Make a Calculator App in Flutter and Android Studio

In this tutorial, I will show you how to make a cool calculator app with a neumorphism design using Flutter and Android Studio.

Source Code:

import 'package:flutter/cupertino.dart';

import 'package:flutter/material.dart';

void main() => runApp(MaterialApp(

  debugShowCheckedModeBanner: false,

  home: HomeApp(),

));

class HomeApp extends StatefulWidget {

  @override

  _HomeAppState createState() => _HomeAppState();

}

class _HomeAppState extends State<HomeApp> {

  String output = "0";

  String _out = "0";

  double num1 = 0.0;

  double num2 = 0.0;

  String operand = "";

  buttonPressed(String btnVal){

    print(btnVal);

    if(btnVal == "C"){

       _out = "0";

       num1 = 0.0;

       num2 = 0.0;

       operand = "";

    }else if(btnVal == "+" || btnVal == "-" || btnVal =="*" || btnVal == "/"){

      num1 = double.parse(output);

      operand = btnVal;

      _out = "0";

      output = output + btnVal;

    }else if(btnVal == "."){

      if(_out.contains(".")){

        print("Already exist");

        return;

      }else{

        _out = _out + btnVal;

      }

    }else if(btnVal == "="){

      num2 = double.parse(output);

      if(operand == "+"){

        _out = (num2 + num1).toString();

      }

      if(operand == "-"){

        _out = (num1 - num2).toString();

      }

      if(operand == "*"){

        _out = (num2 * num1).toString();

      }

      if(operand == "/"){

        _out = (num1 / num2).toString();

      }

      num1 = 0.0;

      num2 = 0.0;

      //_out = "0";

    }else{

      _out = _out+ btnVal;

    }

    setState(() {

      output = double.parse(_out).toStringAsFixed(2);

    });

  }

  Widget buildButton(String ButtonVal){

    return new Expanded(

        child: Container(

          padding: EdgeInsets.all(0.0),

          margin: EdgeInsets.all(10.0),

          decoration: BoxDecoration(

            color: Colors.grey[300],

            borderRadius: BorderRadius.all(Radius.circular(15.0)),

            boxShadow: [

              BoxShadow(

                color: Colors.grey[500],

                offset: Offset(2.0,2.0),

                blurRadius: 8.0,

                spreadRadius: 1.0

              ),

              BoxShadow(

                  color: Colors.white,

                  offset: Offset(-2.0,-2.0),

                  blurRadius: 8.0,

                  spreadRadius: 1.0

              ),

            ],

          ),

          child: MaterialButton(

            padding: EdgeInsets.all(30.0),

            child: Text(ButtonVal, style: TextStyle(

              fontSize: 22.0

            ),),

            onPressed: ()=>

              buttonPressed(ButtonVal)

            ,

          ),

        )

    );

  }

  @override

  Widget build(BuildContext context) {

    return SafeArea(

      child: Scaffold(

        backgroundColor: Colors.grey[300],

        body: Container(

          child: Column(

            children: <Widget>[

              Container(

                alignment: Alignment.centerRight,

                padding: EdgeInsets.symmetric(horizontal:12.0,vertical: 50.0),

                  child: Text(output, style: TextStyle(

                    fontSize: 60.0

                  ),)

              ),

              Expanded(

                child: Divider(),

              ),

              Column(

                children: <Widget>[

                  Row(

                    children: <Widget>[

                      buildButton("."),

                      buildButton("C"),

                      buildButton("<-"),

                      buildButton("*")

                    ],

                  ),

                  Row(

                    children: <Widget>[

                      buildButton("7"),

                      buildButton("8"),

                      buildButton("9"),

                      buildButton("/")

                    ],

                  ),

                  Row(

                    children: <Widget>[

                      buildButton("4"),

                      buildButton("5"),

                      buildButton("6"),

                      buildButton("+")

                    ],

                  ),

                  Row(

                    children: <Widget>[

                      buildButton("1"),

                      buildButton("2"),

                      buildButton("3"),

                      buildButton("-")

                    ],

                  ),

                  Row(

                    children: <Widget>[

                      buildButton("0"),

                      buildButton("="),

                    ],

                  )

                ],

              ),

            ],

          ),

        )

      ),

    );

  }

}