How use ProgressDialog and Async Task get Method simultaneously

Question

I have generic async task class which fetches response from server . And i receive those response by using get method . Now i knw that UI thread is block when i use get method , bcoz of which my progress Dialog doesnt showup on time .

Now can someone tell me alternative to do this ?? (In every case i need to send back the response to the activity which has made the call of execute so opening new activity wouldn't help me )

Code : AsyncTask Class

 public class GetDataFromNetwork extends AsyncTask<Void,String,Object> {

protected void onPreExecute() {
    super.onPreExecute();
    progressDialog.show();
} 


 protected Object doInBackground(Void... params) {
    Object result = null;
    try {
        SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER10);
        new MarshalBase64().register(envelope);
        envelope.dotNet = true;
        envelope.setOutputSoapObject(request);
        AndroidHttpTransport androidHttpTransport = new AndroidHttpTransport(ipAddress + webService);
        System.setProperty("http.keepAlive", "true");
        try {
            androidHttpTransport.call(nameSpace + methodName, envelope);
        } catch (Exception e) {

            e.printStackTrace();
            publishProgress(e.getMessage());
        }
        androidHttpTransport.debug = true;
        System.out.println("response: " + androidHttpTransport.requestDump);
        result = envelope.getResponse();
        if(result!=null){
            System.out.println("GetDataFromNetwork.doInBackground() result expection---------"+result);
        }
    } catch (Exception e) {
        System.out.println("GetDataFromNetwork.doInBackground()-------- Errors");
        e.printStackTrace();

    }

    return result;
}

protected void onPostExecute(Object result) {
    super.onPostExecute(result);
    progressDialog.dismiss();
}

Code : Activity

GetDataFromNetwork request = new GetDataFromNetwork(
                                        this,
                                        ProgressDialog.STYLE_SPINNER,
                                        getResources().getText(R.string.autenticate).toString());
response= (SoapObject)request.execute().get();

Answer 1

I'm doing stuff like this all the time in my apps and the easiest way I found was to create "Callback" interface and pass it as a parameter to my "AsyncTask"s. You do your "doInBackground()" processing and when it's finished you call the "Callback" instance from onPostExecute passing the "result" object as parameter.

Below is a very simplified version of it.

Example of Callback interface:

package example.app;

public interface Callback {

        void run(Object result);
}

Example of AsyncTask using the Callback interface above:

public class GetDataFromNetwork extends AsyncTask<Void,String,Object> {
  Callback callback;
  public GetDataFromNetwork(Callback callback){
     this.callback = callback;
  }

   protected void onPreExecute() {
      super.onPreExecute();
      progressDialog.show();
  } 


   protected Object doInBackground(Void... params) {
      Object result = null;
      // do your stuff here
      return result;
  }

  protected void onPostExecute(Object result) {
     callback.run(result);
     progressDialog.dismiss();
  }

}

Example of how to use the classes above in your app:

class Example {
   public onCreate(Bundle savedInstanceState){
      //initialize

      GetDataFromNetwork request = new GetDataFromNetwork(new Callback(){
                     public void run(Object result){
                             //do something here with the result
       }});
       request.execute();      
   }
}

Answer 2

Like yorkw says, The problem is that you make the UI thread wait for the response with this code:

response= (SoapObject)request.execute().get();

As the documentation for AsyncTask.get() says:

Waits if necessary for the computation to complete, and then retrieves its result.

Since the UI thread waits for the response, it can't show a progress dialog. The solution is to move the code that handles the response to the onPostExecute() method:

protected void onPostExecute(Object result) {
    super.onPostExecute(result);

    // Now we have the response, dismiss the dialog and handle the response
    progressDialog.dismiss();
    response = (SoapObject) result;
}

This method will be invoked after you have the response. Meanwhile, the UI thread can take care of showing a progress dialog.