Function 浮动操作按钮赢得';不要叫刷新
我正在制作一个简单的数学应用程序(见下面的代码)。我现在的问题是为什么我的浮动操作按钮(刷新)不能工作。我已将refresh设置为changeData,并尝试使用widget.refresh调用该函数。(代码的最后一行) 稍后,我将尝试实现一些内容:) 一个完全不同的问题,但仍然是关于颤振的:关于一节课可以有多少行?有没有“嘿,伙计,太多了”Function 浮动操作按钮赢得';不要叫刷新,function,button,flutter,stateful,Function,Button,Flutter,Stateful,我正在制作一个简单的数学应用程序(见下面的代码)。我现在的问题是为什么我的浮动操作按钮(刷新)不能工作。我已将refresh设置为changeData,并尝试使用widget.refresh调用该函数。(代码的最后一行) 稍后,我将尝试实现一些内容:) 一个完全不同的问题,但仍然是关于颤振的:关于一节课可以有多少行?有没有“嘿,伙计,太多了” 导入“包装:颤振/材料.省道”; 导入“dart:math”; void main()=>runApp(MyHome()); 类MyHome扩展了无状态小
导入“包装:颤振/材料.省道”;
导入“dart:math”;
void main()=>runApp(MyHome());
类MyHome扩展了无状态小部件{
@凌驾
小部件构建(构建上下文){
返回材料PP(
标题:“简单数学”,
主题:主题数据(原始样本:颜色。红色),
首页:头等舱(),
);
}
}
类FirstClass扩展StatefulWidget{
@凌驾
_FirstClassState createState();
}
类_FirstClassState扩展了状态{
最终随机=随机();
整数a,b,和;
字符串输出;
void changeData(字符串按钮名称){
设置状态(){
a=随机。nextInt(10);
b=随机。nextInt(10);
如果(buttonName=='+'){
总和=a+b;
输出='$a+$b=';
}如果(buttonName='-'),则为else{
如果(a>=b){
总和=a-b;
输出='$a-$b=';
}否则,如果(b>a){
//这里的和不能为负
sum=b-a;
输出='$b-$a=';
}
}
打印(sum.toString());
Navigator.of(context.popintil)(ModalRoute.withName('/');
导航器.of(上下文).push(MaterialPageRoute(
生成器:(上下文)=>SecondClass(
sum:sum,
刷新:更改数据,
输出:输出,
)));
});
}
@凌驾
小部件构建(构建上下文){
返回脚手架(
appBar:appBar(
标题:文本(“第一屏”),
),
正文:中(
子:列(
mainAxisSize:mainAxisSize.min,
儿童:[
RaisedButton(子项:文本(“+”),ON按下:()=>
changeData(“+”),
RaisedButton(子项:文本('-')),ON按下:()=>changeData('-
')),
],
),
),
);
}
}
类SecondClass扩展StatefulWidget{
最终整数和;
最终字符串输出;
最终功能刷新;
第二类({this.sum,this.refresh,this.output});
@凌驾
_SecondClassState createState()=>\u SecondClassState();
}
类_SecondClassState扩展状态{
字符串输入应答;
字符串输出=”;
@凌驾
void initState(){
super.initState();
}
小部件构建(构建上下文){
返回脚手架(
appBar:appBar(
标题:文本(“第二屏”),
),
正文:中(
子:容器(
子:列(
mainAxisAlignment:mainAxisAlignment.center,
儿童:[
划船(
mainAxisAlignment:mainAxisAlignment.center,
儿童:[
文本(widget.output),
容器(
宽度:50.0,
孩子:TextField(
键盘类型:TextInputType.number,
一旦更改:(val){
enterAnswer=val;
},
)),
],
),
升起的按钮(
已按下:(){
如果(输入答案。isNotEmpty){
if(enterAnswer==widget.sum.toString()){
设置状态(){
输出='正确!';
});
}否则{
设置状态(){
输出='对不起,我的回答';
});
}
}否则{
设置状态(){
输出='您必须输入一个值';
});
}
},
子项:文本(“检查答案”),
),
文本(输出),
浮动操作按钮(
子:图标(Icons.refresh),
已按下:(){
widget.refresh();
})
],
),
),
),
);
}
}
在代码中,您需要将参数作为-void changeData(字符串按钮名称)
将字符串作为参数传递
工作代码:
FloatingActionButton(
child: Icon(Icons.refresh),
onPressed: () {
widget.refresh('+');
})
更新:
正确的方法是同时传递按钮名称字符串
import 'package:flutter/material.dart';
import 'dart:math';
void main() => runApp(MyHome());
class MyHome extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'simple math',
theme: ThemeData(primarySwatch: Colors.red),
home: FirstClass(),
);
}
}
class FirstClass extends StatefulWidget {
@override
_FirstClassState createState() => _FirstClassState();
}
class _FirstClassState extends State<FirstClass> {
final random = Random();
int a, b, sum;
String output;
void changeData(String buttonName) {
setState(() {
a = random.nextInt(10);
b = random.nextInt(10);
if (buttonName == '+') {
sum = a + b;
output = '$a + $b = ';
} else if (buttonName == '-') {
if (a >= b) {
sum = a - b;
output = '$a - $b = ';
} else if (b > a) {
//sum cannot be negative here
sum = b - a;
output = '$b - $a = ';
}
}
print(sum.toString());
Navigator.of(context).popUntil(ModalRoute.withName('/'));
Navigator.of(context).push(MaterialPageRoute(
builder: (context) => SecondClass(
sum: sum,
refresh: changeData,
output: output,
buttonName: buttonName,
)));
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('First Screen'),
),
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
RaisedButton(child: Text('+'), onPressed: () => changeData('+')),
RaisedButton(child: Text('-'), onPressed: () => changeData('-')),
],
),
),
);
}
}
class SecondClass extends StatefulWidget {
final int sum;
final String output;
final String buttonName;
final Function refresh;
SecondClass({this.sum, this.refresh, this.output, this.buttonName});
@override
_SecondClassState createState() => _SecondClassState();
}
class _SecondClassState extends State<SecondClass> {
String enterAnswer;
String output = "";
@override
void initState() {
super.initState();
}
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Second Screen'),
),
body: Center(
child: Container(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(widget.output),
Container(
width: 50.0,
child: TextField(
keyboardType: TextInputType.number,
onChanged: (val) {
enterAnswer = val;
},
)),
],
),
RaisedButton(
onPressed: () {
if (enterAnswer.isNotEmpty) {
if (enterAnswer == widget.sum.toString()) {
setState(() {
output = 'Correct!';
});
} else {
setState(() {
output = 'Sorry, Worong answer';
});
}
} else {
setState(() {
output = 'You must enter a value';
});
}
},
child: Text('Check Answer'),
),
Text(output),
FloatingActionButton(
child: Icon(Icons.refresh),
onPressed: () {
widget.refresh(widget.buttonName);
})
],
),
),
),
);
}
}
导入“包装:颤振/材料.省道”;
导入“dart:math”;
void main()=>runApp(MyHome());
类MyHome扩展了无状态小部件{
@凌驾
小部件构建(构建上下文){
返回材料PP(
标题:“简单数学”,
主题:主题数据(原始样本:颜色。红色),
首页:头等舱(),
);
}
}
类FirstClass扩展StatefulWidget{
@凌驾
_FirstClassState createState();
}
类_FirstClassState扩展了状态{
最终随机=随机();
整数a,b,和;
字符串输出;
void changeData(字符串按钮名称){
设置状态(){
a=随机。nextInt(10);
b=随机。nextInt(10);
如果(buttonName=='+'){
总和=a+b;
输出='$a+$b=';
}如果(buttonName='-'),则为else{
如果(a>=b){
总和=a-b;
输出='$a-$b=';
}否则,如果(b>a){
//这里的和不能为负
sum=b-a;
输出='$b-$a=';
}
}
打印(sum.toString());
Navigator.of(context.popintil)(ModalRoute.withName('/');
导航器.of(上下文).push(MaterialPageRoute(
生成器:(上下文)=>SecondClass(
sum:sum,
刷新:更改数据,
输出:输出,
buttonName:buttonName,
)
import 'package:flutter/material.dart';
import 'dart:math';
void main() => runApp(MyHome());
class MyHome extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'simple math',
theme: ThemeData(primarySwatch: Colors.red),
home: FirstClass(),
);
}
}
class FirstClass extends StatefulWidget {
@override
_FirstClassState createState() => _FirstClassState();
}
class _FirstClassState extends State<FirstClass> {
final random = Random();
int a, b, sum;
String output;
void changeData(String buttonName) {
setState(() {
a = random.nextInt(10);
b = random.nextInt(10);
if (buttonName == '+') {
sum = a + b;
output = '$a + $b = ';
} else if (buttonName == '-') {
if (a >= b) {
sum = a - b;
output = '$a - $b = ';
} else if (b > a) {
//sum cannot be negative here
sum = b - a;
output = '$b - $a = ';
}
}
print(sum.toString());
Navigator.of(context).popUntil(ModalRoute.withName('/'));
Navigator.of(context).push(MaterialPageRoute(
builder: (context) => SecondClass(
sum: sum,
refresh: changeData,
output: output,
buttonName: buttonName,
)));
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('First Screen'),
),
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
RaisedButton(child: Text('+'), onPressed: () => changeData('+')),
RaisedButton(child: Text('-'), onPressed: () => changeData('-')),
],
),
),
);
}
}
class SecondClass extends StatefulWidget {
final int sum;
final String output;
final String buttonName;
final Function refresh;
SecondClass({this.sum, this.refresh, this.output, this.buttonName});
@override
_SecondClassState createState() => _SecondClassState();
}
class _SecondClassState extends State<SecondClass> {
String enterAnswer;
String output = "";
@override
void initState() {
super.initState();
}
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Second Screen'),
),
body: Center(
child: Container(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(widget.output),
Container(
width: 50.0,
child: TextField(
keyboardType: TextInputType.number,
onChanged: (val) {
enterAnswer = val;
},
)),
],
),
RaisedButton(
onPressed: () {
if (enterAnswer.isNotEmpty) {
if (enterAnswer == widget.sum.toString()) {
setState(() {
output = 'Correct!';
});
} else {
setState(() {
output = 'Sorry, Worong answer';
});
}
} else {
setState(() {
output = 'You must enter a value';
});
}
},
child: Text('Check Answer'),
),
Text(output),
FloatingActionButton(
child: Icon(Icons.refresh),
onPressed: () {
widget.refresh(widget.buttonName);
})
],
),
),
),
);
}
}