Develop Reference

How to add recylerview in 1/3rd part of activity

I have on activity in which i need to add one horizontal list for showing the formats of image which should be appear in the lower part of the activity. Here is my xml file.
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white"
android:fitsSystemWindows="true"
tools:context=".view.quickaction.QuickActionVideoActivity">
<RelativeLayout
android:id="#+id/quick_action_video_header_contatiner"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:orientation="vertical"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<TextView
android:id="#+id/quick_action_video_close"
android:layout_width="match_parent"
android:layout_height="25dp"
android:layout_marginTop="20dp"
android:text="#string/button_cancel"
android:textColor="#color/express_purple"
android:textSize="18dp" />
<TextView
android:id="#+id/quick_action_video_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/quick_action_video_close"
android:layout_marginTop="30dp"
android:fontFamily="#font/adobe_clean_bold"
android:text="#string/quick_action_resize_video_header"
android:textColor="#color/black_alpha_85"
android:textSize="32dp" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#id/quick_action_video_title"
android:text="#string/powered_by_magicX"
android:textColor="#color/black_alpha_85"
android:textSize="14dp" />
</RelativeLayout>
<androidx.constraintlayout.widget.ConstraintLayout
android:id="#+id/zoom_surface"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_marginStart="15dp"
android:layout_marginTop="30dp"
android:layout_marginEnd="15dp"
android:background="#drawable/rounded_rectangle_rect"
android:visibility="visible"
app:layout_constraintDimensionRatio="H,5:4"
app:layout_constraintEnd_toStartOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/quick_action_video_header_contatiner">
<com.otaliastudios.zoom.ZoomSurfaceView
android:id="#+id/surface_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="25dp"
android:layout_marginBottom="25dp"
app:horizontalPanEnabled="true"
app:verticalPanEnabled="true"
app:zoomEnabled="true" />
</androidx.constraintlayout.widget.ConstraintLayout>
<RelativeLayout
android:id="#+id/relativeLayout3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/zoom_surface"
app:layout_constraintBottom_toTopOf="#id/relativeLayout2"
tools:ignore="MissingConstraints">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rvList"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="15dp"
android:orientation="horizontal"
app:layout_constrainedHeight="true"/>
</RelativeLayout>
<RelativeLayout
android:id="#+id/relativeLayout2"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
<Button
android:id="#+id/quick_action_video_save_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:layout_marginTop="12dp"
android:layout_marginBottom="12dp"
android:layout_weight="1"
android:background="#drawable/button_bg_rounded_corners"
android:fontFamily="#font/adobe_clean_bold"
android:text="#string/save_share_option"
android:textColor="#color/white_alpha_80" />
</RelativeLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
It should look like this:
But this recyler-view while loading taking the whole space of the activity and one header also. Can you tell me what is wrong in this? Can recyler-view won't be able to host inside this view.

The issue is that you don't have a top to bottom of constraint and have set the height as match constraints.. However for layouts like this i have a few tips..
do the layouts first with constant heights like 200 dp or so and change them later
follow a top to bottom or a bottom to top approach that is one view at the top and everything else is done taking that as anchor
use constraint layouts throughout. You don't need any other layout type if you're using constraint layout
<androidx.constraintlayout.widget.ConstraintLayout
android:id="#+id/zoom_surface"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_marginStart="15dp"
android:layout_marginTop="30dp"
android:layout_marginEnd="15dp"
android:background="#drawable/rounded_rectangle_rect"
android:visibility="visible"
app:layout_constraintDimensionRatio="H,5:4"
app:layout_constraintEnd_toStartOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/quick_action_video_header_contatiner"
app:layout_constraintBottom_toTopOf=" ">add the suitable id
<com.otaliastudios.zoom.ZoomSurfaceView
android:id="#+id/surface_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginTop="25dp"
android:layout_marginBottom="25dp"
app:horizontalPanEnabled="true"
app:verticalPanEnabled="true"
app:zoomEnabled="true" />
</androidx.constraintlayout.widget.ConstraintLayout>

android - button is making the page background change to gray

Solved
I have a scroll view that has a Constraint Layout layout inside of it. I Have a button that is constraint to the bottom of the table but it seems to change the background below the table to gray. all other widgets that I have added do not have the same problem.
Screenshot of problem
I removed the inner code of the table as its not need
<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">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:id="#+id/imageView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:scaleType="centerCrop"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/gaapic" />
<androidx.cardview.widget.CardView
android:id="#+id/homecard"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:elevation="5dp"
app:cardBackgroundColor="#color/white"
app:cardCornerRadius="15dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.8"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/imageView3">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="12dp"
android:padding="12dp"
android:text="#string/recent_news"
android:textColor="#color/black"
android:textSize="20sp"
android:textStyle="bold" />
<TextView
android:id="#+id/tvhomePageDate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_weight="9"
android:gravity="center"
android:text="#string/publish_date"
android:textColor="#color/black"
android:textSize="14sp"
android:textStyle="bold" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="12dp"
android:lineSpacingMultiplier="1.5"
android:padding="12dp"
android:text="#string/in_news"
android:textSize="13sp" />
</LinearLayout>
</androidx.cardview.widget.CardView>
<TableLayout
android:id="#+id/tableLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:background="#android:color/white"
android:elevation="90dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/homecard">
<!-- Table Heading -->
<TableRow android:background="#color/teal_200">
</TableLayout>
<TextView
android:id="#+id/tvTimeCheck"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.092"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/tableLayout"
app:layout_constraintVertical_bias="0.589" />
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="Live"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/tableLayout"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</ScrollView>

Try adding the following to either your ScrollView or ConstraintLayout:
android:background="#android:color/white"

Solved:
I solved my problem by putting the table inside of another Constraint Layout. I don't know if that is best practice but it works for now. Thank you #Shn_Android_Dev

Have you tryed to add .setBackgroundDrawable(null) to you button inside your class?
Example:
yourButton.setBackgroundDrawable(null);

TextViews in ConstraintLayout not wrapping properly despite setting properties

For some strange reason, the TextViews in my ConstraintLayout won't budge to show all text and it appears to go over the screen's boundaries. I already tried using app:layout_constrainedWidth="true" with android:layout_width="wrap_content" but that didn't have any effect in changing the positioning, leading me to think what would happen to the '1C' and '1D' text views when I add longer text in those.
Current result
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="20dp"
app:cardUseCompatPadding="true"
android:background="#android:color/white">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:id="#+id/linearLayoutA"
android:padding="12dp"
android:foreground="?android:attr/selectableItemBackground">
<!--Constraint 1-->
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/constraintLayoutTitle"
android:layout_marginBottom="10dp">
<ImageView
android:id="#+id/ibA"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#mipmap/ic_launcher_round" />
<TextView
android:id="#+id/tvA"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
app:layout_constraintStart_toEndOf="#+id/ibA"
app:layout_constraintTop_toTopOf="parent"
app:layout_constrainedWidth="true"
style="#android:style/TextAppearance.Medium"/>
</androidx.constraintlayout.widget.ConstraintLayout>
<!--Constraint 2-->
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/constraintLayout">
<ImageView
android:id="#+id/ivA"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#mipmap/ic_launcher_round" />
<TextView
android:id="#+id/tvB"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
app:layout_constraintStart_toEndOf="#+id/ivA"
app:layout_constraintTop_toTopOf="#+id/ivA"
style="#android:style/TextAppearance.Medium"/>
<TextView
android:id="#+id/tvC"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginBottom="10dp"
android:layout_marginTop="10dp"
app:layout_constraintBottom_toTopOf="#+id/tvD"
app:layout_constraintStart_toEndOf="#+id/ivA"
app:layout_constraintTop_toBottomOf="#+id/tvB"
style="#android:style/TextAppearance.Medium"/>
<ImageView
android:id="#+id/ivD"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
app:layout_constraintEnd_toEndOf="#+id/ivA"
app:layout_constraintStart_toStartOf="#+id/ivA"
app:layout_constraintTop_toBottomOf="#+id/ivA"
app:layout_constraintTop_toTopOf="#+id/tvD"
app:srcCompat="#mipmap/ic_launcher_round" />
<TextView
android:id="#+id/tvD"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
app:layout_constraintStart_toEndOf="#+id/ivD"
app:layout_constraintTop_toBottomOf="#+id/tvC"
style="#android:style/TextAppearance.Medium"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</LinearLayout>
</androidx.cardview.widget.CardView>
Suraj Vaishnav's suggestion

Because there is no constraint from the right(or end) side, add this app:layout_constraintEnd_toEndOf="parent" to tvA,tvB and so on.
Update:
apply both constraints: start and end and set the width 0dp. here are the working properties for tvB:
<TextView
android:id="#+id/tvB"
app:layout_constraintStart_toEndOf="#+id/ivA"
android:layout_width="0dp"
app:layout_constraintEnd_toEndOf="parent"
...
I guess you can do the same things for tvC & tvD, let me know if you face any issue.

Recyclerview rows gets shrinked after notifydatasetchanged or after notifyItemChanged(position)

I have a recyclerview that takes a Arraylist as paramter. And when i am adding an image uri to one the objects variables of the list and then refreshing the recylerview
using
rv.notifydatasetchanged
then my code properly adds image to the imageview of the object whose uri variable i set but all the rows gets shrinked
and when i am doing
rv.notifyItemChanged(position)
then that row gets shrinked. And other remains same. I am not modifying width or height after refresh or notifydatasetchanged, thats why i am confused why its happening.
Here is my recylverview row:
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools">
<data>
<variable
name="feedbackData"
type="in.myapp.event_subscriber.models.MyData" />
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#color/white"
android:orientation="vertical">
<LinearLayout
android:id="#+id/ll_question"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:orientation="horizontal">
<TextView
android:id="#+id/tv_question_number"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:text="#{Integer.toString(feedbackData.questionNumber)}"
android:textColor="#color/black"
android:textSize="16sp"
android:textStyle="bold"
app:layout_constraintEnd_toStartOf="#id/tv_question" />
<TextView
android:id="#+id/tv_question"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginEnd="40dp"
android:text="#{feedbackData.question}"
android:textSize="16sp"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/tv_question_number"
app:layout_constraintTop_toTopOf="parent" />
</LinearLayout>
<EditText
android:id="#+id/et_answer"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="20dp"
android:layout_marginTop="20dp"
android:layout_marginEnd="20dp"
android:background="#drawable/stroke_rectangle_grey"
android:gravity="start"
android:hint="Write you answer here..."
android:lines="4"
android:paddingStart="10dp"
android:paddingTop="15dp"
android:text="#{feedbackData.answer.description}"
app:layout_constraintTop_toBottomOf="#id/ll_question" />
<LinearLayout
android:id="#+id/ll_action_attachment"
goneUnless="#{feedbackData.imageUri==null}"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="20dp"
android:layout_marginTop="20dp"
android:layout_marginEnd="20dp"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/et_answer">
<ImageView
android:layout_width="20dp"
android:layout_height="20dp"
android:src="#drawable/ic_attachment" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:text="Add attachment"
android:textSize="16sp" />
</LinearLayout>
<ImageView
android:id="#+id/iv_attached_image"
attachImage="#{feedbackData.imageUri}"
android:layout_width="200dp"
android:layout_height="200dp"
android:layout_marginStart="20dp"
android:layout_marginTop="10dp"
android:elevation="10dp"
android:scaleType="fitXY"
android:visibility="gone" />
<TextView
android:id="#+id/tv_image_attached_text"
goneUnless="#{feedbackData.imageUri!=null}"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="20dp"
android:layout_marginTop="5dp"
android:text="Image Attached Successfully"
android:textColor="#color/medium_aqua_marine"
android:visibility="gone" />
<View
android:layout_width="match_parent"
android:layout_height="40dp" />
<View
android:layout_width="match_parent"
android:layout_height="0.5dp"
android:layout_marginStart="20dp"
android:layout_marginEnd="20dp"
android:background="#color/grey" />
</LinearLayout>
</layout>
The first image shows my defualt recyclerview, but as soon as i add an image uri from my local storage to the list variable and then call notifydatasetchanged or notifyItemChanged(position), the thing in second image happens. Everything shrinks, even the textviews and divider and everything shrinks.
Code for my recylerview:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#color/white">
<TextView
android:id="#+id/tv_event_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="20dp"
android:layout_marginTop="10dp"
android:layout_marginEnd="20dp"
android:background="#color/white"
android:text="Technical corridor"
android:textSize="18sp"
android:textStyle="bold"
app:layout_constraintTop_toTopOf="parent" />
<View
android:id="#+id/divider"
android:layout_width="match_parent"
android:layout_height="1dp"
android:layout_marginStart="20dp"
android:layout_marginTop="10dp"
android:layout_marginEnd="20dp"
android:background="#color/grey"
app:layout_constraintTop_toBottomOf="#id/tv_event_name" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rv_subscriber_feedback"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_marginTop="20dp"
android:layout_marginBottom="20dp"
app:layout_constraintBottom_toTopOf="#id/btn_submit"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/divider"
tools:listitem="#layout/row_feedback" />
<Button
android:id="#+id/btn_submit"
android:layout_width="100dp"
android:layout_height="30dp"
android:layout_marginBottom="40dp"
android:background="#color/colorPrimary"
android:text="Submit"
android:textColor="#color/white"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

I will try to give some hints, might be because recyclerView recalculates views:
1) for your recycler view setHasFixedSize(true)
2) set a LinearLayoutManager to your recyclerView
3) keep using notifyDataSetChanged()
4) let your recyclerview be match_parent both width and height
See what happens.

Adding the imageview on which i was setting image and the textview which was only visible after image is set inside one more linearlayout worked. Now its not shrinking. Maybe now only that linearlayout is shrinking upto the width of imageview. I Dont know why this is happening. But atleast this worked and can be used for now.
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
goneUnless="#{feedbackData.imageUri!=null}"
android:orientation="vertical">
<ImageView
android:id="#+id/iv_attached_image"
attachImage="#{feedbackData.imageUri}"
android:layout_width="200dp"
android:layout_height="200dp"
android:layout_marginStart="20dp"
android:layout_marginTop="10dp"
android:elevation="10dp"
android:scaleType="fitXY"
android:visibility="gone" />
<TextView
android:id="#+id/tv_image_attached_text"
goneUnless="#{feedbackData.imageUri!=null}"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="20dp"
android:layout_marginTop="5dp"
android:text="Image Attached Successfully"
android:textColor="#color/medium_aqua_marine"
android:visibility="gone" />
</LinearLayout>

Can I put a Button to bottom of a ConstraintLayout inside ScrollView?

I have a ScrollView contains a ConstraintLayout. Inside the ConstraintLayout, I put many views with an attribute layout_constraintTop_toBottomOf to make a relation between the view and the view top of it, and I used layout_marginTop to put spaces between the views.
In my design, I have a Button that should be in the bottom of the layout and it cannot happen with the layout_marginTop because it should have a relation with the bottom of the ConstraintLayout.
Here's my code:
<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.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingTop="10dp"
android:paddingBottom="10dp">
<TextView
android:id="#+id/logo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:layout_margin="120dp"
android:text="Logo"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="#+id/un_et"
android:layout_width="match_parent"
android:layout_height="50dp"
android:layout_marginLeft="28dp"
android:layout_marginTop="25dp"
android:layout_marginRight="28dp"
android:gravity="center"
android:hint="User name"
android:textColor="#bebebe"
android:textCursorDrawable="#null"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#id/logo" />
<EditText
android:id="#+id/pw_et"
android:layout_width="match_parent"
android:layout_height="50dp"
android:layout_marginLeft="28dp"
android:layout_marginTop="13dp"
android:layout_marginRight="28dp"
android:gravity="center"
android:hint="Password"
android:inputType="textPassword"
android:textColor="#bebebe"
android:textCursorDrawable="#null"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="#id/un_et" />
<RelativeLayout
android:id="#+id/save_pw"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:paddingLeft="28dp"
android:paddingRight="28dp"
app:layout_constraintTop_toBottomOf="#id/pw_et">
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:buttonTint="#bebebe"
android:text="Save account"
android:textColor="#bebebe" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:text="Forget password?"
android:textColor="#a40000" />
</RelativeLayout>
<Button
android:id="#+id/btn"
android:layout_width="match_parent"
android:layout_height="50dp"
android:layout_marginLeft="28dp"
android:layout_marginTop="17dp"
android:layout_marginRight="28dp"
android:text="Login"
android:textAllCaps="false"
android:textColor="#FFFFFF"
app:layout_constraintTop_toBottomOf="#id/save_pw" />
<Button
android:id="#+id/btn2"
android:layout_width="match_parent"
android:layout_height="50dp"
android:text="Sign up"
android:textAllCaps="false"
android:textColor="#FFFFFF"
app:layout_constraintTop_toBottomOf="#id/btn" />
</android.support.constraint.ConstraintLayout>
</ScrollView>

Replace ScrollView with NestedScrollView & also add android:fillViewport="true" like 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">
// rest of code
<Button
android:id="#+id/btn2"
android:layout_width="match_parent"
android:layout_height="50dp"
android:text="Sign up"
android:textAllCaps="false"
android:textColor="#FFFFFF"
app:layout_constraintVertical_bias="1"
app:layout_constraintTop_toBottomOf="#id/btn"
app:layout_constraintBottom_toBottomOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.core.widget.NestedScrollView>

Just set this property to your button:
app:layout_constraintBottom_toBottomOf="parent"
Then add this to your last view this property:
app:layout_constraintBottom_toTopOf="#+id/button"
Also, add to your last view:
android:layout_marginBottom="height_of_button"
However, if you are adding a lot of views it would be better to populate them inside a RecyclerView using an Adapter. Decide what you want to do. Also, tell me if I understood your question correctly, it was a bit confusing.

I found one solution to keep the button at the bottom, doesn't matter is your text is dynamic, read about app:layout_constraintVertical_bias https://developer.android.com/reference/androidx/constraintlayout/widget/ConstraintLayout#Bias
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/text_gallery"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:textAlignment="center"
android:textSize="20sp"
android:text="Title"
app:layout_constraintTop_toTopOf="parent"/>
<androidx.core.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="0dp"
android:fillViewport="true"
app:layout_constraintTop_toBottomOf="#id/text_gallery"
app:layout_constraintBottom_toBottomOf="parent">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:isScrollContainer="true">
<androidx.appcompat.widget.AppCompatTextView
app:layout_constraintTop_toTopOf="parent"
android:id="#+id/texto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="30sp"
android:text=" Text \n Text" />
<androidx.appcompat.widget.AppCompatButton
android:id="#+id/button"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Buton1"
app:layout_constraintVertical_bias="1"
app:layout_constraintTop_toBottomOf="#+id/texto"
app:layout_constraintBottom_toBottomOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.core.widget.NestedScrollView>
</androidx.constraintlayout.widget.ConstraintLayout>