Get the firebase database registered user in flutter?

import 'package:flutter/material.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:liberin_project_manager/src/screens/Login/enter_mobile_number_screen.dart';
import 'package:liberin_project_manager/src/project_owner/home/project_owner_home_screen.dart';
import 'package:liberin_project_manager/src/screens/home/home_screen.dart';
import 'package:liberin_project_manager/unused/phone_auth_test.dart';


class DashboardPage extends StatefulWidget {
  @override  _DashboardPageState createState() => _DashboardPageState();
}

class _DashboardPageState extends State<DashboardPage> {

  String uid = '';
  getUid() {}

  @override  void initState() {
    this.uid = '';
    FirebaseAuth.instance.currentUser().then((val) {
      setState(() {
        this.uid = val.uid;
      });
    }).catchError((e) {
      print(e);
    });
    super.initState();
  }

  @override  Widget build(BuildContext context) {
    return new Scaffold(
        appBar: new AppBar(
          title: new Text('Dashboard'),
          centerTitle: true,
        ),
        body: Center(
          child: Container(
            child: new Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                new Text('You are now logged in as ${uid}'),
                SizedBox(
                  height: 15.0,
                ),
                new OutlineButton(
                  borderSide: BorderSide(
                      color: Colors.red, style: BorderStyle.solid, width: 3.0),
                  child: Text('Logout'),
                  onPressed: () {
                    FirebaseAuth.instance.signOut().then((action) {
                      Navigator.push(
                          context,
                          MaterialPageRoute(
                              builder: (BuildContext context) => ShowUserTask()));
                    }).catchError((e) {
                      print(e);
                    });
                  },
                ),
              ],
            ),
          ),
        ));
  }
}