Why is my recyclerview showing a whitespace

Question

I am practing recyclerView in a fragment in Android Studio, I made this Application;

As you can see there is a whitespace between the toolbar (appbar) and the contents (i.e the recyclerview in this case)

Please, how do I get rid of this whitespace..

Here's the .xml file of the fargment I put the recyclerview:

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    tools:context=".ui.newscreen.NewScreenFragment">

    <!-- TODO: Update blank fragment layout -->
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:listitem="@layout/new_screen_recyclerview_look" />

</androidx.constraintlayout.widget.ConstraintLayout>

Here's the sample layout listItem;

<androidx.constraintlayout.widget.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">


    <androidx.cardview.widget.CardView
        android:id="@+id/cardView"
        android:layout_width="150dp"
        android:layout_height="150dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="12dp"
        android:layout_marginEnd="8dp"
        android:layout_marginBottom="8dp"
        app:cardCornerRadius="8dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <ImageView
            android:id="@+id/card_image"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scaleType="fitXY"
            app:srcCompat="@drawable/nav_header_image_nature"
            android:contentDescription="@string/images_for_the_stories" />
    </androidx.cardview.widget.CardView>

    <TextView
        android:id="@+id/card_title"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginEnd="16dp"
        android:text="@string/Leonardo_Del_Vecchio"
        android:textSize="20sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="@+id/cardView"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/cardView"
        app:layout_constraintTop_toTopOf="@+id/cardView"
        app:layout_constraintVertical_bias="0.04000002" />

    <TextView
        android:id="@+id/card_tontent"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="8dp"
        android:layout_marginEnd="16dp"
        android:maxLines="3"
        android:text="@string/sample_story_content"
        android:textSize="18sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@+id/cardView"
        app:layout_constraintTop_toBottomOf="@+id/card_title" />


</androidx.constraintlayout.widget.ConstraintLayout>

Thanks in Advance for your Help!

Answer 1

I have been able to solve the issue.

There was a attribute in the main_activity.xml that cause this.

which was android:paddingTop="?attr/actionBarSize

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingTop="?attr/actionBarSize">