[mono-android] creating adapter from resource

[Jonathan Pryor]

On Mar 27, 2011, at 9:28 AM, John Murray wrote:
> So can anyone tell me why the first of these doesn’t work but the second does
...
>  
> Simple approach which doesn’t work
> airfadapter =new ArrayAdapter(this, Resource.Layout.list_item, Resource.Array.GBairfarr1);
>               depfield.Adapter = airfadapter;

The corresponding documentation:

	http://developer.android.com/reference/android/widget/ArrayAdapter.html#ArrayAdapter(android.content.Context, int, int)

Thus, for the ArrayAdapter(Context context, int resource, int textViewResourceId), the textViewResourceId is:

	"The id of the TextView within the layout resource to be populated."

In other words, it's _not_ the array to use to populate the adapter, it's a resource id _within_ `resource` that contains the TextView to fill.

So it doesn't work because it doesn't do what you thought it did. :-)
 
> But this works
> Android.Widget.ArrayAdapter<string> adapter = new ArrayAdapter<string>(this,Resource.Id.wtv2);           
>             List<string> arr3 = new List<string>();
>             arr3 = (from s in Resources.GetStringArray(Resource.Array.airfarr1) select s).ToList();
>             foreach (var s in arr3)
>              {
>                  if (s.Substring(0,2)=="EG")
>                  {
>                 adapter.Add(s);
>                  }
>              }
> depfield.Adapter = adapter;
>  
> //the above foreach loop was only inserted t filter the list and has no significance in this
> //other than it serves as a means for getting a list into an android adapter
>          
>  
> Ps is there some easy way to convert a System.collection.list to an android.widget.arrayadapter

There is an ArrayAdapter<T>(Context, int, IList<T>) constructor and an ArrayAdapter<T>(Context, int, T[]) constructor:

	http://docs.mono-android.net/index.aspx?link=T%3aAndroid.Widget.ArrayAdapter`1%2f*

Thus, you should be able to do:

	var adapter = new ArrayAdapter<string>(this, Resource.Id.wtv2, Resources.GetStringArray(Resource.Array.airfarr1));

or:

	var adapter = new ArrayAdapter<string>(this, Resource.Id.wtv2, 
		Resources.GetStringArray(Resource.Array.airfarr1).Where(s => s.StartsWith ("EG")).ToList());

 - Jon