Develop Reference

Android app:layout_constraintDimensionRatio not working within ScrollView->LinearLayout container

I am trying to create a square LinearLayout container of id imgContainer within a ScrollView element, but I am unable to do so because the app:layout_constraintDimensionRatio doesn't seem to be working. Using the following xml code, the imgContainer renders with a height of 0dp:
<?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">
<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"
app:layout_constraintTop_toTopOf="parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<LinearLayout
android:id="#+id/imgContainer"
android:layout_width="match_parent"
android:layout_weight="1"
android:layout_height="0dp"
android:orientation="vertical"
app:layout_constraintDimensionRatio="1:1"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/trackName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginHorizontal="8dp"
android:layout_weight="1"
android:text="Test Name"
android:textSize="25dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/imgContainer" />
<!-- Other stuff -->
</LinearLayout>
</ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>
However, when I move the imgContainer out of the ScrollView like so, the imgContainer is square-shaped as expected.
<?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">
<LinearLayout
android:id="#+id/imgContainer"
android:layout_width="match_parent"
android:layout_weight="1"
android:layout_height="0dp"
android:orientation="vertical"
app:layout_constraintDimensionRatio="1:1"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ScrollView
...>
<!-- Same as above -->
</ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>
I also tried moving out of the LinearLayout it is nested in while still having it within the ScrollView, but that didn't work either. If anyone knows how to fix this, and why this happens, that would be great. Thanks in advance.

app:layout_constraint.. only work under <androidx.constraintlayout.widget.ConstraintLayout
you can try the following:
<ScrollView
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_height="match_parent">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:id="#+id/imgContainer"
android:layout_width="match_parent"
android:layout_weight="1"
android:layout_height="0dp"
android:orientation="vertical"
app:layout_constraintDimensionRatio="1:1"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/trackName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginHorizontal="8dp"
android:layout_weight="1"
android:text="Test Name"
android:textSize="25dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/imgContainer" />
</androidx.constraintlayout.widget.ConstraintLayout>
</ScrollView>

LinearLayout suitable to another LinearLayout

I have two linear layout inside constrainLayout,
The bottom linear layout includes buttons and its height is wrap_content and must be wrap, because sometimes I keep only 1 button and sometimes 2 buttons.
I would like to set height of the top linearLayout to max but without covering the 2nd layout.
So I decided to set match_parent to the first, but after that it covers the 2nd layout.
I can't use weight/weightsum
<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=".MainActivity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
app:layout_constraintBottom_toTopOf="#+id/linearLayout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</LinearLayout>
<LinearLayout
android:id="#+id/linearLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="16dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
<Button
android:id="#+id/button"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Button1" />
<Button
android:id="#+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Button2"
android:visibility="gone" />
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

<?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"
tools:context=".MainActivity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:weightSum="11"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:layout_weight="9"
app:layout_constraintBottom_toTopOf="#+id/linearLayout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</LinearLayout>
<LinearLayout
android:id="#+id/linearLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:layout_weight="1"
android:padding="16dp"
android:weightSum="2"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
<Button
android:id="#+id/button"
android:layout_width="match_parent"
android:layout_weight="1"
android:layout_height="wrap_content"
android:text="Button1" />
<Button
android:id="#+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="Button2"
" />
</LinearLayout>
try this added weight sum and weight to make layout in prportion

Since you are using ConstraintLayout, you can set the height of the first LinearLayout to 0dp. The ConstraintLayout interprets it as "match constraints".
The next step would be to properly define the constraints of the first LinearLayout (which you did).
You can read more about ConstraintLayout here.
<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=".MainActivity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:orientation="vertical"
app:layout_constraintBottom_toTopOf="#+id/linearLayout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</LinearLayout>
<LinearLayout
android:id="#+id/linearLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="16dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
<Button
android:id="#+id/button"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Button1" />
<Button
android:id="#+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Button2"
android:visibility="gone" />
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

To do this you have to use a combination of linearlayout as parent and attribute layoutWeight ,If you use a constant value for layoutWeight for both top layout and button's container , then this will lead to some problem on different screen height devices , instead this solution make you able to set your buttons height as big as enough by setting its container's height to wrapContent and give all top area for the layout content .
You can also make the top linearLayout scrollable to get the best experience possible :
<?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="match_parent"
android:orientation="vertical">
<LinearLayout
android:id="#+id/this_layout_will_fil_all_space_except_the_bottom_layout_space"
android:layout_width="match_parent"
android:layout_height="0dp"
android:orientation="vertical"
android:background="#000000"
android:layout_weight="1">
</LinearLayout>
<LinearLayout
android:id="#+id/button_layout_at_bottom"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:gravity="center_horizontal"
android:padding="10dp">
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button1"
android:layout_marginEnd="50dp"/>
<Button
android:id="#+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button2"
android:visibility="visible" />
</LinearLayout>
</LinearLayout>
For Buttons , you can set its width to wrapContent and add gravity attribute to its parent as above , in this way even if one buttons was gone , the other will fit perfectly in the center of the container .
Enjoy !

The main advantage of using ConstraintLayout is to avoid using any other nested ViewGroups, The more you add more hierarchy in layout, the less performance you'll have. You can check documentation for more.
So for performance wise it's better to add widgets/views directly within the ConstraintLayout.
So, here I removed the bottom LinearLayout, and kept only the buttons directly within the ConstraintLayout, you can do the same for the top LinearLayout, you can just add any underlying views directly to the ConstraintLayout
<?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"
tools:context=".MainActivity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:orientation="vertical"
app:layout_constraintBottom_toTopOf="#+id/button"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</LinearLayout>
<Button
android:id="#+id/button"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="16dp"
android:text="Button1"
app:layout_constraintBottom_toTopOf="#id/button2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<Button
android:id="#+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginEnd="16dp"
android:layout_marginBottom="16dp"
android:text="Button2"
android:visibility="gone"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

How to place elements one below another in constraint layout whose parent is scroll view

What I am having:
I am having 4 widgets, placed inside a constraint layout, whose parent is a scroll view
What I am trying to do:
I am trying to display widgets one below another
What is happening:
Widgets are placed one above another
MyLayout
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:fillViewport="true">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:id="#+id/edtNameId"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/str_name"
android:inputType="text"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"/>
<EditText
android:id="#+id/edtPwdId"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/str_password"
app:layout_constraintBottom_toBottomOf="#+id/edtNameId"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"/>
<TextView
android:id="#+id/txtChangePwdId"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="#string/str_change_password"
app:layout_constraintBottom_toBottomOf="#+id/edtPwdId"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"/>
<Button
android:id="#+id/btnSubmitId"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/str_submit"
app:layout_constraintBottom_toBottomOf="#+id/txtChangePwdId"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</ScrollView>
Output:

You should use layout_constraintTop_toBottomOf instead of app:layout_constraintBottom_toBottomOf
try this
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:fillViewport="true">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:id="#+id/edtNameId"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/str_name"
android:inputType="text"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"/>
<EditText
android:id="#+id/edtPwdId"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="#string/str_password"
app:layout_constraintTop_toBottomOf="#+id/edtNameId"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"/>
<TextView
android:id="#+id/txtChangePwdId"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="#string/str_change_password"
app:layout_constraintTop_toBottomOf="#+id/edtPwdId"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"/>
<Button
android:id="#+id/btnSubmitId"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/str_submit"
app:layout_constraintTop_toBottomOf="#+id/txtChangePwdId"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</ScrollView>

Fragment view not filling the whole fragment space

I have a Fragment composed of three subfragments :
<?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:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white">
<fragment
android:id="#+id/header"
class="xxx.xxx.xxx.HeaderFragment"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<fragment
android:id="#+id/content"
class="xxx.xxx.xxx.ContentFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/footer"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/header" />
<fragment
android:id="#+id/footer"
class="xxx.xxx.xxx.FooterFragment"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:maxHeight="64dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"/>
</android.support.constraint.ConstraintLayout>
This way, the ContentFragment fills the space between HeaderFragment and FooterFragment, as shown in the picture below :
green = header
blue = content
red = footer
Now I would like to add two views to the ContentFragment layout (one TextView and one ScrollView), so that those views take the whole blue space available.
Here is the layout for ContentFragment :
<?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"
android:background="#color/lightBlue">
<TextView
android:background="#color/white"
android:id="#+id/textView"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
app:layout_constraintEnd_toEndOf="#id/right"
app:layout_constraintStart_toStartOf="#id/left"
app:layout_constraintTop_toTopOf="parent"/>
<ScrollView
android:id="#+id/scrollView"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginTop="16dp"
android:background="#color/white"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="#id/right"
app:layout_constraintStart_toStartOf="#id/left"
app:layout_constraintTop_toBottomOf="#+id/textView">
<TextView
android:id="#+id/veryLongTextView"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</ScrollView>
<android.support.constraint.Guideline
android:id="#+id/left"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.05" />
<android.support.constraint.Guideline
android:id="#+id/right"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.95" />
</android.support.constraint.ConstraintLayout>
This is what I get instead :
Can someone explain why there is some space between the bottom of the scrollview and the bottom of the blue part ? It is not what I have defined in the constraints, which is rendered like this in Android Studio :

I am still unsure why this is happening. My guess is that Android cannot compute the right height for the ContentFragment at runtime, because the problem disappears if I define the fragments height using Guidelines as shown below :
<?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:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white">
<fragment
android:id="#+id/header"
class="xxx.xxx.xxx.HeaderFragment"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintBottom_toTopOf="#+id/topLimit"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<fragment
android:id="#+id/content"
class="xxx.xxx.xxx.ContentFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/bottomLimit"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/topLimit" />
<fragment
android:id="#+id/footer"
class="xxx.xxx.xxx.FooterFragment"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintTop_toBottomOf="#id/bottomLimit"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"/>
<android.support.constraint.Guideline
android:id="#+id/topLimit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.15" />
<android.support.constraint.Guideline
android:id="#+id/bottomLimit"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.85" />
</android.support.constraint.ConstraintLayout>
Which is rendered like this :

Fragment content is hidden behind BottomNavigationView when scrolling

I've researched through this quite heavily and am at a loss on what to do - I have some content in a fragment that is being clipped off by the BottomNavigation bar in the activity and am not sure what to do. I've tried adding app:layout_behavior="#string/appbar_scrolling_view_behavior" to the NestedScrollView but the bottom piece of the content (the names of the locations) is still being cut off - there's probably an easy fix for this but I can't figure it out. The XML for my main activity and the "home" fragment is as follows:
activity_home.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:id="#+id/home_screen"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<include layout="#layout/app_bar" />
<FrameLayout
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"/>
<android.support.design.widget.BottomNavigationView
android:id="#+id/bottom_nav"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="start"
android:background="#color/navbarBackground"
app:menu="#menu/bottom_nav_menu" />
</LinearLayout>
home_fragment.xml
<?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/home_fragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="0dp">
<ImageView
android:id="#+id/tokyo_placeholder"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:adjustViewBounds="true"
android:scaleType="fitStart"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/main_screen_placeholder" />
<ImageView
android:id="#+id/airplane_icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/circle_background"
app:layout_constraintBottom_toBottomOf="#+id/tokyo_placeholder"
app:layout_constraintLeft_toLeftOf="#+id/tokyo_placeholder"
app:layout_constraintRight_toRightOf="#+id/tokyo_placeholder"
app:layout_constraintTop_toTopOf="#+id/tokyo_placeholder"
app:srcCompat="#drawable/icons8_airplane_48"
tools:layout_constraintBottom_creator="1"
tools:layout_constraintLeft_creator="1"
tools:layout_constraintRight_creator="1"
tools:layout_constraintTop_creator="1" />
<android.support.v4.widget.NestedScrollView
android:id="#+id/scroll_view"
android:layout_width="0dp"
android:layout_height="286dp"
android:layout_marginBottom="#dimen/app_bar_height"
android:layout_marginStart="5dp"
android:layout_marginTop="5dp"
android:fillViewport="true"
app:layout_constraintBottom_toTopOf="#id/bottom_nav"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/tokyo_placeholder"
tools:layout_constraintLeft_creator="1"
tools:layout_constraintRight_creator="1">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior">
<TextView
android:id="#+id/destination_headline"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/featured_destinations_headline"
android:textAllCaps="true"
android:textAppearance="#style/TextAppearance.AppCompat.Headline"
android:textSize="14sp"
android:textStyle="bold" />
<android.support.v7.widget.RecyclerView
android:id="#+id/featured_destinations_recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/destination_headline" />
<TextView
android:id="#+id/saved_trips_headline"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/featured_destinations_recycler_view"
android:fontFamily="sans-serif"
android:text="#string/saved_trips"
android:textAllCaps="true"
android:textAppearance="#style/TextAppearance.AppCompat.Headline"
android:textSize="14sp"
android:textStyle="bold" />
<android.support.v7.widget.RecyclerView
android:id="#+id/saved_trips_recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="#id/saved_trips_headline" />
</RelativeLayout>
</android.support.v4.widget.NestedScrollView>
</android.support.constraint.ConstraintLayout>
app_bar.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/app_bar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:elevation="4dp"
android:background="#fff"
android:theme="#style/ThemeOverlay.AppCompat.ActionBar"
android:popupTheme="#style/ThemeOverlay.AppCompat.Light"/>
As an example to show what I mean, here is the content when the navigation bar is moved out of the way and here is the content with the bar in the way. I'm thinking that the problem is some sort of margin/padding issue, but can't quite figure out what to fix.
Edit: I've create a repository with the relevant code (and a workable emulator example) here - please be aware that the code is written in Kotlin, but I don't imagine the issue lies witihn any of the actual code, but more within the layout

I'm not sure what is the expected behavior, I cannot understand that just by reading your question. Having applied this patch, which just includes home_fragment.xml layout changes:
<?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/home_fragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="0dp">
<FrameLayout
android:id="#+id/header_container"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent">
<ImageView
android:id="#+id/tokyo_placeholder"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:adjustViewBounds="true"
android:scaleType="fitStart"
app:srcCompat="#drawable/main_screen_placeholder"
tools:ignore="ContentDescription" />
<ImageView
android:id="#+id/airplane_icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal|center_vertical"
android:background="#drawable/circle_background"
app:srcCompat="#drawable/icons8_airplane_48"
tools:ignore="ContentDescription" />
</FrameLayout>
<android.support.v4.widget.NestedScrollView
android:id="#+id/scroll_view"
android:layout_width="0dp"
android:layout_height="0dp"
android:fillViewport="true"
android:paddingLeft="5dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/header_container">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_behavior="#string/appbar_scrolling_view_behavior">
<TextView
android:id="#+id/destination_headline"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/featured_destinations_headline"
android:textAllCaps="true"
android:textAppearance="#style/TextAppearance.AppCompat.Headline"
android:textSize="14sp"
android:textStyle="bold" />
<android.support.v7.widget.RecyclerView
android:id="#+id/featured_destinations_recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/destination_headline"
app:layout_constraintBottom_toTopOf="#id/saved_trips_headline"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/destination_headline" />
<TextView
android:id="#+id/saved_trips_headline"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fontFamily="sans-serif"
android:text="#string/saved_trips"
android:textAllCaps="true"
android:textAppearance="#style/TextAppearance.AppCompat.Headline"
android:textSize="14sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintBottom_toTopOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#id/featured_destinations_recycler_view" />
<android.support.v7.widget.RecyclerView
android:id="#+id/saved_trips_recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintBottom_toTopOf="#id/app_bar"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#id/saved_trips_headline" />
</android.support.constraint.ConstraintLayout>
</android.support.v4.widget.NestedScrollView>
</android.support.constraint.ConstraintLayout>
Then you'll get this output:

#Tai M.
The problem seems to be the hardcoded height of the NestedScrollView. Since you are already using ConstraintLayout, you can easily lay this view without having to add another Relative layout.
If you want to have the Header images one on top of the other, please wrap those in a FrameLayout. Assign an id to the container and add:
app:layout_constraintTop_toBottomOf="#+id/headerImageContainer"
to the NestedScrollView.
Then you can probably get rid of the RelativeLayout and replace it with another ConstraintLayout to structure the rest of the views using constraints only.
Also, by material design definition, the height of the BottomNavigationView is 56dp which you can assign directly rather than making it wrap content in the
activity_home.xml
<ConstraintLayout ...>
<FrameLayout ...>
<ImageView .../>
<ImageView .../>
</FrameLayout>
<NestenScrollView ... wrap_content>
<ConstraintLayout ...>
<TextView .../>
<RecyclerView .../>
<!-- Assign constraints accordingly -->
<TextView .../>
<RecyclerView .../>
</ConstraintLayout>
</NestenScrollView>
</ConstraintLayout>
Hope this helps.