CustomComponent FindViewById from referenced project returns null - xamarin.android

Question

In C# Xamarin Android projects, I am trying to create a custom compound component to select a month. This extends LinearLayout.
I expect to re-use it (and keep my main project more tidy), so I have 2 projects - my main/parent project, containing my Activity and multiple Fragments; and a simple Android project for my component.
When I run the component project directly using its own Activity, it works as expected, but when I reference it from my main project, my FindViewById return null.
I can see that this and context are from the main project - and I would like to understand what I've done wrong or what I need to add so that it finds the component's layout and controls to inflate?
Main view (Ui.DateScrollPicker.Droid is my component's namespace and ScrollMonthPicker my class):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="10dp"
android:paddingRight="10dp">
.......
<ui.datescrollpicker.droid.ScrollMonthPicker
android:id="#+id/my_scroll_month_picker"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
Referenced from a Android.Support.V4.App.Fragment in the override View OnCreateView method:
scrollMonthPicker = view.FindViewById<ScrollMonthPicker>(Resource.Id.scroll_month_picker);
scrollMonthPicker.DateChanged += DatePicker_Changed;
By extending LinearLayout, I am implementing 2 constructors, including, ScrollMonthPicker(Context context, IAttributeSet attrs) : base(context, attrs, 0) which is called, and goes off to inflate my component's layout.
Component view (scroll_month_layout.axml):
<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<TextView
android:id="#+id/month_current_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Month" />
<TextView
android:id="#+id/year_current_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Year" />
<android.support.v7.widget.RecyclerView
android:id="#+id/month_recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</merge>
ScrollMonthPicker constructor:
public ScrollMonthPicker(Context context, IAttributeSet attrs)
: base(context, attrs, 0)
{
InflateLayout(context, attrs);
}
ScrollMonthPicker inflating view:
private void InflateLayout(Context context, IAttributeSet attrs)
{
var inflater = LayoutInflater.FromContext(this.Context);
inflater.Inflate(Resource.Layout.scroll_month_layout, this);
monthCurrentText = FindViewById<TextView>(Resource.Id.month_current_text);
yearCurrentText = FindViewById<TextView>(Resource.Id.year_current_text);
monthRecyclerView = FindViewById<RecyclerView>(Resource.Id.month_recycler_view);
monthRecyclerView.HasFixedSize = true;
......
}
The component works fine when called from 'its own' Activity, but all FindViewById are null (monthCurrentText, yearCurrentText and monthRecyclerView) when referenced by the fragment in the main project.
If I wait for the exception to be thrown in the main fragment from monthRecyclerView.HasFixedSize, I do not get a null reference exception, but this one:
Unhandled Exception:
System.NotSupportedException: Could not activate JNI Handle 0x7fff30d40b00 (key_handle 0x8f4c53e) of Java type 'md53fd9f663a5e8ddcd0a5da1b57d05fd99/ScrollMonthPicker' as managed type 'Ui.DateScrollPicker.Droid.ScrollMonthPicker'.
How do I make it populate as expected by referencing from a separate project??
Many thanks.

Answer 1

It seems your both projects are the android project. You could not use another android project code in one project. I think you need to create your CustomComponent project as a library.