我正在嘗試為我的顫振應用程式制作一個重繪 按鈕（然后是一個下拉手勢）。我希望如果我按下重繪 按鈕，則呼叫 a 方法，并從網路服務器中提取資料，并且重新構建布局。
到目前為止，這是我的代碼：我的 main.dart：
class MyHomePageState extends State<MyHomePage> {
final GetWebsites _getWebsites = GetWebsites();
@override
void initState() {
refresh();
super.initState();
}
@override
Widget build(BuildContext context) {
return MaterialApp(
home: getSites(),
);
}
//Get sites => Document, store them in a Document list
Widget getSites() {
return FutureBuilder<List<html.Document>>(
//gets Dates of each date in other class and puts it in an List -> snapshot
future: _getWebsites.getWebsite(),
builder: (BuildContext context, AsyncSnapshot<List<html.Document>> snapshot) {
//Cases for Connections
switch(snapshot.connectionState) {
case ConnectionState.active:
case ConnectionState.waiting:
return const Center(
//TODO: Make better loading screen
child: RefreshProgressIndicator(),
);
case ConnectionState.none:
return const Center(
child: Text("Keine Verbindung"),
);
case ConnectionState.done:
if (snapshot.hasError) {
return const Center(
child: Text('Fehler'),
);
}
//create tabs
return buildrefresh(snapshot);
}
},
);
}
Widget buildrefresh(AsyncSnapshot<List<html.Document>> snapshot) {
return RefreshIndicator(
onRefresh: () {
return refresh();
},
child: rowortabbedLayout(snapshot),
);
}
Widget rowortabbedLayout(AsyncSnapshot<List<html.Document>> snapshot) {
if(Settings.getValue<bool>("keyrowortabbed", true)){
return TabbedLayout().createTabbedLayout(snapshot, context);
}else{
return RowLayout().createRowLayout(snapshot, context);
}
}
Future<void> refresh() async {
setState((){
FutureBuilder<List<html.Document>>(
//gets Dates of each date in other class and puts it in an List -> snapshot
future: _getWebsites.getWebsite(),
builder: (BuildContext context, AsyncSnapshot<List<html.Document>> snapshot) {
//Cases for Connections
switch(snapshot.connectionState) {
case ConnectionState.active:
case ConnectionState.waiting:
return const Center(
child: RefreshProgressIndicator(),
);
case ConnectionState.none:
return const Center(
child: Text("Keine Verbindung"),
);
case ConnectionState.done:
if (snapshot.hasError) {
return const Center(
child: Text('Fehler'),
);
}
//create tabs
return buildrefresh(snapshot);
}
},
);
});
print("Do something!");
}
Future<void> setstaterefresh() async {
setState((){});
print("Do something!");
}
}
對于選項卡式布局（也有行布局，但我稍后會這樣做）
class TabbedLayout{
final SiteParser _getSiteData = SiteParser();
Widget createTabbedLayout(AsyncSnapshot<List<html.Document>> snapshot, BuildContext context){
return buildrevresh(snapshot,context);
}
Widget buildrevresh(AsyncSnapshot<List<html.Document>> snapshot, BuildContext context) {
return RefreshIndicator(
onRefresh: () {
return MyHomePageState().setstaterefresh();
},
child: tabcontroller(snapshot,context),
);
}
Widget tabcontroller(AsyncSnapshot<List<html.Document>> snapshot, BuildContext context) {
return DefaultTabController(length: snapshot.data!.length,
child: Scaffold(
appBar: AppBar(
actions: <Widget> [
IconButton(
onPressed: () {
Navigator.push(context, MaterialPageRoute(builder: (context) => const MySettings()),
);
},
icon: const Icon(Icons.settings),
),
//Refresh Button:
IconButton(
icon: const Icon(Icons.refresh),
onPressed: () {
MyHomePageState().refresh();
},
),
],
bottom: TabBar(
isScrollable: true,
tabs:
//Tab names
tabBarMaker(snapshot),
),
title: const Text("Vertretungsplan")
),
body:
TabBarView(
children:
tabMaker(snapshot),
physics: const BouncingScrollPhysics(),
),
),
);
}
List<Widget> tabBarMaker(AsyncSnapshot<List<html.Document>> snapshot) {
List<Tab> tabs = [];
for(int x = 0; x<snapshot.data!.length; x ) {
tabs.add(Tab(text: snapshot.data![x].querySelector('h1.list-table-caption')!.text
.toString()));
}
return tabs;
}
//Create Tabs with contetnt for each site
List<Widget> tabMaker(AsyncSnapshot<List<html.Document>> snapshot) {
List<Widget> tabwidgets = [];
for(int x = 0; x<snapshot.data!.length; x ) {
tabwidgets.add(_buildDay(snapshot.data![x]));
}
return tabwidgets;
}
//Widget to create Tabs of each day and their contents
//Get Contents of a day
Widget _buildDay(html.Document site) {
List<tage> days = _getSiteData.getData(site);
return ListView.builder(
padding: const EdgeInsets.all(10),
itemCount: days.length,
physics: const BouncingScrollPhysics(),
itemBuilder: (context, index) {
//Build cards for each content
return MyThemes().buildCard(days[index]);
},
);
}
}
當我嘗試這個時，我收到此錯誤：
E/flutter (13792): [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: setState() called in constructor: MyHomePageState#a8b0c(lifecycle state: created, no widget, not mounted)
E/flutter (13792): This happens when you call setState() on a State object for a widget that hasn't been inserted into the widget tree yet. It is not necessary to call setState() in the constructor, since the state is already assumed to be dirty when it is initially created.
E/flutter (13792): #0 State.setState.<anonymous closure> (package:flutter/src/widgets/framework.dart:1076:9)
E/flutter (13792): #1 State.setState (package:flutter/src/widgets/framework.dart:1087:6)
E/flutter (13792): #2 MyHomePageState.refresh (package:khsplan/main.dart:140:5)
E/flutter (13792): #3 TabbedLayout.tabcontroller.<anonymous closure> (package:khsplan/Vplan/tabbedlayout.dart:42:37)
E/flutter (13792): #4 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:989:21)
E/flutter (13792): #5 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:193:24)
E/flutter (13792): #6 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:608:11)
E/flutter (13792): #7 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:296:5)
E/flutter (13792): #8 BaseTapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:230:7)
E/flutter (13792): #9 PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:558:9)
E/flutter (13792): #10 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:94:12)
E/flutter (13792): #11 PointerRouter._dispatchEventToRoutes.<anonymous closure> (package:flutter/src/gestures/pointer_router.dart:139:9)
E/flutter (13792): #12 _LinkedHashMapMixin.forEach (dart:collection-patch/compact_hash.dart:400:8)
E/flutter (13792): #13 PointerRouter._dispatchEventToRoutes (package:flutter/src/gestures/pointer_router.dart:137:18)
E/flutter (13792): #14 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:123:7)
E/flutter (13792): #15 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:440:19)
E/flutter (13792): #16 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:420:22)
E/flutter (13792): #17 RendererBinding.dispatchEvent (package:flutter/src/rendering/binding.dart:278:11)
E/flutter (13792): #18 GestureBinding._handlePointerEventImmediately (package:flutter/src/gestures/binding.dart:374:7)
E/flutter (13792): #19 GestureBinding.handlePointerEvent (package:flutter/src/gestures/binding.dart:338:5)
E/flutter (13792): #20 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:296:7)
E/flutter (13792): #21 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:279:7)
E/flutter (13792): #22 _rootRunUnary (dart:async/zone.dart:1444:13)
E/flutter (13792): #23 _CustomZone.runUnary (dart:async/zone.dart:1335:19)
E/flutter (13792): #24 _CustomZone.runUnaryGuarded (dart:async/zone.dart:1244:7)
E/flutter (13792): #25 _invoke1 (dart:ui/hooks.dart:185:10)
E/flutter (13792): #26 PlatformDispatcher._dispatchPointerDataPacket (dart:ui/platform_dispatcher.dart:293:7)
E/flutter (13792): #27 _dispatchPointerDataPacket (dart:ui/hooks.dart:98:31)
E/flutter (13792):
uj5u.com熱心網友回復：
將您的 initState() 方法更改為以下內容：
@override
void initState() {
super.initState();
WidgetsBinding.instance.addPostFrameCallback((_) {
refresh();
});
}
這樣，您的 refresh() 函式將在您的小部件完成其第一次構建后執行。
uj5u.com熱心網友回復：
只做一個重繪 功能
無效重繪 （）{ setState（{
}); }
并在您按下的按鈕中使用它。
轉載請註明出處，本文鏈接：https://www.uj5u.com/yidong/400728.html
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