Develop Reference

How to use the whole space when placing ConstraintLayout inside a NestedScrollView?

I'm trying to put a ConstraintLayout inside a NestedScrollView, but there is a line that separates the ConstraintLayout. I can't place anything underneath that invisible line. I have been trying for hours and can't find the issue.
<?xml version="1.0" encoding="utf-8"?>
<layout 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">
<androidx.core.widget.NestedScrollView
android:id="#+id/premium_layout_id"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#BFFFFFFF"
android:focusableInTouchMode="true"
android:tag="layout/fragment_premium"
app:layout_constraintTop_toTopOf="parent">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".PremiumFragment">
<ImageView
android:id="#+id/launcher_id"
android:layout_width="185dp"
android:layout_height="185dp"
android:layout_marginTop="25dp"
android:layout_marginBottom="20dp"
android:contentDescription="TODO"
app:layout_constraintBottom_toTopOf="#+id/premium_text_id"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/launch_premium" />
<TextView
android:id="#+id/premium_text_id"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="220dp"
android:text="#string/launch_to_premium"
android:textSize="24sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView2"
android:layout_width="383dp"
android:layout_height="196dp"
android:layout_marginTop="24dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/premium_text_id" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.core.widget.NestedScrollView>
</layout>

With a little bit of messing around I was able to get what you are looking for. The key is to use android:fillViewport="true" in the NestedScrollView
<?xml version="1.0" encoding="utf-8"?>
<layout 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">
<androidx.core.widget.NestedScrollView
android:id="#+id/premium_layout_id"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#BFFFFFFF"
android:focusableInTouchMode="true"
android:fillViewport="true"
android:tag="layout/fragment_premium">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ImageView
android:id="#+id/launcher_id"
android:layout_width="180dp"
android:layout_height="180dp"
android:layout_marginTop="25dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/launch_premium" />
<TextView
android:id="#+id/premium_text_id"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/launch_to_premium"
android:textSize="24sp"
android:layout_marginTop="20dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/launcher_id" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView2"
android:layout_width="383dp"
android:layout_height="196dp"
android:layout_marginTop="24dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/premium_text_id" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.core.widget.NestedScrollView>
</layout>

You need to add a attribute android:fillViewport="true" in your NestedScrollView
<androidx.core.widget.NestedScrollView
android:id="#+id/premium_layout_id"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#BFFFFFFF"
android:focusableInTouchMode="true"
android:fillViewport="true" <-- add this
android:tag="layout/fragment_premium">
why?
fillViewport allows NestedScrollView to extend its height equals to the full height of the device screen height in the cases when the child of scroll view has less height.
this blog Will explain more about it.

How to add button in the bottom of recyclerview in constraint layout?

I am new to constraint layout and I am trying to add my button below recyclerview, but I am not able to do that in constraint layout.
How I can achieve this functionality in constraint layout.
I am also share image for better understanding.

Try this sample code:
<androidx.constraintlayout.widget.ConstraintLayout 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">
<ListView
android:id="#+id/listView"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/button"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/button"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
The important point is that the ListView's height must be 0 and app:layout_constraintBottom_toTopOf="#+id/button" and app:layout_constraintTop_toTopOf="parent" .

Try something like this:
<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/constraintLayout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ListView
android:id="#+id/listview"
android:layout_width="wrap_content"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/myButton"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/myButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

Is there any way to put recyclerview and linearlayout in swiperefreshlayout?

If I put only RecyclerView into SwipeRefreshLayout I have buttons above RecyclerView. And if I put all into SwipeRefresh I have buttons disappear
<android.support.v4.widget.SwipeRefreshLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/swipe_container"
android:layout_width="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="#+id/students_list"
android:layout_width="match_parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
android:layout_height="0dp"
android:layout_marginBottom="8dp"
app:layout_constraintBottom_toTopOf="#+id/buttonsLayout">
</android.support.v7.widget.RecyclerView>
</android.support.v4.widget.SwipeRefreshLayout>
<LinearLayout
android:id="#+id/buttonsLayout"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="8dp"
app:layout_constraintBottom_toBottomOf="parent"
android:orientation="horizontal">
<android.support.v7.widget.AppCompatButton
android:id="#+id/selectAllButton"
android:text="Выбрать всех"
android:layout_weight="1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</LinearLayout>
Is there any way to fix this?

SwipeRefreshLayout accepts only one child, so maybe you can have a ConstraintLayout inside the SwipeRefreshLayout, and the RecyclerView with the Buttons inside the ConstraintLayout.
PS: I suggest a ConstraintLayout to avoid nested layouts.
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/swipe_container"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior">
<android.support.constraint.ConstraintLayout>
<android.support.v7.widget.RecyclerView
android:id="#+id/students_list"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_marginBottom="8dp"
app:layout_constraintBottom_toTopOf="#+id/selectAllButton"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
<android.support.v7.widget.AppCompatButton
android:id="#+id/selectAllButton"
android:text="Выбрать всех"
android:layout_weight="1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toBottomOf="parent" />
</android.support.constraint.ConstraintLayout>
</android.support.v4.widget.SwipeRefreshLayout>

ConstraintLayout does not get constrained to bottom when lower subviwe gets hidden

I tried to make the title as descriptive as possible.
I have a ConstraintLayout with two LinearLayout children that have ScrollViews inside as there are a lot of stuff inside. Each child has a weight of 1. The layout has constraints to top of toolbar, bottom, left and right to parent and a margin to top. So basically, this layout acts as a bottom sheet that slides up and down.
Both sub-views (LinearLayouts-s) can be "expanded", in which case, the other sub-view changes its visibility to gone.
So what happens is when I expand one layout and hide another, for some reason, the whole layout's alignment stays to top of the parent, preserving the margin, but gets cut to the bottom, leaving an empty space. I want it to move to the bottom of the screen is such case. I have also added app:layout_constraintVertical_bias="1.0", which I thought would take care of it. But it does not work. I will attach pictures.
So what I am trying to achieve is to make the sheet to get aligned bottom all the time. Here is my code:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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:background="?ord_canvas_secondary_color">
<include
android:id="#+id/toolbar"
layout="#layout/toolbar"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<FrameLayout
android:id="#+id/content"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="#id/toolbar">
<include layout="#layout/merge_screen_container" />
</FrameLayout>
<View
android:id="#+id/dim_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:alpha="0.5"
android:background="#color/ord_black"
android:clickable="true"
android:focusable="true"
android:visibility="gone"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/toolbar" />
<FilterSheet
android:id="#+id/subscriptions_filter"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_marginStart="#dimen/dim_8x"
android:layout_marginTop="#dimen/dim_56x"
android:layout_marginEnd="#dimen/dim_8x"
android:layout_marginBottom="#dimen/dim_8x"
android:visibility="invisible"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/toolbar"
app:layout_constraintVertical_bias="1.0" />
</android.support.constraint.ConstraintLayout>

This should work. Please try.
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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:background="?ord_canvas_secondary_color">
<include
android:id="#+id/toolbar"
layout="#layout/toolbar"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<FrameLayout
android:id="#+id/content"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="#id/toolbar">
<include layout="#layout/merge_screen_container" />
</FrameLayout>
<View
android:id="#+id/dim_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:alpha="0.5"
android:background="#color/ord_black"
android:clickable="true"
android:focusable="true"
android:visibility="gone"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/toolbar" />
<android.support.constraint.ConstraintLayout
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/toolbar"
app:layout_constraintVertical_bias="1.0" >
<FilterSheet
android:id="#+id/subscriptions_filter"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="#dimen/dim_8x"
android:layout_marginTop="#dimen/dim_56x"
android:layout_marginEnd="#dimen/dim_8x"
android:layout_marginBottom="#dimen/dim_8x"
android:visibility="invisible"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
/>
</android.support.constraint.ConstraintLayout>
</android.support.constraint.ConstraintLayout>

Try this
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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:background="?ord_canvas_secondary_color">
<include
android:id="#+id/toolbar"
layout="#layout/toolbar"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<FrameLayout
android:id="#+id/content"
android:layout_width="0dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="#id/toolbar">
<include layout="#layout/merge_screen_container" />
</FrameLayout>
<View
android:id="#+id/dim_layout"
android:layout_width="0dp"
android:layout_height="0dp"
android:alpha="0.5"
android:background="#color/ord_black"
android:clickable="true"
android:focusable="true"
android:visibility="gone"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/toolbar" />
<FilterSheet
android:id="#+id/subscriptions_filter"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="#dimen/dim_8x"
android:layout_marginTop="#dimen/dim_56x"
android:layout_marginEnd="#dimen/dim_8x"
android:layout_marginBottom="#dimen/dim_8x"
android:visibility="invisible"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/toolbar" />
</android.support.constraint.ConstraintLayout>

So, the answer from #Arti Patel kinda worked, but the filter view would still go beyond toolbar. I ended up using LinearLayout and FrameLayout.
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="?ord_canvas_secondary_color"
android:orientation="vertical">
<include
android:id="#+id/toolbar"
layout="#layout/toolbar" />
<include layout="#layout/merge_screen_container" />
</LinearLayout>
<View
android:id="#+id/dim_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:alpha="0.5"
android:background="#color/ord_black"
android:clickable="true"
android:focusable="true"
android:visibility="gone" />
<FilterSheet
android:id="#+id/subscriptions_filter"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:layout_marginStart="#dimen/dim_8x"
android:layout_marginTop="#dimen/filter_margin_top"
android:layout_marginEnd="#dimen/dim_8x"
android:layout_marginBottom="#dimen/dim_8x"
android:visibility="invisible" />
</FrameLayout>

Fragment Content Overlaps Toolbar and Bottom Navigation View

I have implemented a bottom navigation view in my android application. With five fragments. However, I have a problem that each time I change the fragment the content of the fragment overlaps the toolbar.
layout for the bottom navigation view
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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=".DashboardActivity">
<include layout="#layout/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content">
</include>
<FrameLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_above="#+id/navigationView"
android:layout_height="match_parent"
/>
<android.support.design.widget.BottomNavigationView
android:id="#+id/navigationView"
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:itemBackground="#android:color/white"
app:itemIconTint="#color/cardview_dark_background"
app:itemTextColor="#android:color/black"
app:menu="#menu/navigation_menu"
/>
</android.support.constraint.ConstraintLayout>
an example of one of the fragments layout
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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/frameLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".AttendanceFragment">
<android.support.constraint.Guideline
android:id="#+id/guideline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.7" />
<android.support.v7.widget.CardView
android:id="#+id/cardView2"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintBottom_toTopOf="#+id/barrier3"
app:layout_constraintEnd_toStartOf="#+id/guideline"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<Spinner
android:id="#+id/spinner_courses"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:paddingBottom="4dp"
android:paddingTop="4dp"
app:layout_constraintEnd_toStartOf="#+id/guideline"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.v7.widget.CardView>
<TextView
android:id="#+id/tv_time"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:gravity="center"
android:textColor="#color/colorPrimaryDark"
android:textSize="12sp"
app:layout_constraintBottom_toTopOf="#+id/barrier3"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="#+id/guideline"
app:layout_constraintTop_toTopOf="parent"
tools:text="Date" />
<android.support.design.widget.FloatingActionButton
android:id="#+id/add_fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="bottom|right"
android:layout_margin="16dp"
android:src="#drawable/ic_add_icon"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintRight_toRightOf="parent"/>
<!--<android.support.design.widget.FloatingActionButton
android:id="#+id/floatingActionButton"
android:layout_width="30dp"
android:layout_height="30dp"
android:layout_marginBottom="4dp"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="4dp"
android:clickable="true"
app:srcCompat="#drawable/ic_more_vert_black_24dp"
app:fabSize="mini"
app:layout_constraintBottom_toBottomOf="#+id/textView3"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/spinner"
app:layout_constraintTop_toTopOf="parent"
android:focusable="true" />-->
<android.support.constraint.Barrier
android:id="#+id/barrier3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:barrierDirection="bottom"
app:constraint_referenced_ids="cardView2,tv_time"
tools:layout_editor_absoluteY="511dp" />
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_marginTop="4dp"
app:cardBackgroundColor="#color/colorMainBackground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/barrier3">
<android.support.v7.widget.RecyclerView
android:id="#+id/rv_register"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v7.widget.RecyclerView>
</android.support.v7.widget.CardView>
</android.support.constraint.ConstraintLayout>
This is what the screen look like with overlapping content

I removed from my ConstraintLayout the default generated marginTop field, and changed my fragment's layout_height to 0dp. Then in all of my Fragments' layout's the outermost layout_height I always set to match parent.
<?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">
<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="0dp"
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" />
</androidx.constraintlayout.widget.ConstraintLayout>

Add margins to container:
<FrameLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_above="#+id/navigationView"
android:layout_height="match_parent"
android:layout_marginBottom="{bottom_navigation_height}"
android:layout_marginTop="{tool_bar_height}"
/>

You should add constraints to your #id/container.
To the top to your toolbar and to the bottom to the BottomNavigationBar. The same should you do to these elements. Toolbar top to parent and toolbar bottom to container. BottomNavigationBar top to container and bottom to parent. Then set the height of the container to 0dp.
<include layout="#layout/toolbar"
android:id="#+id/toolbar"
android:layout_width="0dp"
android:layout_height="?attr/actionBarSize"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"/>
<FrameLayout
android:id="#+id/container"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="#+id/navigationView"
app:layout_constraintTop_toTopOf="#id/toolbar"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"/>
<android.support.design.widget.BottomNavigationView
android:id="#+id/navigationView"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"/>
Didn't test the code but should work.

Its overlapping because You have not giving proper constraint to your controls.
You can try this way.
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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">
<include
android:id="#+id/include"
layout="#layout/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
<FrameLayout
android:id="#+id/container"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/navigationView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/include" />
<android.support.design.widget.BottomNavigationView
android:id="#+id/navigationView"
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:itemBackground="#android:color/white"
app:itemIconTint="#color/cardview_dark_background"
app:itemTextColor="#android:color/black"
app:menu="#menu/navigation_menu"
/>
</android.support.constraint.ConstraintLayout>

In Recent Android Studio Versions (4.0.beta 1), if the hierarchy on the default generated activity_main.xml (omitted attributes) is as following,
<androidx.constraintlayout.widget.ConstraintLayout>
<com.google.android.material.bottomnavigation.BottomNavigationView />
<fragment />
</androidx.constraintlayout.widget.ConstraintLayout>
The fragments seems overlapping the bottom navigation, just rearranging it as shown below,
<androidx.constraintlayout.widget.ConstraintLayout>
<fragment />
<com.google.android.material.bottomnavigation.BottomNavigationView />
</androidx.constraintlayout.widget.ConstraintLayout>
fixed the problem for me without touching any constraints and NOT adding any padding or margins

your fragment container used "match_parent",which take up the position of toolbar and navigationBar,maybe you can choice nested LinearLayout and use height=warp_content, weight=1