Help Understanding Java AsyncTask Code

Hello,

Creating Java project in Android Studio 0.8.14.  Learning to use AsyncTask to send HTTPRequest with JSON parameters and response.  

The following code works great.  It sends the parameters to URL and properly evaluates Login Failure or Login Success.  Problem is that I don't understand how to use that response in the rest of my program.

Specifically, how do I use the returned values in lines 98 and 101 to change the tvwStatus TextView in my Layout?

package com.android.json.login;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.AsyncTask;
import android.text.Layout;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

import org.apache.http.message.BasicNameValuePair;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;


public class Login extends Activity implements OnClickListener {

    private EditText editUsername, editPassword;
    private TextView tvwStatus;
    private Button btnLogin;

    JSONParser jsonParser = new JSONParser();

    private static final String LOGIN_URL = "http://m.binghamtonyoga.com/login.php";
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_MESSAGE = "message";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        // *** Setup GUI Objects ***
        editUsername = (EditText)findViewById(R.id.editUsername);
        editPassword = (EditText)findViewById(R.id.editPassword);
        tvwStatus = (TextView)findViewById(R.id.tvwStatus);
        btnLogin = (Button)findViewById(R.id.btnLogin);

        // *** Register OnClick Listener ***
        btnLogin.setOnClickListener(this);
    }

    public void onClick(View v) {
        // *** Which Button was Clicked? ***
        switch (v.getId()) {
            case R.id.btnLogin:
                new AttemptLogin().execute();
                break;
            default:
                break;
        }
    }

    // ***************************************************************************
    // Async Task to Attempt Login
    // ***************************************************************************
    class AttemptLogin extends AsyncTask<String,Void,String> {

        boolean failure = false;

        @Override
        protected String doInBackground(String... args) {

            // Check for success tag
            int success;
            String username = editUsername.getText().toString();
            String password = editPassword.getText().toString();
            try {
                // *** Build Parameters ***
                List params = new ArrayList();
                params.add(new BasicNameValuePair("txtUsername", username));
                params.add(new BasicNameValuePair("txtPassword", password));

                // *** Make HTTP Request to Login with Parameters ***
                Log.d("***HTTPRequest URL:", LOGIN_URL);
                Log.d("***HTTPRequest Type:", "POST");
                Log.d("***HTTPRequest Param(0):", params.get(0).toString());
                Log.d("***HTTPRequest Param(1):", params.get(1).toString());
                JSONObject json = jsonParser.makeHttpRequest(LOGIN_URL, "POST", params);
                Log.d("***HTTPRequest Response:", json.toString());

                // json success tag
                success = json.getInt(TAG_SUCCESS);
                if (success == 1) {
                    Log.d("***LOGIN SUCCESS***", json.toString());
                    Intent i = new Intent(Login.this, Layout.class);
                    finish();
                    startActivity(i);
                    return json.getString(TAG_MESSAGE);
                }else{
                    Log.d("***LOGIN FAILURE***", json.getString(TAG_MESSAGE));
                    return json.getString(TAG_MESSAGE);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
            return null;
        }

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_login, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

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Thank you!

Jason