Flutter 扑动未来<;布尔>;vs布尔型
我的颤振项目有一个utility.dart文件和一个main.dart文件。我调用了main.dart文件中的函数,但它有问题。它总是显示“OK”,我认为问题在于实用程序类checkConnection()返回一个未来的bool类型 main.dart:Flutter 扑动未来<;布尔>;vs布尔型,flutter,future,Flutter,Future,我的颤振项目有一个utility.dart文件和一个main.dart文件。我调用了main.dart文件中的函数,但它有问题。它总是显示“OK”,我认为问题在于实用程序类checkConnection()返回一个未来的bool类型 main.dart: if (Utility.checkConnection()==false) { Utility.showAlert(context, "internet needed"); } else { Utility.showAlert(cont
if (Utility.checkConnection()==false) {
Utility.showAlert(context, "internet needed");
} else {
Utility.showAlert(context, "OK");
}
utility.dart:
import 'package:flutter/material.dart';
import 'package:connectivity/connectivity.dart';
import 'dart:async';
class Utility {
static Future<bool> checkConnection() async{
ConnectivityResult connectivityResult = await (new Connectivity().checkConnectivity());
debugPrint(connectivityResult.toString());
if ((connectivityResult == ConnectivityResult.mobile) || (connectivityResult == ConnectivityResult.wifi)){
return true;
} else {
return false;
}
}
static void showAlert(BuildContext context, String text) {
var alert = new AlertDialog(
content: Container(
child: Row(
children: <Widget>[Text(text)],
),
),
actions: <Widget>[
new FlatButton(
onPressed: () => Navigator.pop(context),
child: Text(
"OK",
style: TextStyle(color: Colors.blue),
))
],
);
showDialog(
context: context,
builder: (_) {
return alert;
});
}
}
导入“包装:颤振/材料.省道”;
导入“package:connectivity/connectivity.dart”;
导入“dart:async”;
类效用{
静态未来checkConnection()异步{
ConnectivityResult ConnectivityResult=await(新建连接().checkConnectivity());
debugPrint(connectivityResult.toString());
if((connectivityResult==connectivityResult.mobile)| |(connectivityResult==connectivityResult.wifi)){
返回true;
}否则{
返回false;
}
}
静态void showAlert(BuildContext上下文、字符串文本){
var alert=新建警报对话框(
内容:容器(
孩子:排(
儿童:[文本(文本)],
),
),
行动:[
新扁平按钮(
onPressed:()=>Navigator.pop(上下文),
子:文本(
“好的”,
样式:TextStyle(颜色:Colors.blue),
))
],
);
显示对话框(
上下文:上下文,
建筑商:(){
返回警报;
});
}
}
您需要从未来
中获取bool
。使用can然后阻塞
或等待
带then块
_checkConnection() {
Utiliy.checkConnection().then((connectionResult) {
Utility.showAlert(context, connectionResult ? "OK": "internet needed");
})
}
等待
_checkConnection() async {
bool connectionResult = await Utiliy.checkConnection();
Utility.showAlert(context, connectionResult ? "OK": "internet needed");
}
有关更多详细信息,请参阅。在未来函数中,您必须返回未来结果,因此您需要更改以下结果的返回:
return true;
致:
返回Future.value(true);
因此,正确返回的完整函数是:
static Future<bool> checkConnection() async{
ConnectivityResult connectivityResult = await (new Connectivity().checkConnectivity());
debugPrint(connectivityResult.toString());
if ((connectivityResult == ConnectivityResult.mobile) || (connectivityResult == ConnectivityResult.wifi)){
return Future<bool>.value(true);
} else {
return Future<bool>.value(false);
}
}
static Future checkConnection()异步{
ConnectivityResult ConnectivityResult=await(新建连接().checkConnectivity());
debugPrint(connectivityResult.toString());
if((connectivityResult==connectivityResult.mobile)| |(connectivityResult==connectivityResult.wifi)){
返回未来值(true);
}否则{
返回Future.value(false);
}
}
static Future<bool> checkConnection() async{
ConnectivityResult connectivityResult = await (new Connectivity().checkConnectivity());
debugPrint(connectivityResult.toString());
if ((connectivityResult == ConnectivityResult.mobile) || (connectivityResult == ConnectivityResult.wifi)){
return Future<bool>.value(true);
} else {
return Future<bool>.value(false);
}
}