Flutter -将来自不同文本字段的值​相乘

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Multiply',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MultiplyScreen(),
    );
  }
}

class MultiplyScreen extends StatefulWidget {
  @override
  _MultiplyScreenState createState() => _MultiplyScreenState();
}

class _MultiplyScreenState extends State<MultiplyScreen> {
  TextEditingController _number1Controller = TextEditingController();
  TextEditingController _number2Controller = TextEditingController();
  String _result = '';

  void _multiplyNumbers() {
    double number1 = double.tryParse(_number1Controller.text) ?? 0;
    double number2 = double.tryParse(_number2Controller.text) ?? 0;
    double result = number1 * number2;
    setState(() {
      _result = 'Result: $result';
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Multiply'),
      ),
      body: Padding(
        padding: EdgeInsets.all(16.0),
        child: Column(
          children: [
            TextField(
              controller: _number1Controller,
              keyboardType: TextInputType.number,
              decoration: InputDecoration(labelText: 'Number 1'),
            ),
            TextField(
              controller: _number2Controller,
              keyboardType: TextInputType.number,
              decoration: InputDecoration(labelText: 'Number 2'),
            ),
            SizedBox(height: 16.0),
            ElevatedButton(
              onPressed: _multiplyNumbers,
              child: Text('Multiply'),
            ),
            SizedBox(height: 16.0),
            Text(_result),
          ],
        ),
      ),
    );
  }
}