title: Inflating ConstraintLayout in another ConstraintLayout
body: <p>I want to put a ConstraintLayout programmaticly in another ConstraintLayout. But it does not show up, if I inflate it the way I did before with a RelativeLayout.</p>
  
  <p>Here's the code inner file inner_area.xml:</p>
  
  <pre><code>&lt;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:id="@+id/innerArea"
  android:layout_width="match_parent"
  android:layout_height="match_parent"&gt;
  
  
  &lt;ImageView
      android:id="@+id/grade_one"
      android:layout_width="0dp"
      android:layout_height="0dp"
      android:layout_marginBottom="0dp"
      android:layout_marginLeft="0dp"
      android:layout_marginRight="0dp"
      android:layout_marginTop="0dp"
      android:background="@drawable/onegreen"
      app:layout_constraintBottom_toTopOf="@+id/h1"
      app:layout_constraintHorizontal_bias="0.0"
      app:layout_constraintLeft_toLeftOf="parent"
      app:layout_constraintRight_toLeftOf="@+id/v1"
      app:layout_constraintTop_toTopOf="parent"
      app:layout_constraintVertical_bias="0.0"
      tools:layout_conversion_absoluteHeight="20dp"
      tools:layout_conversion_absoluteWidth="30dp"
      tools:layout_conversion_absoluteX="0dp"
      tools:layout_conversion_absoluteY="0dp" /&gt;
  
  &lt;ImageView
      android:id="@+id/grade_three"
      android:layout_width="0dp"
      android:layout_height="0dp"
      android:layout_marginBottom="0dp"
      android:layout_marginRight="0dp"
      android:layout_marginTop="0dp"
      android:background="@drawable/threelila"
      app:layout_constraintBottom_toTopOf="@+id/h2"
      app:layout_constraintHorizontal_bias="0.0"
      app:layout_constraintLeft_toLeftOf="parent"
      app:layout_constraintRight_toLeftOf="@+id/v1"
      app:layout_constraintTop_toTopOf="@+id/h1"
      app:layout_constraintVertical_bias="0.0"
      tools:layout_conversion_absoluteHeight="20dp"
      tools:layout_conversion_absoluteWidth="30dp"
      tools:layout_conversion_absoluteX="0dp"
      tools:layout_conversion_absoluteY="20dp" /&gt;
      .....
   &lt;/android.support.constraint.ConstraintLayout&gt;
  </code></pre>
  
  <p>Outer LayoutFile parent.xml:</p>
  
  <pre><code>   &lt;?xml version="1.0" encoding="utf-8"?&gt;
   &lt;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:orientation="vertical"
  android:id="@+id/parentView"
  android:background="@color/primary"&gt;
  
  &lt;/android.support.constraint.ConstraintLayout&gt;
  </code></pre>
  
  <p>Javacode:</p>
  
  <pre><code>    ViewGroup parentView = rootView.findViewById(R.id.parentView);
      final ConstraintLayout innerArea = (ConstraintLayout) inflater.inflate(R.layout.inner_area, container, false);
      parentView.addView(innerArea);
  </code></pre>
  
  <p>But when I change in the inner.xml the layout_width or layout_height of the innerArea to wrap_content or match_parent, nothing happens. But when I change to 2000dp the inner layout shows up.</p>
  
  <p>What am I doing wrong or missing?</p>