How to access methods in one class an call it in another classes method in flutter (dart)

Question

I have a method called handleSignIn. I want to call it inside a class that handles sign in when the screen orientantion is mobile. How can I access the method from one class to another class?

this is my first class

class _SignInState extends State<SignIn> {

  @override
  void initState() {
    super.initState();
    MsalMobile.create('assets/auth_config.json', authority).then((client) {
      setState(() {
        msal = client;
      });
      refreshSignedInStatus();
    });
  }

  /// Signs a user in
  void handleSignIn() async {
    await msal.signIn(null, [SCOPE]).then((result) {
      // ignore: unnecessary_statements
      refreshSignedInStatus();
    }).catchError((exception) {
      if (exception is MsalMobileException) {
        logMsalMobileError(exception);
      } else {
        final ex = exception as Exception;
        print('exception occurred');
        print(ex.toString());
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: () => FocusScope.of(context).unfocus(),
      child: Scaffold(
        backgroundColor: Color(0xff392850),
        body: Responsive(
          mobile: _HomeScreenMobile(
          ),
         // desktop: _HomeScreenDesktop(),
        ),
      ),
    );
  }
}

my _HomeScreenMobile class

class _HomeScreenMobile extends StatelessWidget{
  bool isSignedIn = false;

  Widget build(BuildContext context) {
   ProgressDialog progressDialog  = ProgressDialog(context, type:ProgressDialogType.Normal, isDismissible: false, );
    progressDialog.style(message: "Signing you in ...");
    return Scaffold(
      body: Builder(
        builder: (context) => Stack(
          fit: StackFit.expand,
          children: <Widget>[
            Container(
              width: MediaQuery.of(context).size.width,
              height: MediaQuery.of(context).size.height,
              child: Image.asset('assets/landing.webp',
                  fit: BoxFit.fill,
                  color: Color.fromRGBO(255, 255, 255, 0.6),
                  colorBlendMode: BlendMode.modulate),
            ),
            Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                SizedBox(height: 10.0),
                Container(
                  width: 130.0,
                  child: Align(
                      alignment: Alignment.center,
                      child: RaisedButton(
                          shape: RoundedRectangleBorder(
                              borderRadius: new BorderRadius.circular(30.0)),
                          color: Color(0xffffffff),
                          child: Row(
                            mainAxisAlignment: MainAxisAlignment.start,
                            children: <Widget>[
                              Icon(
                                FontAwesomeIcons.microsoft,
                                color: Color(0xFF01A6F0),
                              ),
                              // Visibility(
                              //   visible: !isSignedIn,
                              SizedBox(width: 10.0),
                              Visibility(
                                visible: !isSignedIn,
                                child: Text(
                                  'Sign in',
                                  style: TextStyle(
                                      color: Colors.black, fontSize: 18.0),
                                ),
                              ),
                            ],
                          ),
                          onPressed: () => {
                            progressDialog.show(),
                            handleSignIn(),
                     
                          })),
                )
              ],
            ),
          ],
        ),
      ),
    );
  }
}

how can I access handleSign from _HomeScreenMobile without it throwing the error The method 'handleSignIn' isn't defined for the type '_HomeScreenMobile'.. Have tried going through the example shared no luck

Answer 1

HomeScreenMobile could get its reference as a parameter and call it whenever it's necessary.

class _HomeScreenMobile extends StatelessWidget{
  bool isSignedIn = false;
  _HomeScreenMobile({this.handleSignInReference});
  final Future<void> Function() handleSignInReference;
...
  onPressed: () => {
     progressDialog.show(),
     handleSignInReference(),
  }
}

Finally, where you call this class:

Responsive(
  mobile: _HomeScreenMobile(
      handleSignInReference:handleSignIn
  ),
)

Answer 2

You could create a handle_signin.dart file:

  void handleSignIn() async {
    await msal.signIn(null, [SCOPE]).then((result) {
      refreshSignedInStatus();
    }).catchError((exception) {
      if (exception is MsalMobileException) {
        logMsalMobileError(exception);
      } else {
        final ex = exception as Exception;
        print('exception occurred');
        print(ex.toString());
      }
    });
  }

Import it wherever you need it:

import './handle_signin.dart`;

And use it:

@override
Widget build() {
 return Scaffold(body: Center(GestureDetector(onTap: () async { await handleSignIn(); })));
}

---

Important note: while the code above might work for your case, it's highly recommended that you consider more sophisticated approaches to state management and Widget communication, such as BLoC.