Develop Reference

About the constraint layout height

The below picture is the output I wanted to make:
I have already gone through
How to set a view's height match parent in ConstraintLayout?
and
https://developer.android.com/reference/android/support/constraint/ConstraintLayout
What I have done is I have made a constrain layout as the main parent layout and inside that, I had mad a relative layout with the circle as background and Image on top.
And also the rectangular top curved corners one is in the background of a constraint layout. Now what I am not getting is the height of this constraint layout the bottom of this should touch the bottom of the screen but as soon as I declare the height as match parent it occupies the whole screen from top to bottom. Below is my XML code.
<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/silver"
tools:context=".ResetPassword">
<RelativeLayout
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_marginLeft="20dp"
android:layout_marginStart="20dp"
android:layout_marginTop="20dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:background="#drawable/circle_shape"
>
<ImageView
android:id="#+id/iv_reset_bck"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:src="#drawable/ic_arrow_back_black_24dp"></ImageView>
</RelativeLayout>
<RelativeLayout
android:id="#+id/rl_reset_topImage"
android:layout_width="200dp"
android:layout_height="200dp"
android:layout_marginTop="40dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:background="#drawable/circle_shape">
<ImageView
android:id="#+id/iv_reset"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_alignParentBottom="true"
android:layout_marginBottom="20dp"
app:srcCompat="#mipmap/ic_launcher_round" />
</RelativeLayout>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:background="#drawable/bg_rectangle"
android:paddingLeft="5dp"
android:paddingTop="5dp"
android:paddingRight="5dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="#+id/rl_reset_topImage">
<LinearLayout
android:id="#+id/welcomeLoginLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
tools:layout_editor_absoluteY="5dp">
<com.example.portfolio.CustomViews.PopinsBoldTextView
android:id="#+id/tv_welcome"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="43dp"
android:layout_marginLeft="43dp"
android:layout_marginTop="44dp"
android:text="#string/welcome"
android:textColor="#color/black"
android:textSize="26sp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<com.example.portfolio.CustomViews.PopinsBoldTextView
android:id="#+id/tv_logintext_msg"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="43dp"
android:layout_marginLeft="43dp"
android:text="#string/loginwith"
android:textColor="#color/black"
android:textSize="20sp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</LinearLayout>
<RelativeLayout
android:id="#+id/emailRelativeLayout"
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_marginStart="40dp"
android:layout_marginLeft="40dp"
android:layout_marginTop="20dp"
android:layout_marginEnd="40dp"
android:layout_marginRight="40dp"
android:background="#drawable/bg_email_rect"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/welcomeLoginLayout">
<EditText
android:id="#+id/et_email"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginStart="20dp"
android:layout_marginLeft="20dp"
android:layout_marginEnd="20dp"
android:layout_marginRight="20dp"
android:background="#android:color/transparent"
android:hint="#string/prompt_email"
android:paddingTop="5dp"
android:textSize="20sp"
android:paddingBottom="5dp"
android:textColorHint="#color/dark_gey"></EditText>
</RelativeLayout>
<RelativeLayout
android:id="#+id/passwordlRelativeLayout"
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_marginStart="40dp"
android:layout_marginLeft="40dp"
android:layout_marginTop="20dp"
android:layout_marginEnd="40dp"
android:layout_marginRight="40dp"
android:background="#drawable/bg_email_rect"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/emailRelativeLayout">
<EditText
android:id="#+id/et_password"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginStart="20dp"
android:layout_marginLeft="20dp"
android:layout_marginEnd="20dp"
android:layout_marginRight="20dp"
android:background="#android:color/transparent"
android:hint="#string/prompt_password"
android:textSize="20sp"
android:paddingTop="5dp"
android:paddingBottom="5dp"
android:textColorHint="#color/dark_gey"></EditText>
</RelativeLayout>
<RelativeLayout
android:id="#+id/login_btnLayout"
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_marginStart="40dp"
android:layout_marginLeft="40dp"
android:layout_marginTop="20dp"
android:layout_marginEnd="40dp"
android:layout_marginRight="40dp"
android:background="#drawable/bg_btn"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/passwordlRelativeLayout">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:text="Login"
android:textColor="#FFF"
android:textSize="20dp"
android:textStyle="bold"></TextView>
</RelativeLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
This is what I get the output from the above code
How can I make it as the above image?

As mentioned in the comment, you do not need to setup parent Layouts inside ConstraintLayout as ConstraintLayout is pretty powerful and can easily achieve what you want. What you are lacking is good use of constraints, and you are trying to compensate that by using RelativeLayout. Having a ConstraintLayout inside a ConstraintLayout is an overkill.
I have not created the BottomSheet for you ResetPassword, but that is something you can work on yourself as its simply an arrangement of elements or bringing in a customView. My point is to simply use one ConstraintLayout as the parent that will manage all the ViewGroups, and refrain from using any other Layouts inside it.
Design preview
XML Layout 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">
<ImageView
android:id="#+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.25"
tools:srcCompat="#tools:sample/avatars" />
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="100dp"
android:text="Reset your password"
app:layout_constraintEnd_toEndOf="#+id/imageView2"
app:layout_constraintStart_toStartOf="#+id/imageView2"
app:layout_constraintTop_toBottomOf="#+id/imageView2" />
<TextView
android:id="#+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="Reset your password to use app"
app:layout_constraintEnd_toEndOf="#+id/textView"
app:layout_constraintStart_toStartOf="#+id/textView"
app:layout_constraintTop_toBottomOf="#+id/textView" />
<EditText
android:id="#+id/editTextTextPersonName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="100dp"
android:ems="10"
android:inputType="textPersonName"
android:text="Name"
app:layout_constraintEnd_toEndOf="#+id/textView2"
app:layout_constraintStart_toStartOf="#+id/textView2"
app:layout_constraintTop_toBottomOf="#+id/textView2" />
<EditText
android:id="#+id/editTextTextPassword"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:ems="10"
android:hint="Password"
android:inputType="textPassword"
app:layout_constraintEnd_toEndOf="#+id/editTextTextPersonName"
app:layout_constraintStart_toStartOf="#+id/editTextTextPersonName"
app:layout_constraintTop_toBottomOf="#+id/editTextTextPersonName" />
<Button
android:id="#+id/button"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="Button"
app:layout_constraintEnd_toEndOf="#+id/editTextTextPassword"
app:layout_constraintStart_toStartOf="#+id/editTextTextPassword"
app:layout_constraintTop_toBottomOf="#+id/editTextTextPassword" />
</androidx.constraintlayout.widget.ConstraintLayout>

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>

Why do the buttons goes up?

So I programmed a simple app with android studio and the layout that is shown in the app when I run it is different than the xml file I designed.
Here is a link of an image of the problem.
https://imgur.com/6JIHSQ7
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<Button
android:id="#+id/subBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/subBtn"
android:textSize="30sp"
app:layout_constraintBaseline_toBaselineOf="#+id/addBtn"
app:layout_constraintStart_toStartOf="#+id/divBtn" />
<Button
android:id="#+id/addBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="36dp"
android:layout_marginLeft="36dp"
android:layout_marginBottom="42dp"
android:text="#string/addBtn"
android:textSize="30sp"
app:layout_constraintBottom_toTopOf="#+id/multBtn"
app:layout_constraintStart_toEndOf="#+id/subBtn" />
<EditText
android:id="#+id/n1EditText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="56dp"
android:ems="10"
android:hint="#string/number1"
android:inputType="textPersonName"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.444"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="#+id/n2EditText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="39dp"
android:ems="10"
android:hint="#string/number2"
android:inputType="textPersonName"
app:layout_constraintStart_toStartOf="#+id/n1EditText"
app:layout_constraintTop_toBottomOf="#+id/n1EditText" />
<Button
android:id="#+id/multBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="108dp"
android:layout_marginRight="108dp"
android:layout_marginBottom="336dp"
android:text="#string/multBtn"
android:textSize="30sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent" />
<Button
android:id="#+id/divBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="88dp"
android:layout_marginLeft="88dp"
android:layout_marginBottom="336dp"
android:text="#string/divBtn"
android:textSize="30sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<TextView
android:id="#+id/resultTextView"
android:layout_width="174dp"
android:layout_height="73dp"
android:layout_marginTop="8dp"
android:layout_marginBottom="8dp"
android:background="#color/colorPrimaryDark"
android:text="#string/resultView"
android:textColor="#color/colorPrimary"
android:textSize="50sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.455"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/n2EditText"
app:layout_constraintVertical_bias="0.637" />
</androidx.constraintlayout.widget.ConstraintLayout>
I think it might be related to the virtual device i'm using but I don't know if that's the problem.

The problem is, your addBtn and subBtn are not aware of the n2EditText. The addBtn depends on the divBtn and the divBtn is placed 336dp above the bottom edge of the screen.
If you need the addBtn to appear below the n2EditText then you need to add a vertical constraint connecting to the n2EditText. Once your buttons are connected to their immediate top elements, you don't need to add the bottom constraint to the bottom edge of the screen.
Imagine a ConstraintLayout as a collection of widgets hanging down from the top of the screen, each tied to the immediately top elements with the chains called "constraints". You don't need to tie the bottom widget to the ground unless it is required by design.
Here is the modified layout:
<?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">
<Button
android:id="#+id/subBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="-"
android:textSize="30sp"
android:layout_marginTop="16dp"
app:layout_constraintTop_toBottomOf="#+id/n2EditText"
app:layout_constraintStart_toStartOf="#+id/n2EditText"/>
<Button
android:id="#+id/addBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="+"
android:textSize="30sp"
app:layout_constraintStart_toEndOf="#+id/subBtn"
app:layout_constraintTop_toTopOf="#+id/subBtn"
android:layout_marginStart="16dp"/>
<EditText
android:id="#+id/n1EditText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="56dp"
android:ems="10"
android:hint="n1"
android:inputType="textPersonName"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="#+id/n2EditText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:ems="10"
android:hint="n2"
android:inputType="textPersonName"
app:layout_constraintStart_toStartOf="#+id/n1EditText"
app:layout_constraintTop_toBottomOf="#+id/n1EditText"/>
<Button
android:id="#+id/multBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="*"
android:textSize="30sp"
app:layout_constraintStart_toEndOf="#+id/divBtn"
android:layout_marginStart="16dp"
app:layout_constraintTop_toTopOf="#+id/divBtn"/>
<Button
android:id="#+id/divBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="/"
android:textSize="30sp"
app:layout_constraintStart_toStartOf="#+id/subBtn"
android:layout_marginTop="8dp"
app:layout_constraintTop_toBottomOf="#+id/subBtn"/>
<TextView
android:id="#+id/resultTextView"
android:layout_width="174dp"
android:layout_height="73dp"
android:layout_marginBottom="8dp"
android:background="#color/colorPrimaryDark"
android:text="res"
android:textColor="#color/colorPrimary"
android:textSize="50sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
android:layout_marginTop="8dp" app:layout_constraintTop_toBottomOf="#+id/divBtn"/>
</androidx.constraintlayout.widget.ConstraintLayout>
Anyway, when you have a lot of widgets, you may have to use a ScrollView to accommodate them all.

Try this
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<Button
android:id="#+id/subBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginLeft="16dp"
android:layout_marginTop="52dp"
android:layout_marginEnd="25dp"
android:layout_marginRight="25dp"
android:text="submit"
android:textSize="30sp"
app:layout_constraintEnd_toStartOf="#+id/addBtn"
app:layout_constraintHorizontal_chainStyle="packed"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/n2EditText" />
<Button
android:id="#+id/addBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="52dp"
android:text="add"
android:textSize="30sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/subBtn"
app:layout_constraintTop_toBottomOf="#+id/n2EditText" />
<EditText
android:id="#+id/n1EditText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="52dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:ems="10"
android:hint="1"
android:inputType="textPersonName"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.439"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<EditText
android:id="#+id/n2EditText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="2dp"
android:layout_marginLeft="2dp"
android:layout_marginTop="36dp"
android:ems="10"
android:hint="2"
android:inputType="textPersonName"
app:layout_constraintStart_toStartOf="#+id/n1EditText"
app:layout_constraintTop_toBottomOf="#+id/n1EditText" />
<Button
android:id="#+id/multBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="44dp"
android:text="mult"
android:textSize="30sp"
app:layout_constraintStart_toEndOf="#+id/subBtn"
app:layout_constraintTop_toBottomOf="#+id/addBtn" />
<Button
android:id="#+id/divBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="44dp"
android:layout_marginEnd="48dp"
android:layout_marginRight="48dp"
android:text="div"
android:textSize="30sp"
app:layout_constraintEnd_toEndOf="#+id/subBtn"
app:layout_constraintTop_toBottomOf="#+id/subBtn" />
<TextView
android:id="#+id/resultTextView"
android:layout_width="174dp"
android:layout_height="73dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="48dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:background="#color/colorPrimaryDark"
android:text="resultView"
android:textColor="#color/colorPrimary"
android:textSize="50sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.547"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/divBtn" />
</androidx.constraintlayout.widget.ConstraintLayout>

Probably on your layout editor and phone screen sizes are different. Use ConstraintLayout or some other add constraints to views

I cannot say definitly just looking at image but i think you are using facing problem because of your layout. Use LinearLayout to fix it.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical" />
<!-- EditText: number1 -->
<!-- EditText Number2 -->
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<!-- 2 Buttons here -->
<LinearLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<!-- 2 Buttons here -->
</LinearLayout>
</LinearLayout>

Some general tips that can help:
Check the constraints if you're using ConstraintLayout or relatives between view if you're using RelativeLayout;
Check the values and the units of views;
Check the screen resolution of your "Preview" pane and Emulator.
If it's possible to provide some additional information about the layout that is used, if these tips didn't help.
In preview pane you can find info about resolutions here:
In the emulator pane you can simple see the sizes in the column:

ListView under constraint layout disappears in preview

Output png
So below is my xml for the activity:
I have migrated to androidx from support libraries.
Is there a way to achieve this?
<?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">
<AutoCompleteTextView
android:id="#+id/partyname"
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="#drawable/rounded_edittext"
android:layout_marginBottom="8dp"
android:layout_marginEnd="5dp"
android:layout_marginStart="5dp"
android:hint="#string/firm_name"
android:padding="5dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
<LinearLayout
android:id="#+id/billform"
android:layout_marginTop="5dp"
android:layout_marginRight="5dp"
android:layout_marginEnd="5dp"
android:layout_marginStart="5dp"
android:layout_marginLeft="5dp"
android:layout_width="match_parent"
android:layout_height="0dp"
android:orientation="vertical"
android:background="#drawable/rounded_buttons"
app:layout_constraintTop_toBottomOf="#id/partyname">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<AutoCompleteTextView
android:id="#+id/identifier"
android:layout_height="50dp"
android:layout_width="0dp"
android:padding="5dp"
android:layout_marginEnd="8dp"
android:textSize="16sp"
android:textAllCaps="true"
android:hint="#string/code_article"
android:background="#drawable/rounded_edittext"
android:layout_marginRight="8dp"
android:layout_alignParentStart="true"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:layout_toLeftOf="#+id/add"
android:layout_toStartOf="#+id/add" />
<Button
android:id="#+id/add"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/rounded_buttons"
android:text="#string/add"
android:textAllCaps="true"
android:textSize="18sp"
android:layout_centerVertical="true"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true" />
</RelativeLayout>
</LinearLayout>
<ListView
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintTop_toBottomOf="#id/billform"
app:layout_constraintBottom_toBottomOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
For god knows why, the listView is not available in the preview.
It works when the root is linear layout. I tried creating a linear layout within the constraint layout, it didn't work

android:layout_height="0dp"
That might be your problem or if you are talking about not seeing items then it might be a bug in android studio because I tried adding another ConstraintLayout without getting any luck.
This answer might help
I wanted to add my answer as a comment but StackOverflow won't let me.

Try to remove the nested layouts.
Try the below code
<?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">
<AutoCompleteTextView
android:id="#+id/partyname"
android:layout_width="match_parent"
android:layout_height="50dp"
android:layout_marginTop="24dp"
android:padding="5dp"
app:layout_constraintTop_toTopOf="parent"
tools:layout_editor_absoluteX="0dp" />
<AutoCompleteTextView
android:id="#+id/identifier"
android:layout_width="0dp"
android:layout_height="50dp"
android:layout_alignParentStart="true"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:layout_toStartOf="#+id/add"
android:layout_toLeftOf="#+id/add"
android:padding="5dp"
android:textAllCaps="true"
android:textSize="16sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/partyname" />
<Button
android:id="#+id/add"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:text="ADD"
android:textAllCaps="true"
android:textSize="18sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/identifier" />
<ListView
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="#+id/add" />

change the width from match_parent to 0dp and you can create left and right constraint.The following will work for you.
<ListView
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#id/billform"
app:layout_constraintBottom_toBottomOf="parent"/>
Update
<?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"
xmlns:tools="http://schemas.android.com/tools">
<AutoCompleteTextView
android:id="#+id/partyname"
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="#drawable/rounded_edittext"
android:layout_marginBottom="8dp"
android:layout_marginEnd="5dp"
android:layout_marginStart="5dp"
android:hint="#string/firm_name"
android:padding="5dp"
app:layout_constraintTop_toTopOf="parent"/>
<AutoCompleteTextView
android:id="#+id/identifier"
android:layout_height="50dp"
android:layout_width="0dp"
android:padding="5dp"
android:textSize="16sp"
android:textAllCaps="true"
android:hint="#string/code_article"
android:background="#drawable/rounded_edittext"
android:layout_toStartOf="#+id/add"
app:layout_constraintEnd_toStartOf="#+id/add"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/partyname"/>
<Button
android:id="#+id/add"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:background="#drawable/rounded_buttons"
android:text="#string/add"
android:textAllCaps="true"
android:textSize="18sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/partyname"/>
<ListView
android:layout_width="0dp"
android:layout_height="0dp"
tools:listitem="Add items here"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#id/add"
app:layout_constraintBottom_toBottomOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>

Space removal on the left of image in Xml file in android studio using the recycler view

I have two images that are beside textviews.
Now the problem with this UI is that the images must be aligned to complete left side, as if coming out or sticking to the edge of the screen. However, that's not the case. I have tried scaleType and adjustViewBound, but both of them didn't work. The xml file contents have been shown below.
<?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"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
<TextView
android:id="#+id/textView_subtopic_title"
android:layout_width="245dp"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignParentRight="true"
android:layout_alignTop="#+id/imageView_bulb"
android:layout_marginEnd="43dp"
android:layout_marginRight="43dp"
android:gravity="center"
android:text="Subtopic Title"
app:layout_constraintEnd_toEndOf="parent"
tools:ignore="MissingConstraints"
tools:layout_editor_absoluteY="64dp" />
<TextView
android:id="#+id/textView_count"
android:layout_width="91dp"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_below="#+id/textView_subtopic_title"
android:layout_marginLeft="135dp"
android:layout_marginStart="135dp"
android:text="Count"
app:layout_constraintEnd_toEndOf="parent"
tools:ignore="MissingConstraints"
tools:layout_editor_absoluteY="83dp" />
<ImageView
android:id="#+id/imageView_bulb"
android:layout_width="70dp"
android:layout_height="81dp"
android:layout_marginBottom="8dp"
android:layout_marginTop="64dp"
android:adjustViewBounds="true"
android:scaleType="fitXY"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/bulb_on" />
<ProgressBar
android:id="#+id/progressBar"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="128dp"
android:layout_height="wrap_content"
android:layout_alignBottom="#+id/imageView_bulb"
android:layout_centerHorizontal="true"
android:outlineAmbientShadowColor="#color/colorPrimary"
android:outlineSpotShadowColor="#color/colorAccent"
app:layout_constraintEnd_toEndOf="parent"
tools:ignore="MissingConstraints"
tools:layout_editor_absoluteY="114dp" />
<TextView
android:id="#+id/textView_topic_title"
android:layout_width="242dp"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginLeft="52dp"
android:layout_marginStart="52dp"
android:layout_marginTop="23dp"
android:text="Topic Title" />
<ImageView
android:id="#+id/imageView"
android:layout_width="16dp"
android:layout_height="41dp"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginStart="0dp"
android:layout_marginTop="9dp"
android:adjustViewBounds="true"
android:scaleType="fitXY"
app:srcCompat="#drawable/blue"
android:layout_alignParentLeft="true"
android:layout_marginLeft="0dp" />
</RelativeLayout>
What should be done to remove the space on the left of the images as shown in the image?

One way you could do it is set negative margin:
android:layout_marginStart="-10dp"
or
android:paddingStart="-10dp"
change -10 to what suits you.
<ImageView
android:id="#+id/imageView"
android:layout_width="16dp"
android:layout_height="41dp"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginStart="-10dp"
android:layout_marginTop="9dp"
android:adjustViewBounds="true"
android:scaleType="fitXY"
app:srcCompat="#drawable/nodata"/>

I got the solution to this problem. It basically lay with the activity_main.xml. The recyclerview in this xml had a left padding. I just removed it, made it 0. The snippet is shown below.
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#mipmap/bg"
tools:context=".MainActivity">
<android.support.v7.widget.RecyclerView
android:id="#+id/recyclerview_Main"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginBottom="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
I reduced the left margin to be zero in the attributes of the recyclerview.