Flutter Calculator App UI

Published December 26, 2021

In this flutter example tutorial we will create simple calculator App UI with flutter and android studio. This UI contains all numbers buttons and math operation symbols to make addition,multiplications,division and subtraction.

To create calculator buttons we used Column, Container, MaterialButton and Text widgets.

Let's get started

Step 1: Create Flutter application in android studio

Step 2: Create Buttons UI

Widget buildButton(String ButtonVal){
  return Expanded(
      child: Container(
        padding: EdgeInsets.all(0.0),
        margin: EdgeInsets.all(10.0),
        decoration: BoxDecoration(
          color: Colors.green,
          borderRadius: BorderRadius.all(Radius.circular(15.0)),
          boxShadow: [
            BoxShadow(
                color: Colors.blueAccent,
                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: 18.0,color: Colors.white
          ),),
          onPressed: ()=>
              buttonPressed(ButtonVal)
          ,
        ),
      )
  );

}

Step 3: Now design our layout to add all buttons with Symbols and numbers

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("="),
      ],
    )
  ],
),

Step 4: Complete example code for Calculator app UI

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){

  }

  Widget buildButton(String ButtonVal){
    return Expanded(
        child: Container(
          padding: EdgeInsets.all(0.0),
          margin: EdgeInsets.all(10.0),
          decoration: BoxDecoration(
            color: Colors.green,
            borderRadius: BorderRadius.all(Radius.circular(15.0)),
            boxShadow: [
              BoxShadow(
                  color: Colors.blueAccent,
                  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: 18.0,color: Colors.white
            ),),
            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(color: Colors.red,thickness: 2,),
                ),
                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("="),
                      ],
                    )
                  ],
                ),
              ],
            ),
          )
      ),
    );
  }
}

Conclusion: We have create simple Flutter calculator app UI. If you implement logic for calculator app contact with us we will publish them other users to learn more.

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