Flutter Realtime textfield validation

login.dart

// import the validator


class Login extends StatefulWidget {

  @override
  _LoginState createState() => _LoginState();
}

class _LoginState extends State<Login> {
  TextEditingController loginEmailController = TextEditingController();

  bool get isPopulated =>
      loginEmailController.text.isNotEmpty;

  bool isLoginButtonEnabled(LoginState state) {
    return state.isFormValid && isPopulated && !state.isSubmitting;
  }

  void _onEmailChanged() {
    _loginBloc.add(
      EmailChanged(email: loginEmailController.text),
    );
  }


 

  @override
  void initState() {
    super.initState();
    _loginBloc = BlocProvider.of<LoginBloc>(context);
    loginEmailController.addListener(_onEmailChanged);
  }

  @override
  Widget build(BuildContext context) {
    return child: Form(
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  children: <Widget>[
                    Padding(
                      padding: const EdgeInsets.only(
                          top: 25, left: 10, right: 10, bottom: 10),
                      child: TextFormField(
                        controller: loginEmailController,
                        keyboardType: TextInputType.emailAddress,
                        autovalidate: true,
                        autocorrect: false,
                        validator: (_){
                          Validators.isValidEmail(loginEmailController.text);
                        },
                        decoration: InputDecoration(
                          labelText: "Email address",
                          prefixIcon: Icon(Icons.email),
                        ),
                      ),
                    ),
                   
                    Padding(
                      padding: const EdgeInsets.symmetric(vertical: 10),
                      child: RaisedButton(
                        child: Text(
                          "LOGIN",
                          style: TextStyle(
                              letterSpacing: 0.6,
                              color: Colors.white,
                              fontWeight: FontWeight.bold),
                        ),
                        onPressed(){
                        }
                        
                      ),
                    ),
                  ],
                ),
              );
      
    
  }
}

validator.dart

class Validators {
  static final RegExp _emailRegExp = RegExp(
    r'^[a-zA-Z0-9.!#$%&’*+/=?^_`{|}~-]+@[a-zA-Z0-9-]+(?:\.[a-zA-Z0-9-]+)*$',
  );
}

Important import the validator