Type Mismatch: Cannot Convert From Asynctask

Update based on @Tom solution: SongsManager.java public class SongsManager extends AsyncTask>> { publi

Solution 1:

The value returned from SongsManager.execute() is not the results of the computation; it's the AsyncTask itself. To publish your results, write a method in SongsManager:

voidonPostExecute(ArrayList<HashMap<String,String>> result) {
    songsList = result; // or something similar// then update the UI to reflect the results
}

In this method, songsList is the variable to which you are now trying to assign the return value from new SongsManager.execute(). If this variable is not visible to the SongsManager class (e.g., it's not a nested class of your main class), then you'll have to arrange for a call-back:

publicclassSongsManagerextendsAsyncTask<Void, Void, List<Map<String,String>>
{
    publicinterfaceSongsMasterCallback {
        voidshowSongList(List<Map<String, String>> result);
    }

    privateSongsMasterCallback mCallback;

    publicSongsMaster(SongsMasterCallback callback) {
        mCallback = callback;
    }

    @OverrideprotectedList<Map<String, String>>  doInBackground(Void... params) {
        // as before
    }

    @OverrideprotectedvoidonPostExecute(List<Map<String, String>> result) {
        mCallback.showSongList(result);
    }
}

Then declare your activity to implement SongsManager.SongsManagerCallback and add is method:

voidshowSongList(List<Map<String, String>> songList) {
    this.songList = songList;
    // then do something with the list here
}

Solution 2:

That's because you do not get the ArrayList<HashMap<String, String>> returned when you create / execute the AsyncTask. You get it back on the onPostExecute(). You should create/execute the task like this

SongsManagersongsList=newSongsManager().execute();

and then have a onPostExecute in your AsyncTask like this

protectedvoidonPostExecute(ArrayList<HashMap<String, String>> result) 
{
  // do stuff with the ArrayList<HashMap<String, String>> result parameter.
}