The layout of MainActivity is in the activity_main.xml file. Here, we have added RecyclerView to show the list, one FabButton to submit the post, and a TextView to show if there is no post available. Here is a piece of the code:

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
        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=".ui.MainActivity">
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<android.support.v7.widget.RecyclerView
 android:id="@+id/displayList"
 android:layout_width="0dp"
 android:layout_height="0dp"
 app:layout_constraintEnd_toEndOf="parent"
 app:layout_constraintStart_toStartOf="parent"
 tools:listitem="@layout/post_item"
 app:layout_constraintBottom_toBottomOf="parent"
 app:layout_constraintHorizontal_bias="0.0" android:layout_marginTop="8dp"
 app:layout_constraintTop_toBottomOf="@+id/appBarLayout"/>
 </android.support.constraint.ConstraintLayout>
     <android.support.design.widget.FloatingActionButton
     android:id="@+id/fabMain"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:layout_gravity="bottom|end"
     android:layout_margin="@dimen/fab_margin"
     app:srcCompat="@android:drawable/ic_dialog_email"/>
</android.support.design.widget.CoordinatorLayout>