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>

Answer 2

Below example helps to understand this concept

Below are the constraints for text3

 app:layout_goneMarginStart="100dp"
 app:layout_constraintStart_toEndOf="@id/text2"
 android:layout_marginStart="10dp"

since we had set start constraint with text2 for text3

• when text2 is visible, android:layout_marginStart="10dp" will be considered
• when text2 is gone,app:layout_goneMarginStart="100dp" will be considered as text3 start constraint is with text2. So, when startConstraint is gone it considers goneMarginStart.Similarly,if endConstraint is gone, goneMarginEnd will be considered as below