i get an UnimplementedError in my flutter app and i have not seen any other questions that really helps me with my problem thats why i ask.

i get an UnimplemetedError but i don't know how to fix it properly without having other errors. like "uid is undefined"

so can anyone help me with this error and make the app error free

thank you very much :)

import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:hetmaantje/utils1/colors.dart';


class todolist extends StatefulWidget {
  @override
  _todolistState createState() => _todolistState();
}

class _todolistState extends State<todolist> {
  String todoTitle = "";
  

  createTodos() {
    @override
    final FirebaseAuth auth = FirebaseAuth.instance;
      final User? user = auth.currentUser;
      final uid = user?.uid;

    DocumentReference documentReference =
        FirebaseFirestore.instance.collection(uid!).doc(todoTitle);

    //Map
    Map<String, String> todos = {"todoTitle": todoTitle};

    documentReference.set(todos).whenComplete(() {
      print("$todoTitle created");
    });
  }

  deleteTodos(item) {
@override
      final User? user = auth.currentUser;
      final uid = user?.uid;
    DocumentReference documentReference =
    FirebaseFirestore.instance.collection(uid!).doc(item);

    documentReference.delete().whenComplete(() {
      print("$item deleted");

    });
  }

  @override
  final FirebaseAuth auth = FirebaseAuth.instance;
  @override
  void inputData() {
    final User? user = auth.currentUser;
    final uid = user?.uid;
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("To-do lijst"),
      ),
      floatingActionButton: FloatingActionButton(
        backgroundColor:  hexStringToColor("fe98a8"),
        onPressed: () {
          showDialog(
              context: context,
              builder: (BuildContext context) {
                return AlertDialog(
                  backgroundColor:  hexStringToColor("fe98a8"),
                  shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(8)),
                  title: Text("Voeg een nieuwe taak toe"),
                  content: TextField(
                    onChanged: (String value) {
                      todoTitle = value;
                    },
                  ),
                  actions: <Widget>[
                    TextButton(
                onPressed:() {
                  createTodos();
                  Navigator.of(context).pop();
                },
                child: Text("Add"))
                ],
                );
              });
        },
        child: Icon(
          Icons.add,
          color: Colors.white,
        ),
      ),
      body: StreamBuilder(
          stream: FirebaseFirestore.instance.collection(uid!).snapshots(),
          builder: (context, snapshots) {
            if (snapshots.hasData) {
              return ListView.builder(
                  shrinkWrap: true,
                  itemCount: snapshots.data?.docs.length,
                  itemBuilder: (context, index) {
                    DocumentSnapshot documentSnapshot =
                    snapshots.data!.docs[index];
                    return Dismissible(
                        onDismissed: (direction) {
                          deleteTodos(documentSnapshot["todoTitle"]);
                        },
                        key: Key(documentSnapshot["todoTitle"]),
                        child: Card(
                          elevation: 4,
                          margin: EdgeInsets.all(8),
                          shape: RoundedRectangleBorder(
                              borderRadius: BorderRadius.circular(8)),
                          child: ListTile(
                            title: Text(documentSnapshot["todoTitle"]),
                            trailing: IconButton(
                                icon: Icon(
                                  Icons.delete,
                                  color: Colors.red,
                                ),
                                onPressed: () {
                                  deleteTodos(documentSnapshot["todoTitle"]);
                                }),
                          ),
                        ));
                  });
            } else {
              return Align(
                alignment: FractionalOffset.bottomCenter,
                child: CircularProgressIndicator(),
              );
            }
          }),
    );
  }}

  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    throw UnimplementedError();
  }






  
}

CodePudding user response：

There are format issue on your code. You need to add override over build method and remove bottom build method and close the function properly.

class todolist extends StatefulWidget {
  @override
  _todolistState createState() => _todolistState();
}

class _todolistState extends State<todolist> {
  String todoTitle = "";

  createTodos() {
    final FirebaseAuth auth = FirebaseAuth.instance;
    final User? user = auth.currentUser;
    final uid = user?.uid;

    DocumentReference documentReference =
        FirebaseFirestore.instance.collection(uid!).doc(todoTitle);

    //Map
    Map<String, String> todos = {"todoTitle": todoTitle};

    documentReference.set(todos).whenComplete(() {
      print("$todoTitle created");
    });
  }

  deleteTodos(item) {
    @override
    final User? user = auth.currentUser;
    final uid = user?.uid;
    DocumentReference documentReference =
        FirebaseFirestore.instance.collection(uid!).doc(item);

    documentReference.delete().whenComplete(() {
      print("$item deleted");
    });
  }

  final FirebaseAuth auth = FirebaseAuth.instance;

  late final User? user = auth.currentUser;
  late final uid = user?.uid;
  late final stream = FirebaseFirestore.instance.collection(uid!).snapshots();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("To-do lijst"),
      ),
      floatingActionButton: FloatingActionButton(
        backgroundColor: hexStringToColor("fe98a8"),
        onPressed: () {
          showDialog(
              context: context,
              builder: (BuildContext context) {
                return AlertDialog(
                  backgroundColor: hexStringToColor("fe98a8"),
                  shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(8)),
                  title: Text("Voeg een nieuwe taak toe"),
                  content: TextField(
                    onChanged: (String value) {
                      todoTitle = value;
                    },
                  ),
                  actions: <Widget>[
                    TextButton(
                        onPressed: () {
                          createTodos();
                          Navigator.of(context).pop();
                        },
                        child: Text("Add"))
                  ],
                );
              });
        },
        child: Icon(
          Icons.add,
          color: Colors.white,
        ),
      ),
      body: StreamBuilder(
          stream: stream,
          builder: (context, snapshots) {
            if (snapshots.hasData) {
              return ListView.builder(
                  shrinkWrap: true,
                  itemCount: snapshots.data?.docs.length,
                  itemBuilder: (context, index) {
                    DocumentSnapshot documentSnapshot =
                        snapshots.data!.docs[index];
                    return Dismissible(
                        onDismissed: (direction) {
                          deleteTodos(documentSnapshot["todoTitle"]);
                        },
                        key: Key(documentSnapshot["todoTitle"]),
                        child: Card(
                          elevation: 4,
                          margin: EdgeInsets.all(8),
                          shape: RoundedRectangleBorder(
                              borderRadius: BorderRadius.circular(8)),
                          child: ListTile(
                            title: Text(documentSnapshot["todoTitle"]),
                            trailing: IconButton(
                                icon: Icon(
                                  Icons.delete,
                                  color: Colors.red,
                                ),
                                onPressed: () {
                                  deleteTodos(documentSnapshot["todoTitle"]);
                                }),
                          ),
                        ));
                  });
            } else {
              return Align(
                alignment: FractionalOffset.bottomCenter,
                child: CircularProgressIndicator(),
              );
            }
          }),
    );
  }
}