Develop Reference

Navigation host is not showing in Navigation graph

main activity (called news activity)
<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"
tools:context=".ui.NewsActivity">
<FrameLayout
android:id="#+id/flFragment"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/bottomNavigationView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<fragment
android:id="#+id/newsNavHostFragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost = "true"
app:NavGraph="#navigation/nav_graph"/>
</FrameLayout>
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/bottomNavigationView"
android:layout_width="match_parent"
android:layout_height="56dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
and mine nav_graph.xml code
<?xml version="1.0" encoding="utf-8"?>
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/news_nav_graph">
</navigation>
i have tried to restart and cache android studio but it didnt work. and also updated navigation dependencies to latest version..

Yes I have found one solution in which i just changed
<fragment
android:id="#+id/newsNavHostFragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost = "true"
app:NavGraph="#navigation/nav_graph"/>
to
<androidx.fragment.app.FragmentContainerView
android:id="#+id/newsNavHostFragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:navGraph="#navigation/nav_graph" />
in short just used this instead i have used <androidx.fragment.app.FragmentContainerView>
Thank You!

Fragment view not scrolling fully in ConstraintLayout

I am working with ConstraintLayout which has basically two views inside it: AppBar Layout and the Navhost Fragment but the view inside fragment either overlaps with the app bar layout or doesnot scroll fully to the bottom. Here is what i've done:
<?xml version="1.0" encoding="utf-8"?>
<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="#f0f8fe"
tools:context=".Activities.MainActivity">
<com.google.android.material.appbar.AppBarLayout
android:id="#+id/app_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:orientation="vertical"
>
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="?attr/colorPrimary" />
</com.google.android.material.appbar.AppBarLayout>
<fragment
android:id="#+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:defaultNavHost="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/app_bar"
app:navGraph="#navigation/nav_graph" />
</androidx.constraintlayout.widget.ConstraintLayout>
And the view layout inside fragment:
<androidx.core.widget.NestedScrollView 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"
android:fillViewport="true"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:context=".ScrollingFragment">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="#dimen/text_margin"
android:text="#string/large_text" />
</androidx.core.widget.NestedScrollView>
I tried the solutions here, does not seem to work

Try to change height of <fragment> to 0dp.
<fragment
android:id="#+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="0dp"
app:defaultNavHost="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/app_bar"
app:navGraph="#navigation/nav_graph" />

Bottom of NavHostFragment hidden behind BottomNavigationView

I have layout with a nav bar at the bottom and the main content inside a NavHostFragment. Now the bottom of the NavHostFragment is hidden behind the nav bar. How can I fix this?
This is the main layout of the activity:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_height="match_parent"
android:layout_width="match_parent">
<fragment
android:id="#+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:layout_constraintBottom_toTopOf="#id/nav_view"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="#navigation/mobile_navigation" />
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/nav_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="0dp"
android:layout_marginEnd="0dp"
android:background="?android:attr/windowBackground"
android:layout_alignParentBottom="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="#menu/bottom_nav_menu" />
</androidx.constraintlayout.widget.ConstraintLayout>
And one of the fragments of the nav host:
<?xml version="1.0" encoding="utf-8"?>
<androidx.core.widget.NestedScrollView
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="wrap_content"
android:isScrollContainer="true"
app:layout_constraintTop_toTopOf="parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
</LinearLayout>
</androidx.core.widget.NestedScrollView>

I had the same problem and I found a cure. #ianhanniballake was right, but that is not a final solution. The problem is in value of 'layout_height' of NavHostFragment. You should walk through next 3 steps in activity_main.xml:
Be sure or remove android:paddingTop="?attr/actionBarSize" from root ConstraintLayout
Add app:layout_constraintTop_toBottomOf="#id/nav_host_fragment" to <BottomNavigationView>
Change in <fragment ... NavHostFragment>
android:layout_height="match_parent"
to
android:layout_height="0dp"
android:layout_weight="1"
=======================
A Little investigation:
Let's create a 'Bottom Navigation Activity'-project from scratch.
Step 0.1:
add background to root of activity_main.xml
android:background="#android:color/holo_green_light"
Step 0.2:
change content of fragment_home.xml to this:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/holo_orange_dark">
<TextView
android:id="#+id/left_top"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="L_T"
android:background="#ffcccc"
android:layout_gravity="start|top"
android:textSize="120sp" />
<TextView
android:id="#+id/right_bottom"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="R_B"
android:background="#ccffcc"
android:layout_gravity="end|bottom"
android:textSize="120sp" />
</FrameLayout>
You will see:
Step 1: remove android:paddingTop="?attr/actionBarSize":
Step 2: Add app:layout_constraintTop_toBottomOf="#id/nav_host_fragment" constraint for BottomNavigationView
Step 3 (Final). change height to 0dp and add android:layout_weight="1" for NavHostFragment
PS.Hope this helps for other similar problems

You're missing a app:layout_constraintTop_toBottomOf="#id/nav_host_fragment" on your nav_view - you need both directions to build a constraint chain:
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/nav_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="0dp"
android:layout_marginEnd="0dp"
android:background="?android:attr/windowBackground"
android:layout_alignParentBottom="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#id/nav_host_fragment"
app:menu="#menu/bottom_nav_menu" />
Of course, there's no reason to use ConstraintLayout for this case - if you have solely vertically stacked, non-overlapping views, you should use a LinearLayout.

Add
android:layout_marginBottom="55dp"
in your androidx.navigation.fragment.NavHostFragment

Set android:layout_height="0dp" for NavHostFragment.
When you want to adjust width / height based on constraints so that they take up remaining space in relation to a constraint with other View, set the width / height to 0dp. Only then the Constraints work.

Try the below layout. You can change the appCustomViewPager to anything which is usable for you.
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.impelsys.ebooks.ui.AppCustomViewPager
android:id="#+id/view_pager"
android:layout_width="0dp"
android:layout_height="0dp"
android:background="#color/colorWhite"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
app:layout_constraintBottom_toTopOf="#+id/nav_view"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="1.0" />
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/nav_view"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="0dp"
android:layout_marginStart="0dp"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="#menu/bottom_nav_menu" />
</androidx.constraintlayout.widget.ConstraintLayout>

I used LinearLayout as main layout and added weights to the child layouts
<?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:orientation="vertical"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">
<fragment
android:id="#+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:navGraph="#navigation/mobile_navigation"
android:layout_weight="2"/>
<com.google.android.material.bottomnavigation.BottomNavigationView
app:itemIconTint="#drawable/bottom_navigation_selector"
app:itemTextColor="#drawable/bottom_navigation_selector"
android:id="#+id/nav_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="0"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="#menu/bottom_nav_menu" />
</LinearLayout>

How to set fragment above bottom navigation view with xml?

I am trying to show a fragment host above bottom navigation view. But bottom nav view takes a portion of the fragment host. I tried solutions of other SO answers but it still not solving the problem.
I used both Relative layout with 'layout_above' attribute and constraint layout with realted attributes to keep the fragment above bottom nav view. But the fragment show the text view is still cut off by bottom nav view.
Heres the xml codes I tried:
With relative layout:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingTop="?attr/actionBarSize">
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/nav_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_marginStart="0dp"
android:layout_marginEnd="0dp"
android:background="?android:attr/windowBackground"
app:menu="#menu/bottom_nav_menu" />
<fragment
android:id="#+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="#id/nav_host_fragment"
android:layout_alignParentStart="true"
app:defaultNavHost="true"
app:navGraph="#navigation/mobile_navigation" />
</RelativeLayout>
with constaint layout:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingTop="?attr/actionBarSize">
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/nav_view"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="0dp"
android:layout_marginEnd="0dp"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:menu="#menu/bottom_nav_menu" />
<fragment
android:id="#+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:layout_constraintBottom_toTopOf="#id/nav_view"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="#navigation/mobile_navigation" />
</androidx.constraintlayout.widget.ConstraintLayout>
How do I set the fragment host above bottom navigation view with xml?

Try using linear layout
<?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:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<fragment
android:id="#+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
app:defaultNavHost="true"
app:navGraph="#navigation/mobile_navigation" />
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/nav_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="0dp"
android:layout_marginEnd="0dp"
android:background="?android:attr/windowBackground"
app:menu="#menu/bottom_nav_menu" />
</LinearLayout>

Replace the paddingTop by 0dp value, that solved it for me.
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingTop="0dp"
android:paddingTop="?attr/actionBarSize" <!-- Delete this line -->
android:layout_marginBottom="?attr/actionBarSize" <!-- If you have BottomNavigationView, add this line, so it doesn't overlap your list -->
>

2 Navigationbars (top and bottom) in android

So I need two navigationbars (one at the bottom and one on the top). But as you can already see on the picture above there is no room for the navigation bar on the bottom because of the map (the navigation bar is below the screen). How can I show the bottom navigation bar WITHOUT setting hardcoding width and heights of the map.
This is my xml file:
<?xml version="1.0" encoding="utf-8"?>
<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:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Main3Activity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/nav_info"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="?android:attr/windowBackground"
app:menu="#menu/bottom_nav_menu" />
<fragment
android:id="#+id/map2"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MapsActivity"></fragment>
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/nav_viedw"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="?android:attr/windowBackground"
app:menu="#menu/bottom_nav_menu" />
</LinearLayout>

As you are using ConstraintLayout, there's no need to use LinearLayout as ConstraintLayout is more efficient and is meant to keep the layout hierarchy flat. You can try as shown below:
<?xml version="1.0" encoding="utf-8"?>
<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:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Main3Activity">
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/nav_info"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="?android:attr/windowBackground"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:menu="#menu/bottom_nav_menu" />
<fragment
android:id="#+id/map2"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/nav_viedw"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/nav_info"
tools:context=".MapsActivity" />
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/nav_viedw"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="?android:attr/windowBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="#+id/nav_info"
app:menu="#menu/bottom_nav_menu" />
</androidx.constraintlayout.widget.ConstraintLayout>

Give some margin bottom in fragments in which you want to show your bottom navigation, as now your fragment taking all height of layout below the top navigation.

<?xml version="1.0" encoding="utf-8"?>
<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:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/nav_info"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="?android:attr/windowBackground"
app:menu="#menu/bottom_nav_menu"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
<fragment
android:id="#+id/map2"
android:layout_width="0dp"
android:layout_height="0dp"
tools:context=".MapsActivity"
app:layout_constraintTop_toBottomOf="#+id/nav_info"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintBottom_toTopOf="#+id/nav_viedw"/>
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/nav_viedw"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="?android:attr/windowBackground"
app:menu="#menu/bottom_nav_menu"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintBottom_toBottomOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>