A Caculator App project for demonstrating Flutter.

main.dart

import 'package:flutter/material.dart';

import 'package:provider/provider.dart';



import 'package:caculator/daos/cacu_dao.dart';

import 'package:caculator/daos/value_viewer_dao.dart';

import 'package:caculator/screens/caculate_screen.dart';



void main() {

  runApp(

    MultiProvider(

      providers: [

        ChangeNotifierProvider(create: (_)=> CacuDao()),

        ChangeNotifierProvider(create: (_) => ValueViewerDao())],

      child: const AppEntryPoint()

    )

  );

}



class AppEntryPoint extends StatelessWidget {

  const AppEntryPoint({super.key});



  @override

  Widget build(BuildContext context) {

    return MaterialApp(

      title: 'Caculator',

      theme: ThemeData(

        primarySwatch: Colors.blueGrey,

      ),

      routes: {

        "/caculate":(BuildContext context) => CaculateScreen(),

      },        

      initialRoute: "/caculate",

    );

  }

}

models\cacu.dart

class Cacu {

    String cacuValue;   // Value for caculate

    CacuType cacuType;  // Caculate type



    Cacu(this.cacuValue, this.cacuType);

}



enum CacuType {

  none,

  addition,

  subtraction,

  multiplication,

  division,

}

daos\cacu_dao.dart

import 'package:flutter/material.dart';



import 'package:caculator/models/cacu.dart';



class CacuDao extends ChangeNotifier {

  List<Cacu> cacuList = [];

  

  List<Cacu> getCacus() {

    return cacuList;

  }



  /// Insert value for caculate later

  void insertCacu(Cacu cacu) {

    cacuList.add(cacu);



    notifyListeners();

  }



  /// Update caculate type to value

  void clearCacu() {

    cacuList.clear();



    notifyListeners();

  } 

}

daos\value_viewer_dao.dart

import 'package:flutter/material.dart';



class ValueViewerDao extends ChangeNotifier {

  double value = 0;

 

  /// Update caculate type to value

  void updateValue(double value) {

    this.value = value;



    notifyListeners();

  } 

}

components\common_functions.dart

import 'package:caculator/models/cacu.dart';



class CommonFunctions {

  static String getCacuSign(CacuType cacuType) {

    switch (cacuType) {

      case CacuType.addition:

        return "+";

      case CacuType.subtraction:

        return "-";

      case CacuType.multiplication:

        return "x";

      case CacuType.division:

        return "÷";

      default:

        return "";

    }

  }

}

cacu_component.dart

import 'package:flutter/material.dart';



import 'package:caculator/models/cacu.dart';

import 'package:caculator/components/common_functions.dart';



// ignore: must_be_immutable

class CacuComponent extends StatefulWidget {

  Cacu cacu;



  CacuComponent(this.cacu, {super.key});



  @override

  State createState() {

    return _CacuComponent();

  }

}



class _CacuComponent extends State<CacuComponent> {

  @override

  Widget build(BuildContext context) {

    Widget cacuValueText = Text(

      widget.cacu.cacuValue,

    );



    Widget cacuTypeText = Text(

      CommonFunctions.getCacuSign(widget.cacu.cacuType),

    );



    return Card(

      child: ListTile(

        title: Row(children: [

          cacuValueText,

          const SizedBox(width: 10),

          cacuTypeText,

        ]),

      ),

    );

  }

}

screens\caculate_screen.dart

import 'dart:async';



import 'package:caculator/components/common_functions.dart';

import 'package:flutter/material.dart';

import 'package:provider/provider.dart';



import 'package:caculator/daos/cacu_dao.dart';

import 'package:caculator/components/cacu_component.dart';

import 'package:caculator/models/cacu.dart';



// ignore: must_be_immutable

class CaculateScreen extends StatefulWidget {

  CaculateScreen({super.key});



  Cacu currentCacu = Cacu('0', CacuType.none);



  @override

  State createState() {

    return _CaculateScreen();

  }

}



class _CaculateScreen extends State<CaculateScreen> {

  final ScrollController _scrollController = ScrollController();



  @override

  Widget build(BuildContext context) {

    Timer(const Duration(milliseconds: 500), () => _scrollController.jumpTo(_scrollController.position.maxScrollExtent));



    Widget valueViewer = Row(

      mainAxisAlignment: MainAxisAlignment.center,

      children: [

        Container(

        width: 250,

        margin: const EdgeInsets.all(15.0),

        padding: const EdgeInsets.all(3.0),

        decoration: BoxDecoration(

        border: Border.all(color: Colors.blueAccent)

        ),

        child: Text(

          widget.currentCacu.cacuValue,

          textAlign: TextAlign.right,

          style: const TextStyle(fontSize: 20),),

        ),

        Text(CommonFunctions.getCacuSign(widget.currentCacu.cacuType)),

      ],

    );



    Widget keybooards = Column(children: [

      Row(

        mainAxisAlignment: MainAxisAlignment.center,

        children: [

          SizedBox(

            width: 70.0,

            child: OutlinedButton(

              child: const Text('AC',

                overflow: TextOverflow.clip,

                maxLines: 1,

                softWrap: false,

              ),

              onPressed: (){

                setState(() {

                  widget.currentCacu = Cacu('0', CacuType.none);

                  context.read<CacuDao>().clearCacu();

                });

              },

            )

          ),

          const SizedBox(width: 5),

          OutlinedButton(

            child: const Text('C'),

            onPressed: (){

              setState(() {

                  widget.currentCacu = Cacu('0', CacuType.none);

              });

            },

          ),

          const SizedBox(width: 5),          

          OutlinedButton(

            child: const Text('±'),

            onPressed: (){

              setState(() {

                if(widget.currentCacu.cacuValue[0] == '-'){

                  widget.currentCacu.cacuValue = widget.currentCacu.cacuValue.substring(1);

                }

                else {

                widget.currentCacu.cacuValue = '-${widget.currentCacu.cacuValue}';

                }

              });

            },

          ),

          const SizedBox(width: 5),     

          OutlinedButton(

            child: const Text('÷'),

            onPressed: (){

              setState(() {

                  widget.currentCacu.cacuType = CacuType.division;

              });

            }

          ),

        ]

      ),

      const SizedBox(height: 5),

      Row(

        mainAxisAlignment: MainAxisAlignment.center,

        children: [

          OutlinedButton(

            child: const Text('7'),

            onPressed: (){

              setState(() {

                String num = '7';

                if(widget.currentCacu.cacuType == CacuType.none) {

                  if(widget.currentCacu.cacuValue == '0') {

                    widget.currentCacu.cacuValue = num;

                  } else {

                    widget.currentCacu.cacuValue = widget.currentCacu.cacuValue + num;

                  }

                }

                else {

                  context.read<CacuDao>().insertCacu(widget.currentCacu);

                  widget.currentCacu = Cacu(num, CacuType.none);

                }

              });

            }

          ),

          const SizedBox(width: 5),  

          OutlinedButton(

            child: const Text('8'),

            onPressed: (){

              setState(() {

                String num = '8';

                if(widget.currentCacu.cacuType == CacuType.none) {

                  if(widget.currentCacu.cacuValue == '0') {

                    widget.currentCacu.cacuValue = num;

                  } else {

                    widget.currentCacu.cacuValue = widget.currentCacu.cacuValue + num;

                  }

                }

                else {

                  context.read<CacuDao>().insertCacu(widget.currentCacu);

                  widget.currentCacu = Cacu(num, CacuType.none);

                }

              });

            }

          ),

          const SizedBox(width: 5),

          OutlinedButton(

            child: const Text('9'),

            onPressed: (){

              setState(() {

                String num = '9';

                if(widget.currentCacu.cacuType == CacuType.none) {

                  if(widget.currentCacu.cacuValue == '0') {

                    widget.currentCacu.cacuValue = num;

                  } else {

                    widget.currentCacu.cacuValue = widget.currentCacu.cacuValue + num;

                  }

                }

                else {

                  context.read<CacuDao>().insertCacu(widget.currentCacu);

                  widget.currentCacu = Cacu('0', CacuType.none);

                }

              });

            }

          ),

          const SizedBox(width: 10),

          OutlinedButton(

            child: const Text('x'),

            onPressed: (){

              setState(() {

                  widget.currentCacu.cacuType = CacuType.multiplication;

              });

            }

          ),

        ],

      ),

      const SizedBox(height: 5),

      Row(

        mainAxisAlignment: MainAxisAlignment.center,

        children: [

          OutlinedButton(

            child: const Text('4'),

            onPressed: (){

              setState(() {

                String num = '4';

                if(widget.currentCacu.cacuType == CacuType.none) {

                  if(widget.currentCacu.cacuValue == '0') {

                    widget.currentCacu.cacuValue = num;

                  } else {

                    widget.currentCacu.cacuValue = widget.currentCacu.cacuValue + num;

                  }

                }

                else {

                  context.read<CacuDao>().insertCacu(widget.currentCacu);

                  widget.currentCacu = Cacu(num, CacuType.none);

                }

              });

            }

          ),

          const SizedBox(width: 5),  

          OutlinedButton(

            child: const Text('5'),

            onPressed: (){

              setState(() {

                String num = '5';

                if(widget.currentCacu.cacuType == CacuType.none) {

                  if(widget.currentCacu.cacuValue == '0') {

                    widget.currentCacu.cacuValue = num;

                  } else {

                    widget.currentCacu.cacuValue = widget.currentCacu.cacuValue + num;

                  }

                }

                else {

                  context.read<CacuDao>().insertCacu(widget.currentCacu);

                  widget.currentCacu = Cacu(num, CacuType.none);

                }

              });

            }

          ),

          const SizedBox(width: 5),

          OutlinedButton(

            child: const Text('6'),

            onPressed: (){

              setState(() {

                String num = '6';

                if(widget.currentCacu.cacuType == CacuType.none) {

                  if(widget.currentCacu.cacuValue == '0') {

                    widget.currentCacu.cacuValue = num;

                  } else {

                    widget.currentCacu.cacuValue = widget.currentCacu.cacuValue + num;

                  }

                }

                else {

                  context.read<CacuDao>().insertCacu(widget.currentCacu);

                  widget.currentCacu = Cacu(num, CacuType.none);

                }

              });

            }

          ),

          const SizedBox(width: 10),

          OutlinedButton(

            child: const Text('-'),

            onPressed: (){

              setState(() {

                  widget.currentCacu.cacuType = CacuType.subtraction;

              });

            }

          ),

        ],

      ),

      const SizedBox(height: 5),

      Row(

        mainAxisAlignment: MainAxisAlignment.center,

        children: [

          OutlinedButton(

            child: const Text('1'),

            onPressed: (){

              setState(() {

                String num = '1';

                if(widget.currentCacu.cacuType == CacuType.none) {

                  if(widget.currentCacu.cacuValue == '0') {

                    widget.currentCacu.cacuValue = num;

                  } else {

                    widget.currentCacu.cacuValue = widget.currentCacu.cacuValue + num;

                  }

                }

                else {

                  context.read<CacuDao>().insertCacu(widget.currentCacu);

                  widget.currentCacu = Cacu(num, CacuType.none);

                }

              });

            }

          ),

          const SizedBox(width: 5),  

          OutlinedButton(

            child: const Text('2'),

            onPressed: (){

              setState(() {

                String num = '2';

                if(widget.currentCacu.cacuType == CacuType.none) {

                  if(widget.currentCacu.cacuValue == '0') {

                    widget.currentCacu.cacuValue = num;

                  } else {

                    widget.currentCacu.cacuValue = widget.currentCacu.cacuValue + num;

                  }

                }

                else {

                  context.read<CacuDao>().insertCacu(widget.currentCacu);

                  widget.currentCacu = Cacu(num, CacuType.none);

                }

              });

            }

          ),

          const SizedBox(width: 5),

          OutlinedButton(

            child: const Text('3'),

            onPressed: (){

              setState(() {

                String num = '3';

                if(widget.currentCacu.cacuType == CacuType.none) {

                  if(widget.currentCacu.cacuValue == '0') {

                    widget.currentCacu.cacuValue = num;

                  } else {

                    widget.currentCacu.cacuValue = widget.currentCacu.cacuValue + num;

                  }

                }

                else {

                  context.read<CacuDao>().insertCacu(widget.currentCacu);

                  widget.currentCacu = Cacu(num, CacuType.none);

                }

              });

            }

          ),

          const SizedBox(width: 10),

          OutlinedButton(

            child: const Text('+'),

            onPressed: (){

              setState(() {

                  widget.currentCacu.cacuType = CacuType.addition;

              });

            }

          ),

        ],

      ),

      const SizedBox(height: 5),

      Row(

        mainAxisAlignment: MainAxisAlignment.center,

        children: [

          SizedBox(

            width: 130.0,

            child: OutlinedButton(

              child: const Text('0'),

              onPressed: (){

                setState(() {

                  String num = '0';

                  if(widget.currentCacu.cacuType == CacuType.none) {

                    if(widget.currentCacu.cacuValue != '0' && !widget.currentCacu.cacuValue.contains('.')) {

                      widget.currentCacu.cacuValue = widget.currentCacu.cacuValue + num;

                    }

                  }

                  else {

                    context.read<CacuDao>().insertCacu(widget.currentCacu);

                    widget.currentCacu = Cacu(num, CacuType.none);

                  }

                });

              }

            ),

          ),

          const SizedBox(width: 5),  

          OutlinedButton(

            child: const Text('.'),

            onPressed: (){

                  String num = '.';

                  if(widget.currentCacu.cacuType == CacuType.none) {

                    if(!widget.currentCacu.cacuValue.contains('.')) {

                      widget.currentCacu.cacuValue = widget.currentCacu.cacuValue + num;

                    }

                  }

                  else {

                    context.read<CacuDao>().insertCacu(widget.currentCacu);

                    widget.currentCacu = Cacu('0', CacuType.none);

                  }

            }

          ),

          const SizedBox(width: 10),

          OutlinedButton(

            child: const Text('='),

            onPressed: (){

              setState(() {

                double result = 0;

                CacuType lastCacuType = CacuType.none;



                List<Cacu> cacus = context.read<CacuDao>().getCacus();

                cacus.add(Cacu(widget.currentCacu.cacuValue, CacuType.none));

                for (var cacu in cacus) {

                  switch(lastCacuType) {

                    case CacuType.division:

                      result = result / double.parse(cacu.cacuValue);

                    case CacuType.multiplication:

                      result = result * double.parse(cacu.cacuValue);

                    case CacuType.subtraction:

                      result = result - double.parse(cacu.cacuValue);

                    case CacuType.addition:

                      result = result + double.parse(cacu.cacuValue);

                    default:

                      result = double.parse(cacu.cacuValue);

                  }

                  lastCacuType = cacu.cacuType;

                }



                widget.currentCacu = Cacu(result.toString(), CacuType.none);



                context.read<CacuDao>().clearCacu();

              });

            }

          ),

        ],

      ),

      const SizedBox(height: 5),

    ]);

    

    return Scaffold(

      appBar: AppBar(title: const Text("Caculator"),),

      body: Container(

        alignment: Alignment.topCenter,

        child: Column(

          children: [

            Expanded(

              child: ListView(

                controller: _scrollController,

                children: [

                  ...context.watch<CacuDao>().getCacus().map((e) => CacuComponent(e)).toList(),

                ],

              ),

            ),

            valueViewer,

            keybooards,

          ]

        ),

      ),

    );

  }

}