Develop Reference

Android GUI looks different when using margin and padding

I'm a beginner on Android, but my question require a little bit knowledge in UI and not in programming.
I have an xml code, i have their some views but for this question only two components are relevant.
The component is a ScrollView "father" that has only one "son" that is a TextView.
When setting padding in ScrollView, if the text inside the TextView is long, first line of TextView is a little bit truncated (although i am using padding). But on the other hand, when using margin_layout text is seen fine. I read a lot on the difference between margin and padding and from what i have understand setting padding inside father should give the same affect as setting margin inside son. I emphasize that i'm using only one son.
Code with margin (where text is fine):
<?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:background="#color/colorPrimary"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="76dp"
android:layout_marginEnd="8dp"
android:fontFamily="#font/chewy"
android:text="#string/title"
android:textSize="36sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<android.support.v7.widget.CardView
android:id="#+id/cardView"
android:layout_width="300dp"
android:layout_height="80dp"
android:layout_marginStart="8dp"
android:layout_marginTop="68dp"
android:layout_marginEnd="8dp"
app:cardCornerRadius="5dp"
app:cardElevation="7dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<TextView
android:id="#+id/question_textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_margin="8dp"
android:text="Hello There this is where we are going to add something..."
android:textSize="18sp" />
</ScrollView>
</android.support.v7.widget.CardView>
<Button
android:id="#+id/true_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="48dp"
android:layout_marginTop="8dp"
android:background="#color/colorAccent"
android:text="#string/true_title"
app:layout_constraintStart_toEndOf="#+id/prev_button"
app:layout_constraintTop_toBottomOf="#+id/cardView" />
<Button
android:id="#+id/false_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:background="#color/colorAccent"
android:text="#string/false_title"
app:layout_constraintEnd_toStartOf="#+id/next_button"
app:layout_constraintStart_toEndOf="#+id/true_button"
app:layout_constraintTop_toBottomOf="#+id/cardView" />
<ImageButton
android:id="#+id/prev_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:background="#color/colorAccent"
android:contentDescription="#string/previous_button"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/cardView"
app:srcCompat="#android:drawable/ic_media_previous" />
<ImageButton
android:id="#+id/next_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:background="#color/colorAccent"
android:contentDescription="#string/next_button"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/cardView"
app:srcCompat="#android:drawable/ic_media_next" />
<TextView
android:id="#+id/counter_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp"
android:fontFamily="#font/chewy"
android:text="#string/counter_questions"
app:layout_constraintBottom_toTopOf="#+id/cardView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView" />
</android.support.constraint.ConstraintLayout>
Code with padding (where first line is truncated)
<?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:background="#color/colorPrimary"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="76dp"
android:layout_marginEnd="8dp"
android:fontFamily="#font/chewy"
android:text="#string/title"
android:textSize="36sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<android.support.v7.widget.CardView
android:id="#+id/cardView"
android:layout_width="300dp"
android:layout_height="80dp"
android:layout_marginStart="8dp"
android:layout_marginTop="68dp"
android:layout_marginEnd="8dp"
app:cardCornerRadius="5dp"
app:cardElevation="7dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="8dp"
>
<TextView
android:id="#+id/question_textview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:text="Hello There this is where we are going to add something..."
android:textSize="18sp" />
</ScrollView>
</android.support.v7.widget.CardView>
<Button
android:id="#+id/true_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="48dp"
android:layout_marginTop="8dp"
android:background="#color/colorAccent"
android:text="#string/true_title"
app:layout_constraintStart_toEndOf="#+id/prev_button"
app:layout_constraintTop_toBottomOf="#+id/cardView" />
<Button
android:id="#+id/false_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:background="#color/colorAccent"
android:text="#string/false_title"
app:layout_constraintEnd_toStartOf="#+id/next_button"
app:layout_constraintStart_toEndOf="#+id/true_button"
app:layout_constraintTop_toBottomOf="#+id/cardView" />
<ImageButton
android:id="#+id/prev_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:background="#color/colorAccent"
android:contentDescription="#string/previous_button"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/cardView"
app:srcCompat="#android:drawable/ic_media_previous" />
<ImageButton
android:id="#+id/next_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:background="#color/colorAccent"
android:contentDescription="#string/next_button"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/cardView"
app:srcCompat="#android:drawable/ic_media_next" />
<TextView
android:id="#+id/counter_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp"
android:fontFamily="#font/chewy"
android:text="#string/counter_questions"
app:layout_constraintBottom_toTopOf="#+id/cardView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView" />
</android.support.constraint.ConstraintLayout>
In addition, putting padding inside CardLayout make thins to be even bad than when adding padding inside the ScrollView
Can someone explain me the reason?

It seems that the difference related to ScrollView odd behavior. I fixed the issue by setting android:fillViewport="true", and removing padding and margin_layout

View Pager not scrolling in a scrollView

I'm having a ViewPager and a RecyclerView in layout file. I want to make the entire layout Scrollable. That is i want the ViewPager to be scrolled up. Hence, i added <ScrollView> as the root layout.
Issue:
The problem i'm facing is that the RecyclerView in scrolling as expected, but the ViewPager area is fixed.
The Below Image depicts the issue mentioned above:
The xml code of my layout file is as shown below:
<ScrollView
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:fillViewport="true"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.constraintlayout.widget.Guideline
android:id="#+id/home_viewpager_guideline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.4" />
<androidx.viewpager.widget.ViewPager
android:id="#+id/home_view_pager"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/home_viewpager_guideline"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<LinearLayout
android:id="#+id/home_viewpager_dots_layout"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:layout_marginBottom="16dp"
android:gravity="center"
android:orientation="horizontal"
app:layout_constraintBottom_toTopOf="#+id/home_viewpager_guideline"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="1.0"></LinearLayout>
<androidx.constraintlayout.widget.ConstraintLayout
android:id="#+id/linearLayout3"
android:layout_width="match_parent"
android:layout_height="0dp"
android:background="#color/latest_news_bg"
app:layout_constraintBottom_toTopOf="#+id/latest_news_guideline"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/home_view_pager">
<View
android:id="#+id/divider2"
android:layout_width="0dp"
android:layout_height="3dp"
android:background="#color/gray"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.16"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="parent"
app:layout_constraintVertical_bias="1.0" />
<TextView
android:id="#+id/latest_news_txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
android:text="Latest News"
android:textColor="#color/dark_gray"
android:textSize="22sp"
app:layout_constraintBottom_toTopOf="#+id/divider2"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
<androidx.constraintlayout.widget.Guideline
android:id="#+id/latest_news_guideline"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.51" />
<TextView
android:id="#+id/home_article_type_txt"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginLeft="16dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="16dp"
android:layout_marginRight="16dp"
android:fontFamily="sans-serif-medium"
android:text="Featured Article"
android:textColor="#color/pf_white"
android:textSize="20sp"
app:layout_constraintBottom_toTopOf="#+id/home_viewpager_dots_layout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.02"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.65" />
<TextView
android:id="#+id/home_article_title_txt"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginLeft="16dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="16dp"
android:layout_marginRight="16dp"
android:layout_marginBottom="8dp"
android:text="What better way to put your health and wellbeing first than"
android:textColor="#color/pf_white"
android:textSize="20sp"
android:textStyle="bold"
app:layout_constraintBottom_toTopOf="#+id/home_viewpager_dots_layout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.05"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/home_article_type_txt"
app:layout_constraintVertical_bias="0.0" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/home_article_list"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/linearLayout3"
app:layout_constraintVertical_bias="1.0" />
</androidx.constraintlayout.widget.ConstraintLayout>
</ScrollView>
What have i tried?
As mentioned in this answer Android ScrollView not Scrolling
, i have tried setting the ScrollView orientation to vertical and fillViewPort property to true, but the problem still persists.
I have also tried using NestedScrollView as the root, but that too didn't work.
If someone can suggest me how to go about with this, it will be really helpful to anyone facing such issue.

NestedScrollView Having Constraint Layout not scrolling

My xml is composed by one constraint layout. Inside this there are 2 buttons and 1 nested scroll view. Inside the ScrollView there are various elements including recycle view. I would like that the recycle view not scroll but scroll only the nested scroll view. I have disabled the scroll of recycle view in this mode
(recyclerView.setNestedScrollingEnabled(false);)
but the problem is that the nested scroll view not scrolling. Can you help me?
I attach the code below.
The code start in this mode :
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<TextView
android:id="#+id/azzera"
android:layout_width="120dp"
android:layout_height="40dp"
android:layout_marginStart="40dp"
android:layout_marginBottom="28dp"
android:background="#drawable/rounded_4lati"
android:backgroundTint="#color/azzurro"
android:elevation="#dimen/dimen8"
android:paddingTop="#dimen/dimen8"
android:text="#string/azzera"
android:textAlignment="center"
android:textColor="#FFFFFF"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<TextView
android:id="#+id/conferma"
android:layout_width="120dp"
android:layout_height="40dp"
android:layout_marginEnd="16dp"
android:layout_marginBottom="28dp"
android:background="#drawable/rounded_4lati"
android:backgroundTint="#color/azzurro"
android:paddingTop="#dimen/dimen8"
android:text="#string/conferma"
android:textAlignment="center"
android:textColor="#FFFFFF"
android:elevation="#dimen/dimen8"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent" />
<android.support.v4.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="match_parent"
android:fillViewport="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
>
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<View
android:id="#+id/view1"
android:layout_width="0dp"
android:layout_height="48dp"
android:background="#color/white"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<View
android:id="#+id/view2"
android:layout_width="0dp"
android:layout_height="48dp"
android:layout_marginTop="16dp"
android:background="#color/white"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/view1" />
<View
android:id="#+id/view3"
android:layout_width="0dp"
android:layout_height="48dp"
android:layout_marginTop="16dp"
android:background="#color/white"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/view2" />
<TextView
android:id="#+id/mostraPreferiti"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="8dp"
android:text="#string/mostraPreferiti"
android:textColor="#color/black"
android:textSize="18sp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/view3" />
<TextView
android:id="#+id/creditiEcm"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="10dp"
android:text="#string/creditiECM"
android:textColor="#color/black"
android:textSize="18sp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/view1" />
<EditText
android:id="#+id/editText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:inputType="number"
android:hint="#string/zero"
android:text="#string/editText"
android:textStyle="bold"
app:layout_constraintStart_toEndOf="#+id/creditiEcm"
app:layout_constraintTop_toTopOf="#+id/view1"
android:autofillHints="" />
<Button
android:id="#+id/buttonMeno"
android:layout_width="36dp"
android:layout_height="36dp"
android:layout_marginTop="6dp"
android:layout_marginEnd="16dp"
android:background="#drawable/ic_remove_circle_azzurro_24dp"
android:gravity="center"
android:textAlignment="gravity"
android:textColor="#color/azzurro"
android:textSize="24sp"
app:layout_constraintEnd_toStartOf="#+id/buttonPiu"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/buttonPiu"
android:layout_width="36dp"
android:layout_height="36dp"
android:layout_marginTop="6dp"
android:layout_marginEnd="32dp"
android:background="#drawable/ic_add_circle_azzurro_24dp"
android:gravity="center"
android:textAlignment="gravity"
android:textColor="#color/azzurro"
android:textSize="24sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/mostraCorsiPassati"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:text="#string/mostraCorsiPassati"
android:textColor="#color/black"
android:textSize="18sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="#+id/view2"
app:layout_constraintTop_toTopOf="#+id/view2" />
<Switch
android:id="#+id/switch_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:layout_marginEnd="32dp"
android:theme="#style/SwitchTheme"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="#+id/view2" />
<Switch
android:id="#+id/switch_button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:layout_marginEnd="32dp"
android:theme="#style/SwitchTheme"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="#+id/view3" />
<android.support.v7.widget.AppCompatTextView
android:id="#+id/professioni"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="90dp"
android:layout_marginEnd="8dp"
android:text="#string/professione2"
android:textColor="#color/black"
android:textSize="18sp"
android:textStyle="bold"
app:fontFamily="#font/sanfrancisco"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/mostraCorsiPassati" />
<SearchView
android:id="#+id/searchBar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="4dp"
android:background="#fff"
android:elevation="2dp"
app:layout_constraintHorizontal_bias="0.557"
app:layout_constraintLeft_toRightOf="parent"
app:layout_constraintRight_toLeftOf="parent"
app:layout_constraintTop_toBottomOf="#+id/professioni"
app:queryHint="Cerca..">
</SearchView>
<android.support.v7.widget.RecyclerView
android:id="#+id/listProfessioni"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/searchBar"
android:orientation="vertical"
>
</android.support.v7.widget.RecyclerView>
<TextView
android:id="#+id/professioniNonDisponibili"
android:layout_width="match_parent"
android:layout_height="60dp"
android:layout_marginStart="8dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="8dp"
android:text="#string/professioniNonDisponibili"
android:textAlignment="center"
android:textColor="#color/gray"
android:textSize="18sp"
app:autoSizeMaxTextSize="#dimen/dimen20"
app:autoSizeMinTextSize="#dimen/dimen12"
app:autoSizeTextType="uniform"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/error" />
<ImageView
android:id="#+id/error"
android:layout_width="#dimen/dimen80"
android:layout_height="#dimen/dimen80"
android:layout_marginStart="8dp"
android:layout_marginTop="32dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp"
android:background="#drawable/ic_error_outline_gray_24dp"
android:contentDescription="#string/TODO"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/searchBar"
app:layout_constraintVertical_bias="0.105" />
<ProgressBar
android:id="#+id/progress"
android:layout_width="60dp"
android:layout_height="60dp"
android:layout_marginStart="8dp"
android:layout_marginTop="24dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp"
android:alpha="1"
android:minWidth="80dp"
android:minHeight="80dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="#+id/searchBar"
app:layout_constraintVertical_bias="0.168" />
</android.support.constraint.ConstraintLayout>
</android.support.v4.widget.NestedScrollView>

As i answered in comments
For Someone other facing same problem. This might help.
For some reasons ScrollView doesn't scroll when having ConstraintLayout inside it.
For Workaround we can use LinearLayout or RelativeLayoutinstead of ConstraintLayout inside ScrollView. OR
As OP does put the ConstraintLayout inside Linear or Relative Layout does the trick.

According to Ali Ahmed's answer, a ScrollView doesn't scroll if you have a ConstraintLayout inside it. Well that's not true. I have been using ConstraintLayout inside ScrollView and everything works perfectly fine. Well the problem with the code that you posted is that you are using 0dpas the layout_height of your RecyclerView. 0dp means match_parent. You should be using wrap_content as your layout_height. So that the RecyclerView expands its height according to the elements in it. Doing so will make your code work fine.

Constraint layout leaving space On top

I have a fragment containing a layout
<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="wrap_content"
android:fitsSystemWindows="true"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:layout_editor_absoluteX="8dp"
tools:layout_editor_absoluteY="8dp"
tools:context="tech.pkg.name.fragments.ReportFragment">
<android.support.constraint.ConstraintLayout
android:id="#+id/constraintLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#color/colorPrimaryDark"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<Spinner
android:id="#+id/typeSlector"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/linearLayout2" />
<android.support.constraint.ConstraintLayout
android:id="#+id/linearLayout2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="32dp"
android:background="#drawable/android_date_bgd"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<TextView
android:id="#+id/fromTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginLeft="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:text="#string/from"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/fromDateTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:drawablePadding="5dp"
android:padding="5dp"
android:text="#string/dd_mm_yy"
android:textStyle="bold"
app:layout_constraintBaseline_toBaselineOf="#+id/fromTextView"
app:layout_constraintEnd_toStartOf="#+id/view9"
app:layout_constraintHorizontal_chainStyle="spread_inside"
app:layout_constraintStart_toEndOf="#+id/fromTextView"
app:layout_constraintTop_toTopOf="#+id/fromTextView" />
<View
android:id="#+id/view9"
android:layout_width="1dp"
android:layout_height="0dp"
android:layout_marginBottom="4dp"
android:layout_marginTop="4dp"
android:background="#android:color/black"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="#+id/toTextView"
app:layout_constraintStart_toEndOf="#+id/fromDateTextView"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0" />
<TextView
android:id="#+id/toTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/to"
android:textStyle="bold"
app:layout_constraintBaseline_toBaselineOf="#+id/fromDateTextView"
app:layout_constraintEnd_toStartOf="#+id/toDateTextView"
app:layout_constraintStart_toEndOf="#+id/view9" />
<TextView
android:id="#+id/toDateTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:drawablePadding="5dp"
android:padding="5dp"
android:text="#string/dd_mm_yy"
android:textStyle="bold"
app:layout_constraintBaseline_toBaselineOf="#+id/toTextView"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/toTextView" />
</android.support.constraint.ConstraintLayout>
</android.support.constraint.ConstraintLayout>
<RadioGroup
android:id="#+id/radioGroup"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:orientation="horizontal"
android:padding="10dp"
android:theme="#style/AppTheme.RadioButton"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView8"
tools:layout_constraintLeft_creator="1"
tools:layout_constraintRight_creator="1">
<RadioButton
android:id="#+id/mobileRadioButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginLeft="20dp"
android:layout_weight="0.20"
android:checked="true"
android:text="Mobile"
android:textSize="18sp" />
<RadioButton
android:id="#+id/DTHradioButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_weight="0.14"
android:text="DTH"
android:textSize="18sp" />
</RadioGroup>
<Button
android:id="#+id/button_view_report"
android:layout_width="0dp"
android:layout_height="40dp"
android:layout_marginBottom="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:background="#drawable/button_bgd"
android:text="#string/submit"
android:textColor="#color/colorAccent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/view5"
app:layout_constraintVertical_bias="0.0" />
<View
android:id="#+id/view5"
android:layout_width="0dp"
android:layout_height="1dp"
android:layout_marginEnd="10dp"
android:layout_marginRight="15dp"
android:background="#color/colorEditTextLine"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/radioGroup" />
<CheckBox
android:id="#+id/downloadCheck"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:theme="#style/AppTheme.Checkbox"
app:layout_constraintHorizontal_bias="0.088"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/constraintLayout" />
<TextView
android:id="#+id/textView8"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:text="#string/download"
app:layout_constraintBaseline_toBaselineOf="#+id/downloadCheck"
app:layout_constraintHorizontal_bias="0.02"
app:layout_constraintLeft_toRightOf="#+id/downloadCheck"
app:layout_constraintRight_toRightOf="parent" />
</android.support.constraint.ConstraintLayout>
it is containing in
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/fragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
But in the layout editor it is showing
How can I remove the spacing above?

The problem is with your Activity where you had inflated the Fragment. Actually, i tried it on My system and I'm Getting Proper result.
Check Your Activity's Layout where the FrameLayout is Used.
2nd Possbility
Check your May be Your Theme is Changing this . Check all the possibilities

Try the following code Replacing the ConstraintLayout after the Spinner
<android.support.constraint.ConstraintLayout
android:id="#+id/linearLayout2"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="#drawable/android_date_bgd"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">

What happened to me was smiliar, a space on top that did not show in the editor.
The problem was not in the main layout file I was focusing on, I was displaying some fragments thru a viewpager and the margins on the editor for the pager were 0 so the editor preview did not showed a space on top. However the fragments that were being created/shown had of course a different layout file and in that layout there was a huge space on top because I erroneously thought centering the layout vertically was a good idea for some reason (mainly because I code at night before bed and sometimes im too tired lol). Since the layout height for the viewpager did not match the dimensions of the fragment I had some weird behaviors trying to position the elements of the main layout file.

I was facing a similar problem. By looking at the code snippet in the question I saw the similarity that we both have android:fitsSystemWindows set to True. By removing this android:fitsSystemWindows attribute, my space at the top was removed.

Android Constraint Layout inside Scrollview inside Constraint Layout

I'm my search the closest question was that: Scrollview inside constraint layout does not scroll to the bottom of the parent constraint
But there is no solution =|.
What I'm trying to do:
I have a constraint layout with 3 "parts": top bar, middle content and bottom button.
I want to put a scrollview only for the middle content. So if you scroll down and up you continuous to see the top bar and the bottom button
But this scroll view is not working, I think is something related with "match_parent" in the scrollview, but I can't put this option because as the scrollview is inside a Constraint Layout the size should be relative and if I put match parent it don't fill all spaces.
I'm using already:
fillViewport="true",
layout_constraintBottom_toBottomOf="parent"
Follow the code, scroll view name: "scrollview2"
<?xml version="1.0" encoding="utf-8"?>
<!--Create by Canato 26/09/2017-->
<com.flipboard.bottomsheet.BottomSheetLayout 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/needs_search_bottomsheet"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout_editor_absoluteY="25dp"
tools:layout_editor_absoluteX="0dp">
<android.support.constraint.Guideline
android:id="#+id/horGuideline10"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.1"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="82dp" />
<android.support.constraint.Guideline
android:id="#+id/horGuideline90"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.9"
tools:layout_editor_absoluteY="536dp"
tools:layout_editor_absoluteX="0dp" />
<include
android:id="#+id/actionbar"
layout="#layout/view_actionbar"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toTopOf="#+id/horGuideline10"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
tools:layout_constraintBottom_creator="1"
tools:layout_constraintLeft_creator="1"
tools:layout_constraintRight_creator="1"
tools:layout_constraintTop_creator="1" />
<Button
android:id="#+id/needs_search_save_btn"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_marginEnd="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:background="#drawable/btn_green_bright_half_round_selector"
android:gravity="center"
android:text="#string/str_continue_save"
android:textAllCaps="false"
android:textColor="#color/WHITE"
android:textSize="#dimen/size_text_button"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="#+id/horGuideline90"
tools:layout_constraintBottom_creator="1"
tools:layout_constraintLeft_creator="1"
tools:layout_constraintRight_creator="1" />
<ScrollView
android:id="#+id/scrollView2"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginBottom="0dp"
android:layout_marginTop="0dp"
android:fillViewport="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="#+id/horGuideline10">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="400dp">
<android.support.constraint.Guideline
android:id="#+id/verGuideline20"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.2"
tools:layout_editor_absoluteX="72dp"
tools:layout_editor_absoluteY="206dp" />
<android.support.constraint.Guideline
android:id="#+id/verGuideline55"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.55"
tools:layout_editor_absoluteX="198dp"
tools:layout_editor_absoluteY="206dp" />
<android.support.constraint.Guideline
android:id="#+id/verGuideline90"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_percent="0.9"
tools:layout_editor_absoluteX="324dp"
tools:layout_editor_absoluteY="206dp" />
<android.support.constraint.Guideline
android:id="#+id/horGuideline10in"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.1"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="233dp" />
<android.support.constraint.Guideline
android:id="#+id/horGuideline20"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.2"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="260dp" />
<android.support.constraint.Guideline
android:id="#+id/horGuideline28"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.28"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="282dp" />
<android.support.constraint.Guideline
android:id="#+id/horGuideline38"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.38"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="309dp" />
<TextView
android:id="#+id/needs_search_title_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="16dp"
android:layout_marginStart="16dp"
android:text="#string/service_request_title_text"
android:textColor="#color/ANDROID_DARK_GRAY"
android:textSize="#dimen/title_text_size"
app:layout_constraintBaseline_toBaselineOf="#+id/needs_search_title_edit"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="#+id/verGuideline20" />
<EditText
android:id="#+id/needs_search_title_edit"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:ems="10"
android:hint="#string/service_request_title_explanation_text"
android:inputType="textPersonName"
android:textColorHint="#color/ANDROID_DARK_GRAY"
app:layout_constraintBottom_toTopOf="#+id/horGuideline10in"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="#+id/verGuideline20"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0" />
<ImageView
android:id="#+id/iconLocation"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginBottom="8dp"
android:layout_marginLeft="16dp"
android:layout_marginStart="16dp"
android:layout_marginTop="8dp"
android:contentDescription="#string/service_request_location_icon_contentDescription"
app:layout_constraintBottom_toTopOf="#+id/horGuideline20"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="#+id/verGuideline20"
app:layout_constraintTop_toTopOf="#+id/horGuideline10in"
app:layout_constraintVertical_bias="0.454"
app:srcCompat="#drawable/ic_location_on_gray_24dp" />
<EditText
android:id="#+id/service_request_address_editText"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="16dp"
android:layout_marginRight="16dp"
android:layout_marginTop="8dp"
android:ems="10"
android:hint="#string/service_request_location_text"
android:inputType="textPersonName"
android:textColorHint="#color/ANDROID_DARK_GRAY"
android:textSize="#dimen/size_text_button"
app:layout_constraintLeft_toRightOf="#+id/iconLocation"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="#+id/horGuideline10in" />
<ImageView
android:id="#+id/iconDecribeText"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginLeft="16dp"
android:layout_marginStart="16dp"
android:contentDescription="#string/service_request_text_contentDescription"
app:layout_constraintBottom_toTopOf="#+id/horGuideline38"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="#+id/verGuideline20"
app:layout_constraintTop_toTopOf="#+id/horGuideline28"
app:srcCompat="#drawable/ic_short_text_gray_24dp" />
<EditText
android:id="#+id/needs_search_description_edit"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="16dp"
android:layout_marginRight="16dp"
android:layout_marginTop="8dp"
android:ems="10"
android:hint="#string/service_request_small_text_explanation"
android:inputType="textMultiLine"
android:textColorHint="#color/ANDROID_DARK_GRAY"
android:textSize="#dimen/size_text_button"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="#+id/verGuideline20"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="#+id/horGuideline28" />
<Button
android:id="#+id/needs_search_address_locate_btn"
android:layout_width="0dp"
android:layout_height="0dp"
android:alpha="0.5"
android:background="#android:drawable/dialog_holo_light_frame"
app:layout_constraintBottom_toTopOf="#+id/horGuideline28"
app:layout_constraintLeft_toLeftOf="#+id/verGuideline20"
app:layout_constraintRight_toLeftOf="#+id/verGuideline55"
app:layout_constraintTop_toTopOf="#+id/horGuideline20"
app:layout_constraintVertical_bias="0.0" />
<Button
android:id="#+id/needs_search_address_home_btn"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:alpha="0.5"
android:background="#android:drawable/dialog_holo_light_frame"
app:layout_constraintBottom_toTopOf="#+id/horGuideline28"
app:layout_constraintLeft_toLeftOf="#+id/verGuideline55"
app:layout_constraintRight_toLeftOf="#+id/verGuideline90"
app:layout_constraintTop_toTopOf="#+id/horGuideline20"
app:layout_constraintVertical_bias="0.0" />
<android.support.v7.widget.RecyclerView
android:id="#+id/needs_search_images_recyclerview"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginBottom="0dp"
android:layout_marginEnd="16dp"
android:layout_marginLeft="16dp"
android:layout_marginRight="16dp"
android:layout_marginStart="16dp"
android:layout_marginTop="24dp"
android:focusable="false"
android:focusableInTouchMode="false"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/needs_search_description_edit"
tools:listitem="#layout/needs_search_big_image_list_item" />
</android.support.constraint.ConstraintLayout>
</ScrollView>
</android.support.constraint.ConstraintLayout>
</com.flipboard.bottomsheet.BottomSheetLayout>

Well, I just found the solution with a friend, first I think about delete this, but since other people maybe have the same problem here is the solution:
I just remove all guidelines and build again, connecting the elements without using so many guidelines.
Was a little bit of lucky, because I did this to fix when change the orientation.

You need to create a chain with the following constraints
in the top bar:
app:layout_constraintBottom_toTopOf="#+id/scrollView2"
app:layout_constraintTop_toTopOf="parent"
in the middle content:
app:layout_constraintBottom_toTopOf="#+id/needs_search_save_btn"
app:layout_constraintTop_toBottomOf="#+id/actionbar"
in the bottom button:
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="#+id/scrollView2"