Wait for AsyncTask to complete its onPostExecute() while also keep the UI thread open for a ProgressDialog

Question

I have been reading a good amount about AsyncTasks but I can't figure something out. I have an AsyncTask that I start that is used for an HttpURLConnection for a request from my database. The database work is done in doInBackground() and I have a ProgressDialog that runs on the UI thread that just shows that it is loading. Once the doInBackground() is complete though, my code continues even though I have some things in the onPostExecute() that need to happen before the code can continue.

Is there a way to keep the AsyncTask asynchronous so I can run the ProgressDialog and do the database work in doInBackgroun() at the same time and also have it wait to continue until onPostExecute() has been called?

To clarify:

I cannot just call a function in the onPostExecute() call. At launch an AlertDialog is opened in order for the user to input their username and password so they can login. When they hit login, the AsyncTask is run. I need the AlertDialog to know when the onPostExecute() is complete as well in order to close it. Otherwise I'll be stuck with it.

Here is the code for the AlertDialog in the beginning:

AlertDialog.Builder alert = new AlertDialog.Builder(context);
alert.setCancelable(false);
final EditText usernameInput = new EditText(context);
usernameInput.setHint("Username");
final EditText passwordInput = new EditText(context);
passwordInput.setHint("Password");
passwordInput.setTransformationMethod(PasswordTransformationMethod.getInstance());
LinearLayout layout = new LinearLayout(context);
layout.setOrientation(LinearLayout.VERTICAL);
layout.addView(usernameInput);
layout.addView(passwordInput);
alert.setView(layout);
alert.setTitle("Login");
alert.setPositiveButton("Login", new DialogInterface.OnClickListener()
{
    @Override
    public void onClick(DialogInterface dialog, int which)
    {
        String username = usernameInput.getText().toString();
        String password = passwordInput.getText().toString();
        if (username != "" && password != "")
        {
            Database database = new Database(currActivity);
            database.Login(username, password);
            if (database.IsLoggedIn())
            {
                SharedPreferences prefs = currActivity.getSharedPreferences("Preferences", currActivity.MODE_PRIVATE);
                prefs.edit().putBoolean("Logged In", true).commit();
                dialog.cancel();
            }
            else ShowLoginAlert(context);
        }
    }
});
alert.show();

Here is my code for the login:

public void Login(String username, String password)
{
    try
    {
        new AsyncLogin().execute(username, password).get();
    }
    catch (InterruptedException e)
    {
        e.printStackTrace();
    }
    catch (ExecutionException e1)
    {
        e1.printStackTrace();
    }
}

private class AsyncLogin extends AsyncTask<String, String, String>
{
    private static final int READ_TIMEOUT = 1000000;
    private static final int CONNECTION_TIMEOUT = 1000000;
    private URL url = null;
    private HttpURLConnection conn = null;
    ProgressDialog loading = new ProgressDialog(currActivity);

    @Override
    protected void onPreExecute()
    {
        super.onPreExecute();
        loading.setMessage("\tLoading...");
        loading.setCancelable(false);
        loading.show();
    }

    @Override
    protected String doInBackground(String... params)
    {
        try
        {
            url = new URL("http://mysite/myscript.php");
        }
        catch (MalformedURLException e)
        {
            e.printStackTrace();
            return "Malformed URL Exception.";
        }

        try
        {
            conn = (HttpURLConnection) url.openConnection();
            conn.setReadTimeout(READ_TIMEOUT);
            conn.setConnectTimeout(CONNECTION_TIMEOUT);
            conn.setRequestMethod("POST");
            conn.setDoInput(true);
            conn.setDoOutput(true);

            Uri.Builder builder = new Uri.Builder()
                    .appendQueryParameter("username", params[0])
                    .appendQueryParameter("password", params[1]);

            String query = builder.build().getEncodedQuery();

            OutputStream os = conn.getOutputStream();
            BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os, "UTF-8"));
            writer.write(query);
            writer.flush();
            writer.close();
            conn.connect();
        }
        catch (IOException e1)
        {
            e1.printStackTrace();
            return "Connection Exception.";
        }

        try
        {
            int responseCode = conn.getResponseCode();
            if (responseCode == HttpURLConnection.HTTP_OK)
            {
                InputStream input = conn.getInputStream();
                BufferedReader reader = new BufferedReader(new InputStreamReader(input));

                StringBuilder result = new StringBuilder();
                String line;

                while ((line = reader.readLine()) != null)
                {
                    result.append(line);
                }

                return result.toString();
            }
            else return "Unsuccessful data retrieval.";
        }
        catch (IOException e2)
        {
            e2.printStackTrace();
            return "Response Exception.";
        }
        finally
        {
            conn.disconnect();
        }
    }

    @Override
    protected void onPostExecute(String result)
    {
        super.onPostExecute(result);

        loading.dismiss();

        if (result.equalsIgnoreCase("true"))
        {
            // Successfully logged in
            SetIsLoggedIn(true);
            Toast.makeText(currActivity, "Successfully logged in.", Toast.LENGTH_LONG).show();
        }
        else
        {
            // Incorrect credentials
            SetIsLoggedIn(false);
            Toast.makeText(currActivity, "Incorrect credentials.", Toast.LENGTH_LONG).show();
        }
    }
}

Answer 1

you can do this in following way:

class main extends Activity {

class Something extends AsyncTask<String, Integer, String> {

    protected void onPreExecute() {
     //  showProgressDialog
    }

    protected String doInBackground(String... params) {
        // Do your heavy stuff...
        return null;
    }

    protected void onPostExecute(String result) {
        // close your progress dialog and than call method which has
        // code you are wishing to execute after AsyncTask.
    }
}

}

Answer 2

i think what you want is not very difficult, you can use following code :

class main extends MainActivity {

class SampleAsyncTask extends AsyncTask<String, Integer, String> {

    protected void onPreExecute() {
     //  ProgressDialog
    }

    protected String doInBackground(String... params) {
        // Do your database code...
        return null;
    }

    protected void onPostExecute(String result) {
        // close progress dialog 
        // code you are wishing to execute after AsyncTask.
    }
}
}

Answer 3

If I understand it correctly, you have two dialogs(progress and alert) and you want to dismiss one of them after you get login response and keep the other one till database work is done.

If yes, I think you would need two async tasks, one for login and one for database work. Dismiss one of the dialogs in the postExecute(0 of first async task and Call the database async task from the postExecute of the first async task and then dismiss the second on the completion of the second async task.

Answer 4

This post gives an example of using an interface in order to have a function called when the onPostExecute() is called so that it was possible to access the AlertDialog from where I needed to access it.