How to return value from async task in android

Question

I created an async task to call my server to get data from DB.
I need to process the result returned from http server call.
From my activity i calling the async task in many places. so i cant use member variable to access the result. is there any way to do?

public Result CallServer(String params)
{

    try
    {
    new MainAynscTask().execute(params);
    }
    catch(Exception ex)
    {
        ex.printStackTrace();
    }
    return aResultM;//Need to get back the result

}  

    private class MainAynscTask extends AsyncTask<String, Void, Result> {


    @Override
    protected Result doInBackground(String... ParamsP) {    
        //calling server codes
        return aResultL;
    }       
    @Override
       protected void onPostExecute(Result result) {
          super.onPostExecute(result);
          //how i will pass this result where i called this task?
       }

Answer 1

Try to call the get() method of AsyncTask after you call the execute() method. This works for me

http://developer.android.com/reference/android/os/AsyncTask.html#get()

public Result CallServer(String params)
{
   try
   {
       MainAynscTask task = new MainAynscTask();
       task.execute(params);
       Result aResultM = task.get();  //Add this
   }
   catch(Exception ex)
   {
       ex.printStackTrace();
   }
   return aResultM;//Need to get back the result

} 
...
...

Answer 2

There are two ways i can suggest -

1. onPostExecute(Result) in AsyncTask. See http://developer.android.com/reference/android/os/AsyncTask.html#onPostExecute(Result)

2. Send a broadcast with the result as an extra.

AsyncTask is an asynchronous task so it does NOT make sense to return the result to the caller. Rather handle the result in onPostExecute() like setting the value to TextView etc. Or send a broadcast so that some other listener can handle the result.