RecycleView leaves empty space at the bottom because of toolbar

I assume there could be issue while adding new data and notify adapter.

You should change from notifyDataSetChanged() to notifyItemInserted(index).

More documentation on notifyItemInserted(index) here.

Hope it helps.

Can you please try the below layout file. I have tested it and it works fine. You can remove the marginButtom from the recyclerview as well.

xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior">


<androidx.coordinatorlayout.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">

<com.google.android.material.appbar.AppBarLayout
    android:id="@+id/summaryAppBar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <com.google.android.material.appbar.CollapsingToolbarLayout
        android:id="@+id/main.collapsing"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_scrollFlags="scroll|exitUntilCollapsed|snap">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="256dp"
            android:background="@drawable/fable_1"
            app:layout_collapseMode="parallax"
            app:layout_collapseParallaxMultiplier="0.3" />

        <!-- This is sticky header-->
        <androidx.appcompat.widget.Toolbar
            android:id="@+id/summaryToolBar"
            android:layout_width="match_parent"
            android:layout_height="72dp"
            android:layout_gravity="center"
            android:background="@android:color/white"
            android:padding="@dimen/common_layout_margin"
            android:visibility="visible"
            app:layout_collapseMode="pin"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light">

            <FrameLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content">

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:textSize="24sp"
                    android:text="Name" />

                <TextView
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="right"
                    android:textSize="24sp"
                    android:text="Offer"/>

            </FrameLayout>

        </androidx.appcompat.widget.Toolbar>

        </com.google.android.material.appbar.CollapsingToolbarLayout>

    </com.google.android.material.appbar.AppBarLayout>



    <androidx.recyclerview.widget.RecyclerView
    android:id="@+id/recyclerView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:clipToPadding="false"
    android:visibility="visible"
    android:layout_marginBottom="72dp"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:listItem="@layout/item_dessert" />

</androidx.coordinatorlayout.widget.CoordinatorLayout>
</RelativeLayout>

I believe that the CoordinatorLayout (maybe the AppBarLayout or CollapsingToolbarLayout - not sure which component) is recording the incorrect height of the CollapsingToolbarLayout due to the sticky toolbar. The behavior differs if items are added before or after the initial layout.

Try the following:

1. Remove android:layout_marginBottom="72dp" from the XML for the RecyclerView.
2. Add android:minHeight="72dp" to the XML for CollapsingToolbarLayout

Since your sticky toolbar is set at 72dp, it is OK to use minHeight set to 72dp.

If you have trouble with this, post back here.

---

Here is a quick demo of your layout using a NestedScrollView and the changes mentioned above.

Update: I have worked this out using RecyclerView which displays the same problem. Demo project showing the problem and the fix is on GitHub.

Here is the code:

MainActivity.java

public class MainActivity extends AppCompatActivity {  
    // Set to true to break the layout; false for it to work.  
    // The setting of this flag should only matter for the 
    // layout activity_not_working.  
    private boolean mBreakIt = true;  

    //    private int mLayoutToUse = R.layout.activity_not_working;  
    private int mLayoutToUse = R.layout.activity_working;  

    private LinearLayout mLayout;  

    @Override  
  protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(mLayoutToUse);  

        mLayout = findViewById(R.id.linearLayout);  
        if (mBreakIt) {  
            mLayout.post(new Runnable() {  
                @Override  
  public void run() {  
                    addViews();  
                }  
            });  
        } else {  
            addViews();  
        }  
    }  

    private void addViews() {  
        for (int i = 0; i < 50; i++) {  
            TextView tv = new TextView(MainActivity.this);  
            tv.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,  
                    ViewGroup.LayoutParams.WRAP_CONTENT));  
            tv.setText("TextView #" + (i + 1));  
            mLayout.addView(tv);  
        }  
    }  
}

activity_working.xml

<androidx.coordinatorlayout.widget.CoordinatorLayout 
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.google.android.material.appbar.AppBarLayout
        android:id="@+id/summaryAppBar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <com.google.android.material.appbar.CollapsingToolbarLayout
            android:id="@+id/main.collapsing"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:minHeight="72dp"
            app:layout_scrollFlags="scroll|exitUntilCollapsed|snap">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="256dp"
                android:background="@drawable/beach"
                app:layout_collapseMode="parallax"
                app:layout_collapseParallaxMultiplier="0.3" />

            <!-- This is sticky header-->
            <androidx.appcompat.widget.Toolbar
                android:id="@+id/summaryToolBar"
                android:layout_width="match_parent"
                android:layout_height="72dp"
                android:layout_gravity="center"
                android:background="@android:color/white"
                android:padding="@dimen/common_layout_margin"
                android:visibility="visible"
                app:layout_collapseMode="pin"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light">

                <FrameLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="Name"
                        android:textSize="24sp" />

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_gravity="right"
                        android:text="Offer"
                        android:textSize="24sp" />

                </FrameLayout>

            </androidx.appcompat.widget.Toolbar>

        </com.google.android.material.appbar.CollapsingToolbarLayout>

    </com.google.android.material.appbar.AppBarLayout>

    <!-- Bottom margin if I do't use then it does not display last child item. Wired but true in this case-->
    <!-- Removed following: -->
    <!--android:layout_marginBottom="72dp"-->

    <androidx.core.widget.NestedScrollView
        android:id="@+id/nestedScrollView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/holo_blue_light"
        android:visibility="visible"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        app:layout_insetEdge="bottom"
        tools:listItem="@layout/item_dessert">

        <LinearLayout
            android:id="@+id/linearLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="A TextView" />

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="A TextView" />

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="A TextView" />

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="A TextView" />


        </LinearLayout>
    </androidx.core.widget.NestedScrollView>

</androidx.coordinatorlayout.widget.CoordinatorLayout>

activity_not_working.xml

<androidx.coordinatorlayout.widget.CoordinatorLayout 
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.google.android.material.appbar.AppBarLayout
        android:id="@+id/summaryAppBar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <com.google.android.material.appbar.CollapsingToolbarLayout
            android:id="@+id/main.collapsing"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_scrollFlags="scroll|exitUntilCollapsed|snap">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="256dp"
                android:background="@drawable/beach"
                app:layout_collapseMode="parallax"
                app:layout_collapseParallaxMultiplier="0.3" />

            <!-- This is sticky header-->
            <androidx.appcompat.widget.Toolbar
                android:id="@+id/summaryToolBar"
                android:layout_width="match_parent"
                android:layout_height="72dp"
                android:layout_gravity="center"
                android:background="@android:color/white"
                android:padding="@dimen/common_layout_margin"
                android:visibility="visible"
                app:layout_collapseMode="pin"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light">

                <FrameLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:text="Name"
                        android:textSize="24sp" />

                    <TextView
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_gravity="right"
                        android:text="Offer"
                        android:textSize="24sp" />

                </FrameLayout>

            </androidx.appcompat.widget.Toolbar>

        </com.google.android.material.appbar.CollapsingToolbarLayout>

    </com.google.android.material.appbar.AppBarLayout>

    <!-- Bottom margin if I do't use then it does not display last child item. Wired but true in this case-->
    <!-- Removed following: -->
    <!--android:layout_marginBottom="72dp"-->

    <androidx.core.widget.NestedScrollView
        android:id="@+id/nestedScrollView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginBottom="72dp"
        android:background="@android:color/holo_blue_light"
        android:visibility="visible"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        app:layout_insetEdge="bottom"
        tools:listItem="@layout/item_dessert">

        <LinearLayout
            android:id="@+id/linearLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="A TextView" />

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="A TextView" />

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="A TextView" />

            <TextView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="A TextView" />


        </LinearLayout>
    </androidx.core.widget.NestedScrollView>

</androidx.coordinatorlayout.widget.CoordinatorLayout>

The RecyclerView height is just being calculated wrongfully, when entering scroll. these two different examples only added confusion to the question, without the least Java code provided.

simply remove this one line from the RecyclerView:

android:layout_marginBottom="72dp"

this attribute has little use, because it's the default value:

android:visibility="visible"

don't set the RecyclerView height like this:

android:layout_height="match_parent"

but make it fill up the available space:

android:layout_height="0dp"
android:layout_weight="1.00"

so that the RecyclerView would always fit, in case there is a toolbar present, whether or not - this toolbar just shouldn't be set sticky, because this is what demands halfheartedly "fixing" the layout. a BottomNavigationView might eventually be useful there, depending on what that toolbar, might be good for. even found the source of the script: CoordinatorBehaviorExample, which should have been attributed, as the license requires it.