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Not able show Top & bottom items in recyclerView

I am using recyclerview in my project but bottom items are not displayed in recyclerview.
I tried ScrollView but my app is crashing it shows java.lang.IllegalStateException: ScrollView can host only one direct child this error.
Here is my code
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyler_transaction"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scrollbars="vertical" />
</LinearLayout></FrameLayout>

<ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<RecyclerView
android:id="#+id/rcview"
android:layout_width="0dp"
android:layout_height="0dp"
android:orientation="horizontal"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
Implement your RecyclerView in this manner. You dont need ScrollView to add recyclerview. Recyclerview can scroll by itself.
It will be good of you can add your whole xml and Adapter code.

I think you use the recyclerview as parent layout that this work is wrong, because recyclerview in android just get a adapter that it, and you most use the container layout like scrollbars for show another layout inside it.

You have added more than one ViewGroup as a child of your ScrollView. ScrollView must contain at most one child in order to properly calculate the height of the view.
Below sample code is wrong:
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
....
....
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
....
....
</LinearLayout>
</ScrollView>
In order to solve the problem, you can use the below sample code:
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<!-- here add your views -->
....
....
</LinearLayout>
</ScrollView>

RecyclerView content goes behind and not over TextView above

Consider this video from material design on drag & dropping items:
Material design reordering list
In the video you see a RecyclerView and above it a TextView with the text "Playlist". When the row is dragged up you see it going over the Playlist.
In my code the row goes behind the Textview. I've put RecyclerView's layout_height to match_parent. And I used a FrameLayout and placed the TextView below the RecyclerView. Why isn't it going over it?
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/layoutRoot"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="#+id/txtTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="#dimen/general_margin"
android:text="#string/activity_bible_order_explanation"
android:layout_gravity="start|top" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/transparent"
android:layout_marginTop="96dp"
android:orientation="vertical"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />
</FrameLayout>

Use Constraint layout as a parent layout and add textview at the top by giving top constraints to the textview. then add
recyclerview's top constraint to the the bottom of textview and recyclerview bottom constraint to the bottom of parent then set height 0 it will work
<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/layoutRoot"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="#+id/txtTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintTop_toTopOf="parent"
android:padding="#dimen/general_margin"
android:text="#string/activity_bible_order_explanation"
/>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintTop_toBottomOf="#id/txtTitle"
android:background="#android:color/transparent"
android:layout_marginTop="96dp"
android:orientation="vertical"
app:layout_constraintBottom_toBottomOf="parent"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />
</androidx.constraintlayout.widget.ConstraintLayout>

Have you tried elevation? the problem might be that in the z axis the TextView is higher than the RecyclerView. try adding android:elevation="10dp" or higher... like this:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/layoutRoot"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="#+id/txtTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="#dimen/general_margin"
android:text="#string/activity_bible_order_explanation"
android:layout_gravity="start|top" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:elevation="10dp" (if it doesn't work try maybe higher elevation, 20dp etc.)
android:background="#android:color/transparent"
android:layout_marginTop="96dp"
android:orientation="vertical"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />
</FrameLayout>
Hope it works for you (: let me know!

What is the parent layout of this?
Because you set match_parent in recyclerview and list have many content that's why this issue facing.
Please give fix height or use relative layout and apply position above of text view in recyclerview

Problem with your layout code:
You're using a FrameLayout
Inside FrameLayout, you're also using top margin on your RecyclerView
android:layout_marginTop="96dp" <-- This causing the issue.
Solution:
You should LinearLayout instead of FrameLayout. And, also set LinearLayout's orientation as vertical.
android:orientation="vertical"
Also remove this line from your RecyclerView:-
android:layout_marginTop="96dp"
Solution Code:
<?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/layoutRoot"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="#+id/txtTitle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="16dp"
android:text="Hello World"/>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/transparent"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />
</LinearLayout>

The issue is not that the dragged view is going behind the TextView but, rather, the dragged view is not being drawn outside the bounds of the RecyclerView. The effect is the same.
To allow the RecyclerView to draw outside of itself, set the following for the parent of the RecyclerView:
android:clipChildren="false"
For the RecyclerView set
android:clipToPadding="false"
That should solve the problem.

The RecyclerView is above the text view in your FrameLayout. Currently, it appears that the underlying TextView is above the RecyclerView as you have given the background for the RecyclerView as:
android:background="#android:color/transparent"
To make this work as normal, either remove this line or change the background of RecyclerView to any value other than transparent.

There is 1 more issue. You need to place the recycler view first. Try this:
<?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/layoutRoot"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/transparent"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />
<TextView
android:id="#+id/txtTitle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="16dp"
android:text="Hello World"/>
</LinearLayout>

How to fix a view inside ConstraintLayout while scrolling?

I have a layout which is scrollable. I need to a place a ImageView to the bottom right of the parent and the ImageView should be fixed to that position even while scrolling. Follow is the code I wrote.
<ScrollView 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:orientation="vertical">
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/random_text"
android:textSize="20dp"
app:layout_constraintRight_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="#+id/back_to_top"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/back_to_top"
android:visibility="visible"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintRight_toRightOf="parent" />
</android.support.constraint.ConstraintLayout>
But the ImageView is scrollable along with the content and not fixed. How to achieve this in ConstraintLayout? One solution will be to put ImageView outside the ConstraintLayout, but is there any where to achieve it while placing it inside ConstraintLayout.
Note : This is a very simple layout which I made up for posting the question. The real layout is more complex but has the same problem.

Android - how to make a scrollable constraintlayout?

I want to make a layout that lets me scroll down using constraint layout, but I don't know how to go about it. Should the ScrollView be the parent of the ConstraintLayout like this?
<?xml version="1.0" encoding="utf-8"?>
<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:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true">
<android.support.constraint.ConstraintLayout
android:id="#+id/Constraint"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
Or the other way around? Maybe someone can point me to a good tutorial on this or give an example, I can't seem to find one.
Also, I don't know if this is a bug or some configuration that I don't have set up but I've seen images like this one :
where there are some components outside the blueprint "blue rectangle" yet they are visible, while on my side if I place a component on the "white space" I can't see it or move it anywhere, and it appears on the component tree.
UPDATE :
I found a way to make the constraint layout scrollable in the design tool, using a horizontal guideline to push down the constraint layout border and extend it beyond the device, after that, you can use the guideline as the new bottom of the constraint layout to anchor the components.

It seems that it is working, I don't know what dependency you were working with but in this one
compile 'com.android.support.constraint:constraint-layout:1.0.2'
Is working, this is what I did
<?xml version="1.0" encoding="utf-8"?>
<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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.design.widget.TextInputLayout
android:id="#+id/til_input"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:hint="Escriba el contenido del archivo"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toLeftOf="#+id/btn_save"
app:layout_constraintTop_toTopOf="#id/btn_save"
app:layout_constraintVertical_chainStyle="spread">
<EditText
android:layout_width="match_parent"
android:layout_height="match_parent" />
</android.support.design.widget.TextInputLayout>
<Button
android:id="#+id/btn_save"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="onClickButtonSave"
android:text="Guardar"
app:layout_constraintLeft_toRightOf="#+id/til_input"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/txt_content"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="0dp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#id/til_input"
app:layout_constraintVertical_chainStyle="spread"
app:layout_constraintVertical_weight="1" />
<Button
android:id="#+id/btn_delete"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:onClick="onClickButtonDelete"
android:text="Eliminar"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#id/txt_content"
app:layout_constraintVertical_chainStyle="spread" />
</android.support.constraint.ConstraintLayout>
</ScrollView>
Scroll Top
Scroll Bottom

There is a type of constraint which breaks the scroll function:
Just make sure you are not using this constraint on any view when wanting your ConstraintLayout to be scrollable with ScrollView :
app:layout_constraintBottom_toBottomOf=“parent”
If you remove these your scroll should work.
Explanation:
Setting the height of the child to match that of a ScrollView parent is contradictory to what the component is meant to do. What we want most of the time is for some dynamic sized content to be scrollable when it is larger than a screen/frame; matching the height with the parent ScrollView would force all the content to be displayed into a fixed frame (the height of the parent) hence invalidating any scrolling functionality.
This also happens when regular direct child components are set to layout_height="match_parent".
If you want the child of the ScrollView to match the height of the parent when there is not enough content, simply set android:fillViewport to true for the ScrollView.

Use NestedScrollView with viewport true is working good for me
<android.support.v4.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="700dp">
</android.support.constraint.ConstraintLayout>
</android.support.v4.widget.NestedScrollView>
for android x use this
<androidx.core.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
.....other views....
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.core.widget.NestedScrollView>

To summarize, you basically wrap your android.support.constraint.ConstraintLayout view in a ScrollView within the text of the *.xml file associated with your layout.
Example activity_sign_in.xml
<?xml version="1.0" encoding="utf-8"?>
<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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".SignInActivity"> <!-- usually the name of the Java file associated with this activity -->
<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="#drawable/gradient"
tools:context="app.android.SignInActivity">
<!-- all the layout details of your page -->
</android.support.constraint.ConstraintLayout>
</ScrollView>
Note 1: The scroll bars only appear if a wrap is needed in any way, including the keyboard popping up.
Note 2: It also wouldn't be a bad idea to make sure your ConstraintLayout is big enough to the reach the bottom and sides of any given screen, especially if you have a background, as this will ensure that there isn't odd whitespace. You can do this with spaces if nothing else.

Just use constraint layout inside NestedScrollView or ScrollView.
<android.support.v4.widget.NestedScrollView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white">
</android.support.constraint.ConstraintLayout>
</android.support.v4.widget.NestedScrollView>
thats it. enjoy your coding.

A lot of answers here, nothing really simple. It's important that the ScrollView's layout_height is set to match_parent while the layout_height of the ContraintLayout is wrap_content
<ScrollView
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
...

Please use below solution it has taken my lots of time to fix.
Enjoy your time :)
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white"
>
<ScrollView
android:id="#+id/mainScroll"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white"
android:fillViewport="true"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
android:layout_alignParentStart="true">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="bottom"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_alignParentBottom="true"
android:layout_alignParentEnd="true"
>
</android.support.constraint.ConstraintLayout>
</RelativeLayout>
</ScrollView>
</RelativeLayout>
Use Exactly like this u will definitely find your solution...

TO make a scrollable layout, the layout is correct. It will not be scrollable until there is reason to scroll(just like in any other layout). So add enough content and it will be scrollable, just like with any layout(Linear, Relative, etc). However, you cannot scroll properly in Blueprint or design-mode when designing with ConstraintLayout and ScrollView.
Meaning:
You can make a scrollable ConstraintLayout, but it will not scroll properly in the editor due to a bug/scenario that wasn't considered. But even though scrolling doesn't work in the editor, it works on devices. (I have made several scrolling COnstraintLayouts, so I have tested it)
Note
Regarding your code. The ScrollView is missing a closing tag, I don't know if it is the case in the file or if it is a copy-paste miss, but you may want to look at it.

For completing the previous answers I am adding the following example, which also takes into account the use of the AppBar. With this code, the Android Studio design editor seems to work fine with the ConstraintLayout.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
android:background="#drawable/bg"
android:orientation="vertical">
<android.support.design.widget.AppBarLayout
android:id="#+id/app_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="#style/AppTheme.ActionBar.AppOverlayTheme">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:popupTheme="#style/AppTheme.PopupOverlay"/>
</android.support.design.widget.AppBarLayout>
<ScrollView
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:id="#+id/image_id"
android:layout_width="match_parent"
android:layout_height="#dimen/app_bar_height"
android:fitsSystemWindows="true"
android:scaleType="centerCrop"
android:src="#drawable/intro"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="parent" />
<TextView
android:id="#+id/desc_id"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="#dimen/text_margin"
android:text="#string/intro_desc"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/image_id" />
<Button
android:id="#+id/button_scan"
style="?android:textAppearanceSmall"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:backgroundTint="#color/colorAccent"
android:padding="8dp"
android:text="#string/intro_button_scan"
android:textStyle="bold"
app:layout_constraintTop_toBottomOf="#+id/desc_id" />
<Button
android:id="#+id/button_return"
style="?android:textAppearanceSmall"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginTop="8dp"
android:backgroundTint="#color/colorAccent"
android:padding="8dp"
android:text="#string/intro_button_return"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="#+id/button_recycle" />
<Button
android:id="#+id/button_recycle"
style="?android:textAppearanceSmall"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:backgroundTint="#color/colorAccent"
android:padding="8dp"
android:text="#string/intro_button_recycle"
android:textStyle="bold"
app:layout_constraintTop_toBottomOf="#+id/button_scan" />
</android.support.constraint.ConstraintLayout>
</ScrollView>
</LinearLayout>

you need surrounded my constraint-layout with a ScrollView tag and gave it the property android:isScrollContainer="true".

Take out bottom button from the nestedscrollview and take linearlayout as parent. Add bottom and nestedscrollview as thier children. It will work absolutely fine. In manifest for the activity use this - this will raise the button when the keyboard is opened
android:windowSoftInputMode="adjustResize|stateVisible"
<?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:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<androidx.core.widget.NestedScrollView xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:fillViewport="true">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<com.google.android.material.textfield.TextInputLayout
android:id="#+id/input_city_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="20dp"
android:layout_marginTop="32dp"
android:layout_marginEnd="20dp"
android:hint="#string/city_name"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent">
<com.google.android.material.textfield.TextInputEditText
android:id="#+id/city_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:digits="abcdefghijklmnopqrstuvwxyz ABCDEFGHIJKLMNOPQRSTUVWXYZ"
android:lines="1"
android:maxLength="100"
android:textSize="16sp" />
</com.google.android.material.textfield.TextInputLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.core.widget.NestedScrollView>
<Button
android:id="#+id/submit"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#color/colorPrimary"
android:onClick="onSubmit"
android:padding="12dp"
android:text="#string/string_continue"
android:textColor="#FFFFFF"
app:layout_constraintBottom_toBottomOf="parent" />
</LinearLayout>

There is a bug in version 2.2 that makes it impossible to scroll the ConstraintLayout. I guess it still exists. You can use LinearLayout or RelativeLayout alternatively.
Also, check out: Is it possible to put a constraint layout inside a ScrollView.

Constraintlayout is the Default for a new app. I am "learning to Android" now and had a very hard time figuring out how to handle the default "sample" code to scroll when a keyboard is up. I have seen many apps where I have to close the keyboard to click "submit" button and sometimes it does not goes away. Using this [ScrollView / ContraintLayout / Fields] hierarchy it is working just fine now. This way we can have the benefits and ease of use from ConstraintLayout in a scrollable view.

You can use HorizontalScrollView and it'll work as well!

This is how I resolved it:
If you are using Nested ScrollView i.e. ScrollView within a ConstraintLayout then use the following configuration for the ScrollView instead of "WRAP_CONTENT" or "MATCH_PARENT":
<ScrollView
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintBottom_toTopOf="#+id/someOtherWidget"
app:layout_constraintTop_toTopOf="parent">

in scrollview make height and width 0
add Top_toBottomOfand Bottom_toTopOf constraints
that's it.

For me, none of the suggestions about removing bottom constraints nor setting scroll container to true seemed to work. What worked: expand the height of individual/nested views in my layout so they "spanned" beyond the parent by using the "Expand Vertically" option of the Constraint Layout Editor as shown below.
For any approach, it is important that the dotted preview lines extend vertically beyond the parent's top or bottom dimensions

Scrollview inside constraint layout does not scroll to the bottom of the parent constraint

I have a form which has around 12/13 fields. I used a Scrollview inside a constraint layout. Below is the hierarchy of the XML layout. The problem is, it doesn't scroll to the bottom instead scrolls only to the first initial 10 views. The last 3 fields gets hidden as the view does not scroll any further.
PARENT 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:id="#+id/activity_register"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:focusableInTouchMode="true"
android:orientation="vertical">
<!-- Textview and a button -->
<ScrollView
android:id="#+id/scrollView"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginBottom="10dp"
android:layout_marginTop="10dp"
android:orientation="vertical"
android:overScrollMode="never"
android:scrollbars="none"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/view"
tools:layout_constraintBottom_creator="1"
tools:layout_constraintLeft_creator="1"
tools:layout_constraintRight_creator="1"
tools:layout_constraintTop_creator="1"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="0dp">
<android.support.constraint.ConstraintLayout
android:id="#+id/constraintLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<!-- Child Views (12/13 views of the fields)-->
</android.support.constraint.ConstraintLayout>
</ScrollView>
</android.support.constraint.ConstraintLayout>

This layout works in my app.
The trick is to set these two attributes in ScrollView:
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
The simplified layout from my app:
<?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:theme="#style/ThemeOverlay.AppCompat.Light">
<RelativeLayout
android:id="#+id/linear"
android:layout_width="0dp"
android:layout_height="56dp"
android:background="#color/title"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ScrollView
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#id/linear">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="#+id/titleView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="8dp"
android:layout_marginStart="8dp"
android:text="#string/title"
android:textSize="14sp"
app:layout_constraintBaseline_toBaselineOf="#+id/title"
app:layout_constraintLeft_toLeftOf="parent" />
<EditText
android:id="#+id/title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:hint="toilet title"
android:inputType="text"
android:textColor="#android:color/holo_red_dark"
android:textSize="12sp"
app:layout_constraintLeft_toLeftOf="#+id/open_hour"
app:layout_constraintLeft_toRightOf="#+id/titleView"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
...
Other Views in ScrollView
...
</android.support.constraint.ConstraintLayout>
</ScrollView>
</android.support.constraint.ConstraintLayout>

In my case NestedScrollView worked instead of ScrollView. Following is the snippet of my working 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="match_parent">
<!-- Some Views Here -->
<android.support.v4.widget.NestedScrollView
android:layout_width="0dp"
android:layout_height="0dp"
android:fillViewport="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#+id/view">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<!-- Some Views That can be Scrolled Here -->
</android.support.constraint.ConstraintLayout>
</android.support.v4.widget.NestedScrollView>
</android.support.constraint.ConstraintLayout>

You have two solutions for this problem (the same solution but in two ways to do it):
If you put the Design mode in Android Studio, select your ScrollView and open attributes tab and in the layout_height, select "match_constraint".
If you use the Text mode in Android Studio, use this:
<ScrollView
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="#id/tb_details">
See that the ScrollView height is set to 0dp. Both of this ways resolve the same problem but these are the different ways to do it.
The ScrollView is not the root view, I have a Constraint layout wrapping the ScrollView as you.

Two Steps
Keep layout height for scroll view zero
android:layout_height="0dp"
Again for scroll view
android:fillViewport="true"

Try adding bottom constraint to scrollview (eg: app:layout_constraintBottom_toBottomOf="parent")
and change android:layout_height="wrap_content" to android:layout_height="0dp"

In my case NestedScrollView worked instead of ScrollView.
Following is the snippet of my working layout:
Please make sure that you haven't make any childview height to match parent(0 dp) inside constrianlayout also for scroll view android:fillViewport="true;
Ask me if any doubt Occur.
<android.support.v4.widget.NestedScrollView
android:id="#+id/scroll_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="#dimen/_90sdp"
android:fillViewport="true">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:id="#+id/cvLayout"
android:animateLayoutChanges="true">

Just Put android:fillViewport="true" in Parent Layout

In my case, I had a tall TextView (height set to wrap_content) inside a ScrollView (height set to 0dp and being constraint on the top and bottom). No suggestions worked, but I solved the problem by wrapping the TextView inside a FrameLayout (height set to wrap_content).

Never keep 0dp height of childs of ConstraintLayout if it is inside SV/NestedSV
wrap_content works because in this case ScrollView knows its childens height.

For me, I needed to add a LinearLayout inside my ScrollView in order to constrain it
<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="wrap_content"
app:layout_constraintTop_toTopOf="parent"
tools:layout_editor_absoluteX="1dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<View....</View>
</LinearLayout>
</ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>

I have resolve this issue. Inside ScrollView you can not use constraint Layout.
for using constrain inside scroll u have to use Relative layout is parent of constraint Layout..
so ur sequence should be:
ScrollView ---> Relative Layout ---> Constraint Layout

If you came here after searching "Soft Keyboard Hides the View elements"!
Then you just have to add a scrollView and the same layout element again.
Before
<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">
<ImageView
android:id="#+id/imageView3"
android:layout_width="246dp"
android:layout_height="168dp"
android:layout_marginTop="20dp"
android:src="#drawable/img"/>
<Button
android:id="#+id/btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</androidx.constraintlayout.widget.ConstraintLayout>
After
<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="0dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
android:fillViewport="true">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="#+id/imageView3"
android:layout_width="246dp"
android:layout_height="168dp"
android:layout_marginTop="20dp"
android:src="#drawable/img"/>
<Button
android:id="#+id/btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</ScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>

For the horizontal scroll view case (parent is ConstraintLayout, immediate child is LinearLayout), I found that setting the four constraints, layout_width=0dp, and fillViewport=true was not enough. It still didn't scroll.
What did work in my case was to set the four constraints and change the element from ScrollView to HorizontalScrollView. In that case layout_width can be set to "wrap_content" and fillViewport can be omitted.
Additionally, I added a padding at the end of the immediate child of the HorizontalScrollView, to make the scrolling experience and the look better.

I faced another issue where i had nestedscrollview which has constrainlayout which has linearlayout. This linearlayout has child get added programatically. So scroll was not working. Solved by replacing CL with LL with vertical orientation
<androidx.core.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintTop_toBottomOf="#+id/separatr"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
android:fillViewport="true"
android:fitsSystemWindows="true"
>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
android:orientation="vertical"
tools:background="#color/yellow_highlight"
android:paddingBottom="#dimen/box96">
<TextView
android:id="#+id/qansTv"
style="#style/BodyText"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="#dimen/box200"
android:layout_marginTop="#dimen/box32"
android:layout_marginEnd="#dimen/box200"
android:text="Lorem ipsum dofdfd fsd fdfsd sdf sdfsd fsdfsd fd sdfd fsdfsdf sdfsd df sdfd fsdfsd fsdf sdfsd dflors fdfdf."
android:textColor="#color/white"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<LinearLayout
android:id="#+id/ansImageContainerLL"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:background="#color/red"
android:layout_marginEnd="#dimen/box64"
android:orientation="vertical"
android:layout_marginStart="#dimen/box64"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/qansTv" />
</LinearLayout>
</androidx.core.widget.NestedScrollView>

in my case I had to use 2 recyclerviews and since it didn't want to scroll all the way I found a way to set to which length of the scrollview to scroll, the length is set by changing the width of the TextView.
<?xml version="1.0" encoding="utf-8"?>
<HorizontalScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.ProjectsFragment"
android:background="#color/blue">
<FrameLayout
android:layout_width="wrap_content"
android:layout_height="match_parent">
<TextView
android:id="#+id/scrollViewLength"
android:layout_width="2000dp"
android:layout_height="match_parent"
android:text="Change the width above"
android:visibility="invisible"/>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:tag="exampletag"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView1"
android:tag="exampletag"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_marginTop="28dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
/>
</FrameLayout>
</HorizontalScrollView>

I know I'm late little bit ,I was facing the same issue what I did wrapped my RecyclerView Inside Linear or Relative layout and it worked like a charm,