How to get data by json on xamarin android - json

Question

public async override void OnActivityCreated (Bundle savedInstanceState)
{
base.OnActivityCreated (savedInstanceState);
lst = View.FindViewById<ListView> (Resource.Id.lstHome);
var result = await json.GetStringbyJson ("https://api-v2.soundcloud.com/explore/Popular+Music?tag=out-of-experiment&limit=20&linked_partitioning=1");
if (result != null)
{
var items = Newtonsoft.Json.JsonConvert.DeserializeObject<TrackModel.RootObject> (result);
lst.Adapter = new TrackAdapter(Activity, items.tracks);
}
}
public class TrackAdapter:BaseAdapter
{
LayoutInflater _inflater;
List<TrackModel.Track> _tracks;
public TrackAdapter(Context context, List<TrackModel.Track> tracks)
{
_inflater=LayoutInflater.FromContext(context);
_tracks=tracks;
}
public override TrackModel.Track this[int index]
{
get{ return _tracks [index]; }
}
public override int Count{
get{ return _tracks.Count; }
}
public override long GetItemId(int position)
{
return position;
}
public override View GetView(int position, View convertView,ViewGroup parent)
{
View view = convertView ?? _inflater.Inflate (Resource.Layout.ExploreFragment, parent, false);
var track = _tracks [position];
var viewHolder = view.Tag as TrackViewHolder;
if (viewHolder == null) {
viewHolder.Title = view.FindViewById<TextView> (Resource.Id.textviewItems);
viewHolder.SubTitle = view.FindViewById<TextView> (Resource.Id.textviewSubItem);
viewHolder.Image = view.FindViewById<ImageView> (Resource.Id.image);
view.Tag = viewHolder;
}
viewHolder.Title.Text = track.title;
viewHolder.SubTitle.Text = track.track_type;
Android.Net.Uri uri = Android.Net.Uri.Parse (track.artwork_url);
viewHolder.Image.SetImageURI(uri);
return view;
}
}
public class TrackViewHolder:Java.Lang.Object
{
public TextView Title{ get; set;}
public TextView SubTitle{get;set;}
public ImageView Image{ get; set;}
}
public override TrackModel.Track this[int index]. It get a error is makred as an overdie but no suitable indexer found to overide.
I want to take data from json up listview on xamarin android.
If it is unviersal app then it easy to use.

Answer 1

The way you want to set the adapter for your listview will not work that way.
Setting the adapter property of the listview inside the foreach loop is totally wrong. The same applies to your textviews.
You need to implement a custom adapter that loads a layout for each of your track list item. Your custom adapter could look like the following example I've written out of my mind with out further testing. But it implements the required methods a custom adapter needs to implement.
The important part is the GetView method that returns your track layout every time the listview ask for a new item to represent. To keep the app memory down it uses the ViewHolder pattern, which isn't required if you want to use the RecycleView.
public class TrackAdapter : BaseAdapter<Tracks>
{
LayoutInflater _inflater;
List<Tracks> _tracks;
public TrackAdapter(Context context, List<Tracks) tracks)
{
_inflater = LayoutInflater.FromContext(context);
_tracks = tracks;
}
public override Tracks this [int index]
{
get { return _tracks[index]; }
}
public override int Count
{
get { return _tracks.Count; }
}
public override long GetItemId(int position)
{
return position;
}
public override View GetView(int position, View convertView, ViewGroup parent)
{
View view = convertView ?? _inflater.Inflate(Resource.Layout.TrackListItem, parent, false);
var track = _tracks[position];
var viewHolder = view.Tag as TrackViewHolder;
if (viewHolder == null)
{
viewHolder = new TrackViewHolder();
viewHolder.Title = view.FindViewById<TextView>(Resource.Id.textviewItems);
viewHolder.Subtitle = view.FindViewById<TextView>(Resource.Id.textviewSubItems);
viewHolder.Image = view.FindViewById<ImageView>(Resource.Id.image);
view.Tag = viewHolder;
}
viewHolder.Title.Text = track.title;
viewHolder.SubTitle.Text = track.track_type;
viewHolder.Image.SetImageURI(Uri(track.artwork_url));
return view;
}
class TrackViewHolder : Java.Lang.Object
{
public TextView Title { get; set; }
public TextView SubTitle { get; set; }
public ImageView Image { get; set; }
}
}
The layout will contain your title, subtitle and image and could easily build with a normal layout file.
In your fragment you then create a new instance for TrackAdapter pass the context and the list of tracks you want to be shown in the listview.
public override void OnActivityCreated (Bundle savedInstanceState)
{
base.OnActivityCreated (savedInstanceState);
lst = View.FindViewById<ListView> (Resource.Id.lstHome);
var result = json.GetStringbyJson ("https://api-v2.soundcloud.com/explore/Popular+Music?tag=out-of-experiment&limit=20&linked_partitioning=1");
if (result != null)
{
var items = JsonConvert.DeserializeObject<TrackModel.RootObject> (result);
lst.Adapter = new TrackAdapter(Activity, items.tracks);
}
}