideBottomViewOnScrollBehavior"
app:labelVisibilityMode="labeled"
android:background="?android:attr/windowBackground"
app:menu="#menu/bottom_nav_menu"/>
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="#+id/main_fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_anchor="#id/main_bottom_nav_view"
app:layout_anchorGravity="top|end"
android:layout_marginBottom="#dimen/fab_margin_bottom"
android:layout_marginEnd="#dimen/fab_margin_end"
app:layout_behavior="com.google.android.material.behavior.HideBottomViewOnScrollBehavior"
app:srcCompat="#drawable/ic_add_24px"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
Other than that you can define your own layout_behavior for fab as explained in GitHub: BlogPosts / android-coordinatorlayout-scrolling-hide-fab-behavior.md too.
I hope that it helps :)

In advance I let other know this solution fits to my needs. I don't need fancy animations(which is ok, but not for my project requirements). What I did is to wrap the main content(FrameLayout), the FAB and the BottomNavigationView inside a RelativeLayout. Again, I think this could be done in a better way, so i'm open to suggestions.
<android.support.design.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.support.design.widget.AppBarLayout
android:id="#+id/admin_appbar_layout"
android:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar"
android:layout_width="fill_parent"
android:layout_height="?attr/actionBarSize"
android:layout_alignParentTop="true"
tools:elevation="4dp">
<!-- The toolbar -->
<android.support.v7.widget.Toolbar
android:id="#+id/admin_toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:popupTheme="#style/customActionBar"
app:theme="#style/customActionBar"
android:background="?attr/colorPrimary"
android:minHeight="?attr/actionBarSize">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:gravity="center_horizontal">
<TextView
android:id="#+id/tv_toolbar_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
style="#style/H2_bold"
android:text="#string/activity_admin_name"/>
</LinearLayout>
</android.support.v7.widget.Toolbar>
</android.support.design.widget.AppBarLayout>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="?attr/actionBarSize">
<FrameLayout
android:id="#+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="#+id/bottom_navigation_bar"/>
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab_add_new_item"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:src="#drawable/ic_action_new"
android:layout_alignParentEnd="true"
android:layout_above="#+id/bottom_navigation_bar"
android:layout_margin="#dimen/fab_dimen"
tools:elevation="2dp"/>
<android.support.design.widget.BottomNavigationView
android:id="#+id/bottom_navigation_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
app:itemBackground="#color/black"
app:itemIconTint="#color/white"
app:itemTextColor="#color/white"
app:menu="#menu/admin_bottom_navigation_items"
tools:elevation="2dp"/>
</RelativeLayout>
</android.support.design.widget.CoordinatorLayout>
I know the question may seems old, but hope this helps to someone else.

Its just margin issue. Just try to implement this code in your coordinatorLayout
<FrameLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|end"
android:layout_marginBottom="?attr/actionBarSize">
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="#+id/fab"
style="#style/floating_action_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="#dimen/fab_margin"
android:src="#drawable/ic_add_plus" />
</FrameLayout>
And use this style in your style.xml file.
<style name="floating_action_button">
<item name="android:layout_marginBottom">16dp</item>
</style>
We're just doubling the margin. First BottomNavigationView, and Second the default margin of FAB.

Change your xml as this. Add some more properties to your Floating Action Button.
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentRight="true"
android:layout_gravity="bottom|end"
android:layout_marginBottom="70dp"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_marginTop="10dp"
android:src="#android:drawable/ic_dialog_email" />