Log.i(TAG, "Username: "+ usernameText.getText().toString());
        Log.i(TAG, "Password: "+ passwordText.getText().toString());
        AWSMobileClient.getInstance().signIn(usernameText.getText().toString(), passwordText.getText().toString(), null, new Callback<SignInResult>() {
            @Override
            public void onResult(final SignInResult signInResult) {
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        Log.d(TAG, "Sign-in callback state: " + signInResult.getSignInState());
                        switch (signInResult.getSignInState()) {
                            case DONE:
                                Log.i(TAG, "Sign-in done.");
                                Intent i = new Intent(LoginActivity.this, MainActivity.class);
                                startActivity(i);
                                break;
                            case SMS_MFA:
                                Log.i(TAG, "Please confirm sign-in with SMS.");
                                break;
                            case NEW_PASSWORD_REQUIRED:
                                Log.i(TAG, "Please confirm sign-in with new password.");
                                break;
                            default:
                                Log.i(TAG, "Unsupported sign-in confirmation: " + signInResult.getSignInState());
                                break;
                        }
                    }
                });
            }

            @Override
            public void onError(Exception e) {
                Log.e(TAG, "Sign-in error", e);
            }
        });