so i downloaded monodevelop...and it installed xamarin studio 5.0.1...the gtkc# is working well...i made an app and run it...everything went well...when i tried to make an android app with c# thru new solution it said the "MainActivity.cs" couldn't be found.I let the default location in documents/projects and named the solution hello.I also have installed the android development add-in from add-in manager.I can't figure out what's the problem...also i had installed the android tools from eclipse.
I think it has something to do with the licensing, as XamarinStudio + Android / iOS is not a free product. I believe that the "re-branded-as-XamarinStudio" MonoDevelop available from the MonoDevelop website is simply missing the stuff needed to create these types of projects.
While I'd be interested in knowing why MonoDevelop has released a crippled (read broken) version of XamarinStudio, one can simply get the fully-functional "XamarinStudio" from the XamarinStudio website, and it will be able to create these project types without this issue (so long as you have a trial, or full license).
It will still be able to create other types of C# projects, just as MonoDevelop used to, as this whole thing is part of the process of moving away from the MonoDevelop name, and having a single product "XamarinStudio".