我正在开发一个扑动的应用程序,在主屏幕上我有一个按钮打开另一个屏幕,这是一个方法.在那个屏幕上我想要做一些计算,比如取用户输入和更新文本字段,点击按钮方法calculateAmount调用哪个更新变量总数反映在文本字段但文本字段没有更新,它只在更新时按下完成键盘……如何才能完成这项任务.
这是我的代码：
这是我的代码：
import 'package:flutter/material.dart';
void main() {
runApp(new MaterialApp(
debugShowCheckedModeBanner: false,home: new homePage()
));
}
class homePage extends StatefulWidget {
@override
homePageState createState() => new homePageState();
}
class homePageState extends State<homePage> {
double Metal = 0.0;
double total = 0.0;
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text("APP-Title",),backgroundColor: Colors.orange),body: new Container(
child: new Center(
child: new Column(
mainAxisAlignment: MainAxisAlignment.center,children: <Widget>[
new Row(
mainAxisAlignment: MainAxisAlignment.center,children: <Widget>[
new Expanded(child: new RaisedButton.icon(
color: Colors.orange,icon: const Icon(
Icons.info,size: 25.0,color: Colors.white,label: new Text('Calculate',style: new TextStyle(
color: Colors.white
)),onPressed: () {
calculateWindow();
),],)
],)
),);
}
void calculateWindow(){
Navigator.of(context).push(
new MaterialPageRoute(
builder: (context) {
return new Scaffold(
appBar: new AppBar(
title: new Text('Calculator'),backgroundColor: Colors.orange,body: new ListView(
children: <Widget>[
new Row(
crossAxisAlignment: CrossAxisAlignment.center,children: <Widget>[
new Container(
height: 50.0,width: 360.0,decoration: new BoxDecoration(
color: Colors.orange,shape: BoxShape.rectangle,child: new Center(
child: new Row(
children: <Widget>[
new Expanded(
child: new Container(
child: new Text("Gold & Silver in Sold & Ornaments",style: textStyle,textAlign: textAlign
),new Container(
height: 40.0,width: 80.0,decoration: new BoxDecoration(
color: Colors.white),child: new TextField(
keyboardType: TextInputType.number,onSubmitted : (String value) {
try {
Metal = double.parse(value.toString());
print(total);
} catch (exception) {
Metal = 0.0;
}
}
),new Row(
mainAxisAlignment: MainAxisAlignment.center,children: <Widget>[
new Expanded(
child: new Container(
width: 50.0,child: new RaisedButton.icon(
color: Colors.grey,icon: const Icon(
Icons.check,style: new TextStyle(
color: Colors.white,)),onPressed: calculateAmount,new Row(
crossAxisAlignment: CrossAxisAlignment.center,width: 350.0,decoration: new BoxDecoration(
color: Colors.blueGrey,child: new Center(
child: new Row(
children: <Widget>[
new Expanded(
child: new Container(
child: new Text("Total Amount:",style: new TextStyle(
color: Colors.white,textAlign: TextAlign.left,new Container(
child: new Text(
'$total',overflow: TextOverflow.ellipsis,textDirection: TextDirection.ltr,)
),);
},);
}
void calculateAmount(){
setState((){
total = Metal + 0.025;
});
}
}
解决方法
我真的不明白你想要的输出是什么,但是这个例子可能有助于向你展示代码中出错的地方.
class TextFieldEx extends StatefulWidget {
@override
_TextFieldExState createState() => new _TextFieldExState();
}
class _TextFieldExState extends State<TextFieldEx> {
TextEditingController _c ;
double _Metal = 0.0;
double _total = 0.0;
String _text = "initial";
@override
void initState() {
_c = new TextEditingController();
super.initState();
}
@override
Widget build(BuildContext context) {
return new Scaffold(
body: new Center(
child: new Column(
mainAxisAlignment: MainAxisAlignment.center,children: <Widget>[
new TextField(
keyboardType: TextInputType.number,onChanged: (v)=>setState((){_text=v;}),controller: _c,new RaisedButton(
child: new Text("Update"),onPressed: (){
setState((){
_Metal = double.parse(_c.text);
_total = _Metal+0.025;
_c.text = "";
});
},new Text("Text Input: $_text"),new Text("Metal :$_Metal"),new Text("Total:$_total")
],)
)
);
}
}
