Am using Async Task in my application to get response from web service using restful web service. My code
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_json_page);
_mContext = this;
new JSONParserTask().execute();
}
asynctask class
private class JSONParserTask extends AsyncTask<Void, Void, ListAdapter >{
ProgressDialog dialog;
@Override
protected void onPreExecute() {
// dialog = new ProgressDialog(_mContext);
// dialog.setMessage("Loading...");
// dialog.show();
super.onPreExecute();
}
@Override
protected ListAdapter doInBackground(Void... arg0) {
ListAdapter adapter = null;
itemsList = new ArrayList<HashMap<String, String>>();
jParser = new JSONParser();
JSONObject json = jParser.getJSONFromUrl(Constants.JsonURL);
if(json == null){
Log.v(TAG, "----------- null");
return null;
}
try {
// Getting Array of Items
items = json.getJSONArray(TAG_ITEMS);
// looping through All items
for(int i = 0; i < items.length(); i++) {
JSONObject itemsObj = items.getJSONObject(i);
JSONObject products = null;
products = itemsObj.getJSONObject(TAG_PRODUCT);
Log.d(TAG,"product array "+products.toString());
JSONArray images = products.getJSONArray(TAG_IMAGES);
JSONObject imagesObj = images.getJSONObject(0);
Log.d(TAG, "......."+ imagesObj.getString(TAG_LINK));
String imageUrl = imagesObj.getString(TAG_LINK);
// Storing each json item in variable
String kind = itemsObj.getString(TAG_KIND);
String id = itemsObj.getString(TAG_KID);
String selfLink = itemsObj.getString(TAG_SELFLINK);
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_KIND, kind);
map.put(TAG_KID, id);
map.put(TAG_SELFLINK, selfLink);
// adding HashList to ArrayList
itemsList.add(map);
}
/**
* Updating parsed JSON data into ListView
* */
adapter = new SimpleAdapter(_mContext, itemsList,
R.layout.list_item_row,
new String[] { TAG_KIND, TAG_SELFLINK }, new int[] {
R.id.name, R.id.mobile });
} catch(JSONException e){
e.printStackTrace();
}
return adapter;
}
@Override
protected void onPostExecute(ListAdapter adapter) {
lv.setAdapter(adapter);
// Launching new screen on Selecting Single ListItem
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// some action
}
});
//dialog.dismiss();
}
}
with this code every thing working fine without using progress dialog. If u found, the code related to progress dialog is commented in above class. If i uncomment progress dialog code, am not getting any response from server. I have tried with debugging also but never get any idea to remove this error. Can some one tell what wrong am doing here.
ok the reason for that is you are updating you are adapter in your doInBackground()
method
adapter = new SimpleAdapter(_mContext, itemsList,
R.layout.list_item_row,
new String[] { TAG_KIND, TAG_SELFLINK }, new int[] {
R.id.name, R.id.mobile });
This code is related to the MAIN THREAD and shouldn't be called here in the background thread, remove it from here, and add it to the onPostExecute()
, just pass an array list from the Background thread and do other UI related stuff in the onPostExecute()
Try this
ProgressDialog mProgressDialog;
@Override
protected void onPreExecute() {
mProgressDialog= ProgressDialog.show(getApplicationContext(),"", getString(R.string.dialog_wait_message));
super.onPreExecute();
}
protected void onPostExecute(Void result) {
if(mProgressDialog!=null){
mProgressDialog.dismiss();
}
}
Try this one, rather
ProgressDialog mProgressDialog;
@Override
protected void onPreExecute() {
mProgressDialog= ProgressDialog.show(getApplicationContext(),"", getString(R.string.dialog_wait_message));
super.onPreExecute();
}
@Override
protected ListAdapter doInBackground(Void... arg0){
//do your stuff here
}
@Override
protected void onPostExecute(Void result) {
if(mProgressDialog!=null && mProgressDialog.isShowing()){
mProgressDialog.dismiss();
}
}
Try this
@Override
protected void onPreExecute() {
pd=new ProgressDialog(m_context);
pd.setTitle("Authenticating");
pd.show();
}
@Override
protected Void doInBackground(Void... args) {
//your stuff
}
@Override
protected void onPostExecute(Void result) {
pd.dismiss();
}
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