Question

I have a problem with an Asynctask, I can’t get the return values of the doInBackground method in the OnPostExecute, can you help me?

I setted the return value of the Asynctask as an Integer, and the value that I’m returning is an int, so why does the app stop on the return of the doInBackground?

If you can explain to me how the Asynctask works I will really appreciate it.

Thank you very much!!

public class LoginActivity extends Activity 
{
ProgressDialog pDialog;
JSONParser jParser = new JSONParser();

Button btnLogin;
Button btnLinkToRegister;
EditText inputEmail;
EditText inputPassword;
TextView loginErrorMsg;

JSONArray user = null;
ArrayList<HashMap<String, String>> userList;


private static String loginURL = "htttp://example.com/query.php";

private static String KEY_SUCCESS = "success";
private static String KEY_EMAIL = "email";
private static String KEY_PASSWORD = "password";

@Override
public void onCreate(Bundle savedInstanceState) 
{    
    super.onCreate(savedInstanceState);
    setContentView(R.layout.login);

    userList = new ArrayList<HashMap<String, String>>();

    inputEmail = (EditText) findViewById(R.id.loginEmail);
    inputPassword = (EditText) findViewById(R.id.loginPassword);
    btnLogin = (Button) findViewById(R.id.btnLogin);
    btnLinkToRegister = (Button) findViewById(R.id.btnLinkToRegisterScreen);

    btnLogin.setOnClickListener(new View.OnClickListener() 
    {   
        @Override
        public void onClick(View v) 
        {
            new CheckUser().execute();          
        }
    });


}

/**
 * Background Async Task to Load all product by making HTTP Request
 * */

class CheckUser extends AsyncTask<String, String, Integer> 
{
    /**
     * Before starting background thread Show Progress Dialog
     * */
    @Override
    protected void onPreExecute() 
    {
        super.onPreExecute();
        pDialog = new ProgressDialog(LoginActivity.this);
        pDialog.setMessage("Verifica dati inseriti...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(false);
        pDialog.show();
    }

    protected Integer doInBackground(String... args)
    {
        int valoreOnPostExecute = 0;

        String emailInserted = inputEmail.getText().toString();
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        params.add(new BasicNameValuePair("email", emailInserted));
        // getting JSON string from URL
        JSONObject json = null;

        json = jParser.getJSONFromUrl(loginURL, params);

        // Check your log cat for JSON response
        Log.d("All Users: ", json.toString());

        try 
        {
            // Checking for SUCCESS TAG
            int success = json.getInt(KEY_SUCCESS);

            if (success == 1) 
            {
                // users found
                // Getting Array of users
                user = json.getJSONArray("utenti");

                // looping through All users
                for (int i = 0; i < user.length(); i++) 
                {
                    JSONObject c = user.getJSONObject(i);

                    // Storing each json item in variable
                    String email = c.getString(KEY_EMAIL);
                    String password = c.getString(KEY_PASSWORD);

                    // creating new HashMap
                    HashMap<String, String> map = new HashMap<String, String>();

                    // adding each child node to HashMap key => value
                    map.put(KEY_EMAIL, email);
                    map.put(KEY_PASSWORD, password);

                    // adding HashList to ArrayList
                    userList.add(map);
                }

//                    Intent intent = new Intent(LoginActivity.this,GenereMusicale.class);
//                    startActivity(intent);
                    valoreOnPostExecute = success;
                } 
//                else 
//                {
//                  Log.d("success != 1", json.toString());
//                  //Toast.makeText(LoginActivity.this, "Username/password non corretti", Toast.LENGTH_SHORT).show();
//                }
        }
        catch (JSONException e) 
        {
            e.printStackTrace();
            Log.d("User ARRAY", "user array: "+user);
        }

        return valoreOnPostExecute;
    }

    /**
     * After completing background task Dismiss the progress dialog
     * **/
    protected void onPostExecute(int valoreOnPostExecute) 
    {
        // dismiss the dialog after getting all products
        pDialog.dismiss();
        // updating UI from Background Thread

        if(valoreOnPostExecute == 1)
        {
            Intent intent = new Intent(LoginActivity.this,GenereMusicale.class);
            startActivity(intent);
        }
        else
        {
            new AlertDialog.Builder(LoginActivity.this)
            .setTitle("Fine del Round!")
            //.setMessage("Terminare round?")
            //.setNegativeButton(android.R.string.no, null)
            .setPositiveButton(android.R.string.ok, new OnClickListener() {

                public void onClick(DialogInterface arg0, int arg1) {
                    finish();
                }
            }).create().show();
        }
    }

}

}

Answer 1

Your return type from doInBackground() and receiving type in onPostExecute() does not match

try like this

class CheckUser extends AsyncTask<String, String, Integer> 

protected Integer doInBackground(String... args)

protected void onPostExecute(Integer valoreOnPostExecute)