Soy un nuevo Android, ahora quiero mostrar la imagen de una url. Estoy usando imageview en listview. Quiero agregar la lista de imágenes en cada fila del elemento de la lista. Usé SimpleAdapter pero la vista de imagen se muestra en blanco.

Aquí está la actividad principal:

package com.example.mysqltest;

    import java.util.ArrayList;
    import java.util.HashMap;
    import org.json.JSONArray;
    import org.json.JSONException;
    import org.json.JSONObject;
    import android.app.ListActivity;
    import android.app.ProgressDialog;
    import android.content.Intent;
    import android.os.AsyncTask;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.AdapterView;
    import android.widget.AdapterView.OnItemClickListener;
    import android.widget.ListAdapter;
    import android.widget.ListView;
    import android.widget.SimpleAdapter;

    public class ReadComments extends ListActivity {

        // Progress Dialog
        private ProgressDialog pDialog;

        // testing on Emulator:
        private static final String READ_COMMENTS_URL = "http://192.168.30.198/test/webservice/comments.php";


        // JSON IDS:
        private static final String TAG_SUCCESS = "success";
        private static final String TAG_TITLE = "title";
        private static final String TAG_POSTS = "posts";
        private static final String TAG_POST_ID = "post_id";
        private static final String TAG_USERNAME = "username";
        private static final String TAG_MESSAGE = "message";
        private static final String TAG_IMAGE = "image";


        // An array of all of our comments
        private JSONArray mComments = null;
        // manages all of our comments in a list.
        private ArrayList<HashMap<String, String>> mCommentList;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            // note that use read_comments.xml instead of our single_post.xml
            setContentView(R.layout.read_comments);
        }

        @Override
        protected void onResume() {
            // TODO Auto-generated method stub
            super.onResume();
            // loading the comments via AsyncTask
            new LoadComments().execute();
        }

        public void addComment(View v) {
            Intent i = new Intent(ReadComments.this, AddComment.class);
            startActivity(i);
        }

        /**
         * Retrieves recent post data from the server.
         */
        public void updateJSONdata() {
            mCommentList = new ArrayList<HashMap<String, String>>();

            JSONParser jParser = new JSONParser();      
            JSONObject json = jParser.getJSONFromUrl(READ_COMMENTS_URL);

            try {
                mComments = json.getJSONArray(TAG_POSTS);

                for (int i = 0; i < mComments.length(); i++) {
                    JSONObject c = mComments.getJSONObject(i);

                    // gets the content of each tag
                    String title = c.getString(TAG_TITLE);
                    String content = c.getString(TAG_MESSAGE);
                    String username = c.getString(TAG_USERNAME);
                    String image = c.getString(TAG_IMAGE);

                    // creating new HashMap
                    HashMap<String, String> map = new HashMap<String, String>();

                    map.put(TAG_TITLE, title);
                    map.put(TAG_MESSAGE, content);
                    map.put(TAG_USERNAME, username);
                    map.put(TAG_IMAGE, image);

                    // adding HashList to ArrayList
                    mCommentList.add(map);
                }

            } catch (JSONException e) {
                e.printStackTrace();
            }
        }

        /**
         * Inserts the parsed data into the listview.
         */
        private void updateList() { 
            ListAdapter adapter = new SimpleAdapter(this, mCommentList,
                    R.layout.single_post, new String[] { TAG_TITLE, TAG_MESSAGE,
                            TAG_USERNAME,TAG_IMAGE }, new int[] { R.id.title, R.id.message,
                            R.id.username, R.id.imageView1 });

            // I shouldn't have to comment on this one:
            setListAdapter(adapter);    

            ListView lv = getListView();    
            lv.setOnItemClickListener(new OnItemClickListener() {

                @Override
                public void onItemClick(AdapterView<?> parent, View view,
                        int position, long id) {}
            });
        }

        public class LoadComments extends AsyncTask<Void, Void, Boolean> {

            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                pDialog = new ProgressDialog(ReadComments.this);
                pDialog.setMessage("Loading Comments...");
                pDialog.setIndetermi,nate(false);
                pDialog.setCancelable(true);
                pDialog.show();
            }

            @Override
            protected Boolean doInBackground(Void... arg0) {
                updateJSONdata();
                return null;

            }

            @Override
            protected void onPostExecute(Boolean result) {
                super.onPostExecute(result);
                pDialog.dismiss();
                updateList();
            }
        }
    }