[英]Returning a value from class in flutter after Raisedbutton
我正在構建我的第一個應用程序來計算我工作所需的值。 我已經在 Python 中進行了這項工作,但這真的很不一樣。 我有一個 textformfield,我在其中輸入了“我需要的數據”。 成功后,我從“onPress”按鈕調用一個類並傳遞數據。 計算后,我需要將計算值顯示在文本字段 (spev) 中。 如何將“Buisber”類的值返回到文本字段。 我找了幾天,但找不到。 我確定我在某處讀過它,但就是不明白。 這是一個剝離版本:
import 'package:flutter/material.dart';
void main() {
runApp(MaterialApp(
home: Buis(),
));
}
class Buis extends StatelessWidget {
@override
Widget build(BuildContext context) {
String spev = '0';
TextEditingController kapController = TextEditingController(text: '10.60');
return Scaffold(
appBar: AppBar(
title: Center(
child: Text("Power Outcome"),
),
),
body: Center(
child: Container(
decoration: BoxDecoration(
),
child: SingleChildScrollView(
child: Column(
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
SizedBox(height: 20),
Column(
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
// Calculate
Center(
child: RaisedButton(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(18.0),
side: BorderSide(color: Colors.red)),
onPressed: () {
Buisber(
kapController.text);
},
color: Colors.blue,
textColor: Colors.white,
child: Text("Calculate".toUpperCase(),
style: TextStyle(fontSize: 14)),
),
),
// Outcome Spev
Container(
alignment: Alignment(0, 0),
width: 80,
height: 30,
decoration: BoxDecoration(
borderRadius: BorderRadius.horizontal(
left: Radius.circular(40),
right: Radius.circular(40),
),
border: Border.all(width: 1.0),
),
child: Text(
'$spev',
style: TextStyle(
fontSize: 15,
),
),
),
SizedBox(height: 10),
],
),
],
),
),
),
),
);
}
}
class Buisber {
Buisber(kap) {
var kap1 = double.parse(kap);
print(kap1);
var spev = 1.7 * (50 / kap1);
spev = num.parse(spev.toStringAsFixed(2));
//testing (print works)
//how to send back Outcome Spev
print("Spev is " '$spev');
}
}
@Pim,為什么不創建一個函數而不是類並在 Stateful 小部件中接收值? 然后您可以刷新狀態以更新值,如下所示,
void main() {
runApp(new Buis());
}
class Buis extends StatefulWidget {
@override
BuisState createState() => BuisState();
}
class BuisState extends State<Buis> {
var value = '';
@override
Widget build(BuildContext context) {
String spev = '0';
TextEditingController kapController = TextEditingController(text: '10.60');
return MaterialApp(home: Scaffold(
appBar: AppBar(
title: Center(
child: Text("Power Outcome"),
),
),
body: Center(
child: Container(
decoration: BoxDecoration(
),
child: SingleChildScrollView(
child: Column(
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
SizedBox(height: 20),
Column(
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
// Calculate
Center(
child: RaisedButton(
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(18.0),
side: BorderSide(color: Colors.red)),
onPressed: () {
value = getValue(kapController.text).toString();
setState(() {});
},
color: Colors.blue,
textColor: Colors.white,
child: Text("Calculate".toUpperCase(),
style: TextStyle(fontSize: 14)),
),
),
// Outcome Spev
Container(
alignment: Alignment(0, 0),
width: 80,
height: 30,
decoration: BoxDecoration(
borderRadius: BorderRadius.horizontal(
left: Radius.circular(40),
right: Radius.circular(40),
),
border: Border.all(width: 1.0),
),
child: Text(
value.toString(),
style: TextStyle(
fontSize: 15,
),
),
),
SizedBox(height: 10),
],
),
],
),
),
),
),
)
);
}
}
// This can be within your BuisState
getValue (kap) {
var kap1 = double.parse(kap);
print(kap1);
var spev = 1.7 * (50 / kap1);
spev = num.parse(spev.toStringAsFixed(2));
//testing (print works)
//how to send back Outcome Spev
print("Spev is " '$spev');
return spev;
}
希望這可以幫助。
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