keep the margin when the referenced view is gone in ConstraintLayout

Question

I have 2 TextViews as in the xml below. If I hide the textView2 at runtime, I lose the bottom margin. How can I keep the bottom margin between textView and parent to be 16dp when the textView2 is gone.

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content">

  <TextView
      android:id="@+id/textView"
      android:layout_width="0dp"
      android:layout_height="wrap_content"
      android:layout_marginBottom="16dp"
      android:layout_marginEnd="8dp"
      android:layout_marginStart="8dp"
      android:layout_marginTop="8dp"
      android:text="abc"
      app:layout_constraintBottom_toTopOf="@+id/textView2"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toTopOf="parent"
      app:layout_constraintVertical_chainStyle="packed"
      />

  <TextView
      android:id="@+id/textView2"
      android:layout_width="0dp"
      android:layout_height="wrap_content"
      android:layout_marginBottom="32dp"
      android:layout_marginEnd="8dp"
      android:layout_marginStart="8dp"
      android:text="xyz"
      app:layout_constraintBottom_toBottomOf="parent"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toBottomOf="@+id/textView"
      app:layout_constraintVertical_chainStyle="packed"/>
</android.support.constraint.ConstraintLayout>

Answer 1

Use layout_goneMarginBottom:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content">

  <TextView
      android:id="@+id/textView"
      android:layout_width="0dp"
      android:layout_height="wrap_content"
      android:layout_marginBottom="16dp"
      android:layout_marginEnd="8dp"
      android:layout_marginStart="8dp"
      android:layout_marginTop="8dp"
      android:text="abc"
      app:layout_goneMarginBottom="16dp"
      app:layout_constraintBottom_toTopOf="@+id/textView2"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toTopOf="parent"
      app:layout_constraintVertical_chainStyle="packed"
      />

  <TextView
      android:id="@+id/textView2"
      android:layout_width="0dp"
      android:layout_height="wrap_content"
      android:layout_marginBottom="32dp"
      android:layout_marginEnd="8dp"
      android:layout_marginStart="8dp"
      android:text="xyz"
      app:layout_constraintBottom_toBottomOf="parent"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toBottomOf="@+id/textView"
      app:layout_constraintVertical_chainStyle="packed"/>
</android.support.constraint.ConstraintLayout>