title: Recyclerview animation not working in activity
body: <p>i have an activity that contains 2 fragments</p>
  
  <p><code>StepsFragment</code> contains a Recyclerview but the Recyclerview's animation is not working  </p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="wrap_content"
      android:layout_height="400dp"
      android:background="#B3D1DB"
      tools:context=".StepsFragment"&gt;
  
      &lt;TextView
          android:id="@+id/inputEntred"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="TextView"
          android:visibility="invisible" /&gt;
  
      &lt;androidx.recyclerview.widget.RecyclerView
          android:id="@+id/RV"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:clipToPadding="false"
          android:layoutAnimation="@anim/layou_animation_fall_down"
          android:paddingTop="10dp"
          android:paddingBottom="30dp" /&gt;
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p><strong>layou-animation-fall-down</strong></p>
  
  <pre class="lang-xml prettyprint-override"><code>    &lt;layoutAnimation xmlns:android="http://schemas.android.com/apk/res/android"
          android:animation="@anim/fall_down"
           android:animationOrder="normal"
             android:delay="15%"&gt;
  </code></pre>
  
  <p></p>
  
  <p><strong>fall-down</strong></p>
  
  <pre class="lang-xml prettyprint-override"><code>   &lt;set xmlns:android="http://schemas.android.com/apk/res/android" android:duration="6000"&gt;
          &lt;translate
              android:fromYDelta="-20%"
              android:interpolator="@android:anim/accelerate_decelerate_interpolator"
              android:toYDelta="0"
              android:duration="1000" /&gt;
       &lt;alpha
       android:fromAlpha="0"
       android:interpolator="@android:anim/accelerate_decelerate_interpolator"
       android:toAlpha="3"
           android:duration="1000"
       /&gt;
    &lt;scale
        android:fromXScale="105%"
        android:fromYScale="105%"
        android:interpolator="@android:anim/accelerate_decelerate_interpolator"
        android:pivotX="50%"
        android:pivotY="50%"
        android:toXScale="100%"
        android:toYScale="100%" android:duration="1000"
        /&gt;
  &lt;/set&gt;
  </code></pre>
  
  <p><strong>activity layout</strong></p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;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=".Sorting_activity"&gt;
  
  
  &lt;RelativeLayout
      android:id="@+id/triLayout"
      android:layout_width="0dp"
      android:layout_height="300dp"
      app:layout_constraintBottom_toTopOf="@+id/stepsLayout"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintHorizontal_bias="0.0"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toTopOf="parent"
      app:layout_constraintVertical_bias="0.0"&gt;
  
  &lt;/RelativeLayout&gt;
  
  &lt;androidx.coordinatorlayout.widget.CoordinatorLayout
      android:id="@+id/stepsLayout"
      android:layout_width="0dp"
      android:layout_height="0dp"
      app:layout_constraintBottom_toBottomOf="parent"
      app:layout_constraintEnd_toEndOf="parent"
      app:layout_constraintStart_toStartOf="parent"
      app:layout_constraintTop_toBottomOf="@+id/triLayout"&gt;&lt;/androidx.coordinatorlayout.widget.CoordinatorLayout&gt;
  </code></pre>
  
  <p></p>
  
  <p><strong>StepsFragment</strong> </p>
  
  <pre class="lang-xml prettyprint-override"><code> public class StepsFragment extends Fragment  {
  
  
  private OnFragmentInteractionListener mListener;
  
  private static TextView inputEntred  ;
  private static RecyclerView RV ;
  private Handler mhandler = new Handler();
  
  
  public StepsFragment() {
      // Required empty public constructor
  }
  
  public void setTextView(String textentered){
      inputEntred.setText(textentered);
      String[] numberList = inputEntred.getText().toString().split(",");
      final Integer[] numbers = new Integer[numberList.length];
      SelectionSort m1 = new SelectionSort();
     ArrayList&lt;String&gt; mystepsList = m1.steps(numbers);// returns the steps numbers
      final StepListAdapter adapter = new StepListAdapter() ;
      RV.setAdapter(adapter);
  
      LinearLayoutManager llm = new LinearLayoutManager(getActivity());
      RV.setLayoutManager(llm);
  
          adapter.setList(mystepsList);
  
  }
  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
                           Bundle savedInstanceState) {
  
       View view =inflater.inflate(R.layout.fragment_steps, container, false);
        inputEntred  =view.findViewById(R.id.inputEntred);
         RV =view.findViewById(R.id.RV);
  
      return view;
  }
  
  @Override
  public void onAttach(Context context) {
      super.onAttach(context);
      if (context instanceof OnFragmentInteractionListener) {
          //   mListener = (OnFragmentInteractionListener) context;
      } else {
          throw new RuntimeException(context.toString()
                  + " must implement OnFragmentInteractionListener");
      }
  }
  public interface OnFragmentInteractionListener {
      // TODO: Update argument type and name
      void onFragmentInteraction(Uri uri);
  }}
  </code></pre>