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MonoDroid: Fragment.Instantiate ClassNotFoundException

I am trying to create a swipping tab view using ActionBar in Mono for Android.

The Adroid for the eclipse plugin has this as the default project template, and I managed to convert it, now I'm trying to add functionally to separate my fragments.

When I try to run my project, I get a ClassNotFoundException

Here is the code for the snippet

using Fragment = Android.Support.V4.App.Fragment; namespace MobileCompanion.AndroidOS.App.UI.Customers { public class HomeTab : Fragment { public override Android.Views.View OnCreateView(Android.Views.LayoutInflater inflater, Android.Views.ViewGroup viewGroup, Android.OS.Bundle p2) { return null; } } }

and here is my section adapter

 using System.Collections.Generic; using Android.Content; using Android.OS; using Android.Support.V4.App; using Java.Lang; namespace MobileCompanion.AndroidOS.App { public class SectionsPagerAdapter : FragmentPagerAdapter { private readonly Context _context; public readonly IList<TabInfo> Tabs = new List<TabInfo>(); private Bundle _bundle; public SectionsPagerAdapter(FragmentManager fm, Context context, Bundle savedInstanceState) : base(fm) { this._context = context; this._bundle = savedInstanceState; } public override Fragment GetItem(int i) { var args = new Bundle(); var page = Fragment.Instantiate(this._context, typeof(HomeTab).FullName); // var page = new HomeTab(); <<--- Work but nothing displayed as none of the create methods are run page.Arguments = args; return page; } public override int Count { get { return this.Tabs.Count; } } public override ICharSequence GetPageTitleFormatted(int p0) { return new String(this.Tabs[p0].PageTitle); } } }

Java.Lang.RuntimeException: Cannot instantiate MobileCompanion.AndroidOS.App.UI.Customers.HomeTab: make sure class name exists, is public, and has an empty constructor that is public on Android.Runtime.JNIEnv.CallStaticObjectMethod (intptr, intptr, Android.Runtime.JValue []) [0x00024] in / Users / builder / data / lanes / monodroid -mac-monodroid-4.2.4-branch / 9f7cbd60 / source / monodroid / src / Mono.Android / src / Runtime /JNIEnv.g.cs:767

on Android.Support.V4.App.Fragment.Instantiate (Android.Content.Context, string) [0x00034] in / Users / builder / data / lanes / monodroid -mac-monodroid-4.2.4-branch / 9f7cbd60 / source / monodroid-bindings / Compatibility-v4 / bindings / obj / platform-14 / src / generated / Android.Support.V4.App.Fragment.cs: 624

in MobileCompanion.AndroidOS.App.SectionsPagerAdapter.GetItem (int) [0x00007] in C: \ Projects \ MobileCompanion \ trunk \ MobileCompanion.Android.App \ SectionsPagerAdapter.cs: 28

on Android.Support.V4.App.FragmentPagerAdapter.n_GetItem_I (intptr, intptr, int) [0x00008] in / Users / builder / data / lanes / monodroid -mac-monodroid-4.2.4-branch / 9f7cbd60 / source / monodroid- bindings / Compatibility-v4 / bindings / obj / platform-14 / src / generated / Android.Support.V4.App.FragmentPagerAdapter.cs: 56

at (dynamic wrapper method) object.780b3637-f853-4d6e-8435-9c92bc6a9dd5 (intptr, intptr, int)

--- End of stack trace of managed exceptions ---

android.support.v4.app.Fragment $ InstantiationException: Unable to execute instance of MobileCompanion.AndroidOS.App.UI.Customers.HomeTab instance: make sure class name exists, is public and has an empty constructor that is public

  at android.support.v4.app.Fragment.instantiate(Fragment.java:395) at android.support.v4.app.Fragment.instantiate(Fragment.java:363) at

mobilecompanion.androidos.app.SectionsPagerAdapter.n_getItem (Native Method)

  at

mobilecompanion.androidos.app.SectionsPagerAdapter.getItem (SectionsPagerAdapter.java:30)

  at

android.support.v4.app.FragmentPagerAdapter.instantiateItem (FragmentPagerAdapter.java: 97)

  at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:692) at android.support.v4.view.ViewPager.populate(ViewPager.java:821) at android.support.v4.view.ViewPager.populate(ViewPager.java:772) at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1234) at android.view.View.measure(View.java:12723) at

android.view.ViewGroup.measureChildWithMargins (ViewGroup.java:4698)

  at android.widget.FrameLayout.onMeasure(FrameLayout.java:293) at android.view.View.measure(View.java:12723) at

android.widget.LinearLayout.measureVertical (LinearLayout.java:812)

  at android.widget.LinearLayout.onMeasure(LinearLayout.java:553) at android.view.View.measure(View.java:12723) at

android.view.ViewGroup.measureChildWithMargins (ViewGroup.java:4698)

  at android.widget.FrameLayout.onMeasure(FrameLayout.java:293) at

com.android.internal.policy.impl.PhoneWindow $ DecorView.onMeasure (PhoneWindow.java:2092)

  at android.view.View.measure(View.java:12723) at

android.view.ViewRootImpl.performTraversals (ViewRootImpl.java:1064)

  at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2442) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:4424) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at

com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run (ZygoteInit.java:784)

  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) at dalvik.system.NativeStart.main(Native Method)

Called: java.lang.ClassNotFoundException: MobileCompanion.AndroidOS.App.UI.Customers.HomeTab

  at

dalvik.system.BaseDexClassLoader.findClass (BaseDexClassLoader.java:61)

  at java.lang.ClassLoader.loadClass(ClassLoader.java:501) at java.lang.ClassLoader.loadClass(ClassLoader.java:461) at android.support.v4.app.Fragment.instantiate(Fragment.java:385)
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2 answers

For the namespace to work, there must be all lowercase letters for Fragment.Instantiate . I believe this restriction is carried over from Java.

 var page = Fragment.Instantiate(_activity, typeof(T).Namespace.ToLower() + "." + typeof(T).Name);
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The best answer:

 var page = Fragment.Instantiate (_activity, Java.Lang.Class.FromType(T).Name);
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