A hard disk cache for storing Bitmaps in Xamarin.Android

BitmapDiskCache.cs

using System.Threading.Tasks;
using Android.Content;
using Android.Graphics;
using Java.IO;

namespace Android.Util.Graphics
{
    public static class BitmapDiskCache
    {
        private const string Extension = @".fil";
        public static File CacheDir { get; set; }

        public static async void Add(string id, Bitmap bitmap)
        {
            byte[] data = await BitmapLoader.EncodeBitmap(bitmap);

            File file = new File(CacheDir, id + Extension);
            FileOutputStream os = new FileOutputStream(file);
            try
            {
                await os.WriteAsync(data);
            }
            finally
            {
                os.Flush();
                os.Close();
            }
        }

        public static async Task<Bitmap> Get(string id)
        {
            File file = new File(CacheDir, id + Extension);

            if (!file.Exists())
            {
                // Data doesn't exist
                return null;
            }

            byte[] data = new byte[file.Length()];
            FileInputStream inputStream = new FileInputStream(file);
            try
            {
                await inputStream.ReadAsync(data);
            }
            finally
            {
                inputStream.Close();
            }

            return await BitmapLoader.DecodeBitmap(data);
        }
    }
}