Day 3 30DaysOfCode May2020 Mobile Beginner MajorE

day330.dart

import 'package:flutter/material.dart';

void main() {
  runApp(
    MaterialApp(
      home: Scaffold(
        body: BarnCounter(),
      ),
    ),
  );
}

class BarnCounter extends StatefulWidget {
  BarnCounterState createState() => BarnCounterState();
}

class BarnCounterState extends State<BarnCounter> {
  int numberOfHeads = 0;
  int numberOfLegs = 0;

  String output = "Input your head and leg values and click 'Count Your Barn'";
//<MAIN CALCULATION FUNCTION IS HERE>
  void countTheBarn() {
    int chickensInTheBarn = ((4 * numberOfHeads) - numberOfLegs) ~/ 2;
    int goatsInTheBarn = (numberOfHeads - chickensInTheBarn);
//</MAIN CALCULATION FUNCTION IS HERE>
    setState(() {
      if (chickensInTheBarn < 0 || goatsInTheBarn < 0)
        output = 'You may have counted wrong. Cannot have negative animals';
      else
        output =
            'You have $goatsInTheBarn goats and $chickensInTheBarn chickens';
    });
  }

  @override
  Widget build(BuildContext context) {
    return Column(children: <Widget>[
      Text('Here! Solve your barn count problem'),
      Row(children: <Widget>[
        Expanded(
          flex: 3,
          child: TextField(
            onChanged: (value) {
              numberOfHeads = int.parse(value);
            },
            decoration: InputDecoration(labelText: 'Enter Number of HEADS'),
          ),
        ),
        Spacer(),
        Expanded(
          flex: 3,
          child: TextField(
            onChanged: (value) {
              numberOfLegs = int.parse(value);
            },
            decoration: InputDecoration(labelText: 'Enter Number of LEGS'),
          ),
        )
      ]),
      FlatButton(child: Text('Count Your Barn'), onPressed: countTheBarn),
      Text(output, style: TextStyle(fontSize: 20))
    ]);
  }
}