Question

I have a parsed list view. The number of elements are not fixed.
When i click an item of the listview, it show the corresponding file on the other activity as i need.
so far this all is working as i want.
Now i want to show thumbnail on each List item. the file that opens on each click is a “.png” file, and i want to show that png as a thumbnail too on the list (each item having its respective thumbnail)
How can i do this?? i am new to android so plz give me code sample for help.
i have done alot searching and read about lazy loading kind of stuff but its very complicated for me.
thanks in advance for help!!

Answer 1

You need to extend the adapter for the listview then in the getView() method of the adapter specify a custom layout.

private class MyAdapter extends ArrayAdapter</*params*/> {

    private ArrayList</*params*/> items;

    //you will a reference to a context in getView()
    private Context ctx;

    public MyAdapter(Context context, int resourceId, ArrayList</*params*/> items) {
            super(context, resourceId, items);
            this.items = items;
            this.ctx = context;
    }

//here is where you can create a custom view for each list item
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

            View v = convertView;
            if (v == null) {
                LayoutInflater vi = (LayoutInflater)ctx.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                v = vi.inflate(R.layout.my_custom_view, null);

               //Your custom view will contain an ImageView 
               //which you can assign the thumbnail to.
               ImageView image = (ImageView)convertView.findViewById(R.id.my_custom_view_thumbnail);

               //set the thumbnail from a drawable resource
               new GetImage("http://www.example.com").execute(image);

            }

            return v;
    }
}

For downloading an image

public class GetImage extends AsyncTask<ImageView, Void, ImageView> {

    String url = null;
    Bitmap thumbnail = null;
    public GetImage(String url){
        this.url = url;
    }
    @Override
    protected void onPreExecute() {

    }

    @Override
    protected ImageView doInBackground(ImageView... params) {

        try {
            thumbnail = BitmapFactory.decodeStream((InputStream) new URL(url).getContent());

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return params[0];

    }

    @Override
    public void onPostExecute(ImageView result) {
        result.setImageBitmap(thumbnail);

    }
}