Drive REST API, Settings Activity, Authorization button

SettingsActivityWithAuthorizationButton.java

public class ActivityWithAuthorizationButton 
        extends ActionBarActivity 
        implements AuthorizationFlow.Callback {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        // Display the fragment as the main content
        initSettingsBox();
        
        // ...
    }

    private void initSettingsBox() {
        if (null == getFragmentManager().findFragmentByTag(SettingsFragment.MANAGER_TAG)) {
            final FragmentTransaction fragmentTransaction = getFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.base_fragment_container, new SettingsFragment(), SettingsFragment.MANAGER_TAG).commit();
        }
    }
    
    // ...

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        final SettingsFragment fragment = findSettingsFragment();
        if (null != fragment && fragment.canHandleOnActivityResult(requestCode, resultCode, data)) return;
        super.onActivityResult(requestCode, resultCode, data);
    }

    @Override
    public void onAuthSucceed(final AuthUserInfo userInfo) {
        // Save info about user
        SettingsManager.getInstance().saveAccountDetails(userInfo);

        // To ensure that it will happen on the UI thread
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                final SettingsFragment fragment = findSettingsFragment();
                if (null != fragment) fragment.onChangeAccount(userInfo.email);
            }
        });
    }

    private SettingsFragment findSettingsFragment() {
        return (SettingsFragment) getFragmentManager().findFragmentByTag(SettingsFragment.MANAGER_TAG);
    }

    //
    // +------------------------------------------------------------+
    // | Settings Fragment                                          |
    // +------------------------------------------------------------+
    // ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

    @TargetApi(Build.VERSION_CODES.HONEYCOMB)
    public static class SettingsFragment extends PreferenceFragment implements Preference.OnPreferenceClickListener {

        public static final String MANAGER_TAG = "<Application Id>.tag#settings";

        private AuthorizationFlow mAuthorizationFlow = new AuthorizationFlow(null);

        @Override
        public void onAttach(Activity activity) {
            mAuthorizationFlow.withActivity(activity);
            super.onAttach(activity);
        }

        // ...

        @Override
        public boolean onPreferenceClick(final Preference preference) {
            if (isAuthorization(preference)) {
                mAuthorizationFlow.authorize();
            } else if (isUnauthorization(preference)) {
                mAuthorizationFlow.unauthorize();
            }

            return false;
        }

        private void onChangeAccount(final String accountDescription) {
            // ...
        }

        private boolean canHandleOnActivityResult(final int requestCode, final int resultCode, final Intent data) {
            return mAuthorizationFlow.handleOnActivityResult(requestCode, resultCode, data);
        }

    }

}