Parameters of AsyncTask in Android

Issue

I'm trying to understand AsyncTask in Android. I can't understand how do we pass parameters. In this code :

 protected class AsyncLogin extends AsyncTask<String, JSONObject, Boolean> {
        String userName = null;

        @Override
        protected Boolean doInBackground(String... params)
        {
            RestAPI api = new RestAPI();
            boolean userAuth = false;
            try
            {
                JSONObject jsonObj = api.UserAuthentication(params[0], params[1]);
                JSONParser parser = new JSONParser();
                userAuth = parser.parseUserAuth(jsonObj);
                userName = params[0];

            }
            catch (Exception e)
            {
                Log.d("AsyncLogin", e.getMessage());
            }

            return  userAuth;
        }

        @Override
        protected void onPreExecute()
        {
            super.onPreExecute();
            Toast.makeText(context, "Please wait...", Toast.LENGTH_SHORT).show();
        }

        @Override
        protected  void onPostExecute(Boolean result)
        {
            if(result) {
                Intent i = new Intent(LoginActivity.this, UserDetailsActivity.class);
                i.putExtra("username", userName);
                startActivity(i);
            }
            else
            {
                Toast.makeText(context, "Not valid username/password", Toast.LENGTH_SHORT).show();
            }
        }
    }

I can't understand why do we use <String, JSONObject, Boolean> in

protected class AsyncLogin extends AsyncTask<String, JSONObject, Boolean>

What do String, JSONObject and Boolean refer to? Can you explain it to me? Thanks.

Solution

AsyncTask (Type1, Type2, Type3) uses argument types:

• Type1 is the type of argument you pass when you call execute (received in doInBackground)
• Type2 is the type of the argument you pass to onProgressUpdate when you call publishProgress.
• Type3 is the type of argument you pass to onPostExecute, which is what you return from doInBackground.

Answered By - Gordak