Xamarin Android Global Session Variables - Error No constructor found (System.IntPtr, Android.Runtime.JniHandleOwnership) - variables

Question

I'm working with Xamarin Android on Xamarin Studio 5.5.3, Im trying to create a global session state using the sample on this link:
Login Session - Activities
My code is pretty similar as the one on the link.
My Application Class:
namespace MyApp.Library.Droid
{
public class SessionApplication : Application
{
private static int _userID;
private static string _email;
private static string _firstName;
private static string _lastName;
public override void OnCreate() {
base.OnCreate();
_userID=0;
_email=null;
_firstName = null;
_lastName = null;
}
public static int UserID
{
get { retu`enter code here`rn _userID; }
set { _userID=value; }
}
public static string Email
{
get { return _email; }
set { _email=value; }
}
public static string FirstName
{
get { return _firstName; }
set { _firstName=value; }
}
public static string LastName
{
get { return _lastName; }
set { _lastName=value; }
}
}
}
My Android Manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
android:versionCode="1"
android:versionName="1.0"
package="myapp.ui.droid">
<uses-sdk />
<application android:label="myapp.ui.droid" android:name="myapp.library.droid.SessionApplication">
</application>
</manifest>
my code compiles but then it runs throws this exception.
[MonoDroid] UNHANDLED EXCEPTION:
[MonoDroid] System.NotSupportedException: Unable to activate instance of type MyApp.Library.Droid.SessionApplication from native handle a2600019 --->
System.MissingMethodException: No constructor found for MyApp.Library.Droid.SessionApplication::.ctor(System.IntPtr, Android.Runtime.JniHandleOwnership) --->
Java.Interop.JavaLocationException: Exception of type 'Java.Interop.JavaLocationException' was thrown.
I'll appreciate your help.

Answer 1

Congratulations, you've found one of the few cases where you need to provide an explicit constructor that handles when a Java object is exposed to managed (Mono) code.
From the docs:
There are two scenarios in which the (IntPtr, JniHandleOwnership) constructor must be manually provided on a Managed Callable Wrapper subclass:
1 - Android.App.Application is subclassed. Application is special; the default Applicaton constructor will never be invoked, and the (IntPtr, JniHandleOwnership) constructor must instead be provided .
Virtual method invocation from a base class constructor.
To fix this, provide a constructor with the (IntPtr handle, JniHandleOwnership transfer) signature.
[Application]
public class SessionApplication : Application
{
public SessionApplication(IntPtr javaReference, JniHandleOwnership transfer)
:base(javaReference, transfer)
{
}
// ...
}
Some background reading:
Android Callable Wrappers
Xamarin.Android Architecture (See Java Activation specifically).