This example code was used by me to load all the events from an SQL database. Until the app gets the data from the server, a progress dialog is displayed to the user.
class LoadAllEvents extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(getActivity());
pDialog.setMessage("Just a moment...");
pDialog.setIndeterminate(true);
pDialog.setCancelable(true);
pDialog.show();
}
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_events,
"GET", params);
try {
// Checking for SUCCESS TAG
int success = json.getInt(CONNECTION_STATUS);
if (success == 1) {
// products found
// Getting Array of Products
Events = json.getJSONArray(TABLE_EVENT);
// looping through All Contacts
for (int i = 0; i < Events.length(); i++) {
JSONObject evt = Events.getJSONObject(i);
// Storing each json item in variable
id = evt.getString(pid);
group = evt.getString(COL_GROUP);
name = evt.getString(COL_NAME);
desc = evt.getString(COL_DESC);
date = evt.getString(COL_DATE);
time = evt.getString(COL_TIME);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(pid, id);
map.put(COL_GROUP, group);
map.put(COL_NAME, name);
map.put(COL_DESC, desc);
map.put(COL_DATE, date);
map.put(COL_TIME, time);
// adding HashList to ArrayList
eventsList.add(map);
}
} else {
// Options are not available or server is down.
// Dismiss the loading dialog and display an alert
// onPostExecute
pDialog.dismiss();
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
getActivity().runOnUiThread(new Runnable() {
public void run() {
ListAdapter adapter = new SimpleAdapter(getActivity(),
eventsList, R.layout.list_item, new String[] {
pid, COL_GROUP, COL_NAME, COL_DATE, COL_TIME },
new int[] { R.id.pid, R.id.group, R.id.name, R.id.header,
R.id.title2 });
setListAdapter(adapter);
}
});
}
hope this helps.