布局边距不适用于 RecyclerView 中的约束布局

Question

I am attempting to add spacing between views in the RecyclerView. Using the RecyclerView I have a repeating list of constraint views using a view adapter. On each constraint view I have set the layout margin to equal 15dp like so android:layout_margin="15dp" . When previewing the layout in design view I can see that the margin is being applied however when the app is compiled the RecyclerView.

The XML for the view being used inside the RecyclerView is as follows:

<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="wrap_content"
android:layout_margin="15dp"
android:background="@drawable/gradient"
android:clipToPadding="true"
android:minHeight="0dp">

<TextView
    android:id="@+id/moment_timestamp"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginStart="20dp"
    android:layout_marginTop="16dp"
    android:text="28 MAR @ 2:45pm"
    android:textColor="@android:color/white"
    app:layout_constraintEnd_toStartOf="@+id/moment_text"
    app:layout_constraintHorizontal_bias="0.0"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

<TextView
    android:id="@+id/moment_text"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_marginBottom="20dp"
    android:layout_marginEnd="20dp"
    android:layout_marginStart="20dp"
    android:layout_marginTop="40dp"
    android:background="@android:color/transparent"
    android:includeFontPadding="false"
    android:paddingVertical="0dp"
    android:text="A kind man held the door  open for me today"
    android:textAlignment="viewStart"
    android:textColor="@android:color/white"
    android:textSize="25sp"
    android:textStyle="bold"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toBottomOf="@+id/moment_timestamp" />

</android.support.constraint.ConstraintLayout>

In design view, the component I am designing looks like this:

However, when compiled and being used in the RecyclerView, the margins are not applied:

This is my code where I inflate the layout. Originally the width of the view was not being applied so as shown in this answer I changed my code.

View view = inflater.inflate(R.layout.text_moment, null, false);
RecyclerView.LayoutParams lp = new 
RecyclerView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
view.setLayoutParams(lp);
return new MomentViewHolder(view);

Searched around quite extensively now and can't seem to find a solution.

Answer 1

Try to to this:

<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="wrap_content"
android:layout_marginBottom="15dp" //This line is the important one
android:background="@drawable/gradient"
android:clipToPadding="true"
android:minHeight="0dp">

Or what i always do:

<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="wrap_content"
android:padding="16dp" //This line is the important one
android:background="@drawable/gradient"
android:clipToPadding="true"
android:minHeight="0dp">

Answer 2

I've managed to figure out the solution. It turns out the answer that I followed to try and resolve the width issue was causing the margin issue. Instead of setting null as the ViewGroup parameter on the inflate function, I have now passed ViewGroup into the inflate function like so:

View view = inflater.inflate(R.layout.text_moment, viewGroup, false);