您可以使用这种方法
main.dart

void main() {
const String heightValue="195";
const String weightValue= "80";
final int result = Utils.calculatePressed(heightValue,weightValue);
print('Your Bmi is \n\n $result');
}

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utils.dart

abstract class Utils{
    static  int  calculatePressed( String x, String y) {
   
    int cTall = int.parse(x);
    int dWeight = int.parse(y);
    double dTall = cTall / 100;
    int bmi = (dWeight / dTall * dTall).toInt();
  
    return bmi;
  }
}

型

这就是你可以在Flutter中做的事情。

的数据

主省道

import 'package:flutter/material.dart';

import 'home_page.dart';

void main() {
  runApp(const MainApp());
}

class MainApp extends StatelessWidget {
  const MainApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: HomePage(),
    );
  }
}

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主页.dart

import 'package:flutter/material.dart';

import 'util.dart';

class HomePage extends StatefulWidget {
  const HomePage({super.key});

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  final TextEditingController _heightController = TextEditingController();
  final TextEditingController _weightController = TextEditingController();

  int? _bmi;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: Padding(
        padding: const EdgeInsets.symmetric(
          horizontal: 20,
        ),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: [
            TextFormField(
              controller: _heightController,
              decoration:
                  const InputDecoration(helperText: "Enter Height in cm"),
            ),
            TextFormField(
              controller: _weightController,
              decoration:
                  const InputDecoration(helperText: "Enter Weight in KG"),
            ),
            ElevatedButton(
              onPressed: () {
                setState(() {
                  _bmi = calculatePressed(
                      _heightController.text, _weightController.text);
                });
              },
              child: const Text("Calculate BMI"),
            ),
            (_bmi != null)
                ? Text(
                    "Your Bmi is \n\n $_bmi",
                  )
                : const SizedBox(
                    height: 0,
                  ),
          ],
        ),
      ),
    );
  }
}

型

utils.dart

calculatePressed(String height, String wt) {
  var tall = height.toString();
  var weight = wt.toString();
  var cTall = int.parse(tall);
  var dWeight = int.parse(weight);
  var dTall = cTall / 100;
  var bmi = (dWeight / dTall * dTall).toInt();
  // var result = 'Your Bmi is \n\n $bmi';
  return bmi;
}

型