Xamarin Android-找不到类型或名称空间“上下文”

Question

I'm following this Xamarin tutorial. Visual Studio throws an error when I use the "Context" class in my Android project. Shouldn't this class be included in my Android app by default?

Also, I defined an interface named "IStreamLoader" in a Portable Class Library called "Portable", and added a reference to "Portable" in my Android project. But referencing "IStreamLoader" in my Android project throws another error.

Are these two errors related?

Errors

CS0246  The type or namespace name 'IStreamLoader' could not be found (are you missing a using directive or an assembly reference?)

CS0246  The type or namespace name 'Context' could not be found (are you missing a using directive or an assembly reference?)

CS0246  The type or namespace name 'Context' could not be found (are you missing a using directive or an assembly reference?)

MyTunes.Droid\\MainActivity.cs

using System.Linq;
using Android.App;
using Android.OS;

namespace MyTunes
{
    [Activity(Label = "My Tunes", MainLauncher = true)]
    public class MainActivity : ListActivity
    {
        protected async override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            var data = await SongLoader.Load();

            ListAdapter = new ListAdapter<Song>() {
                DataSource = data.ToList(),
                TextProc = s => s.Name,
                DetailTextProc = s => s.Artist + " - " + s.Album
            };
        }
    }

    public class StreamLoader : IStreamLoader
    {
        private readonly Context context;

        public StreamLoader(Context context)
        {
            this.context = context;
        }
        public Stream GetStreamForFilename(string filename)
        {
            return context.Assets.Open(filename);
        }
    }
}

Portable\\IStreamLoader.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

namespace Portable
{
    public interface IStreamLoader
    {
        System.IO.Stream GetStreamForFilename(string filename);
    }
}

Answer 1

尝试这个 ：

using Android.Content;