dart

问题 I have a ternary operator in my home_screen: CircleData2.dk1 == 0 ? Padding(child: Center(child: Container(height: 50, width: 50, color: Colors.pink,)), padding: EdgeInsets.all(40),) : Try2(id: 1, reload: reload,), I want when CircleData.dk1 not equals 0 (it starts off equaling 1) to drop the current object that's dragging (Try2 is a custom widget that is a draggable, I'll show it in a moment) and just replace it with the: Padding(child: Center(child: Container(height: 50, width: 50, color:

问题 I can disable the tooltip statically. But I want to disable tooltip dynamically when i click flatbutton.But Couldnt disable dynamically and i have no idea to do that. This is my code: import 'package:flutter/material.dart'; void main(){ runApp(MaterialApp(home: HelloWorld(),debugShowCheckedModeBanner: false,)); } class HelloWorld extends StatefulWidget { @override _HelloWorldState createState() => _HelloWorldState(); } class _HelloWorldState extends State<HelloWorld> { bool check = false;

问题 I have created canvas using RenderBox. class MyHomePage extends StatefulWidget { @override _MyHomePageState createState() => new _MyHomePageState(); } class _MyHomePageState extends State<MyHomePage> { @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar(), body: Column( children: <Widget>[ Container(color:Colors.yellow,height:50,child: Center(child: Text("Canvas"))), Expanded( child: PageView( children: <Widget>[ Container( color: Colors.red, child: CanvasWidget(),

问题 Everyone I'm using NFC plugin "nfc_in_flutter" in my flutter app but I'm facing "New Tag Scanned" issue in android build. Whenever I scan tag, First time, it works good but on second time automatically/bydefault "New Tag Scanned" activity open. Here is my code: Future<String> _nFCscan() async { String nfcdataString = ""; setState(() { _inAsyncCall = true; }); try { NDEFMessage message = await NFC .readNDEF(once: true, readerMode: NFCDispatchReaderMode()) .timeout(Duration(seconds: 10)) .first

问题 I am using Firebase and keep getting this annoying message when I click on the Sign Up button : flutter: 'package:firebase_auth_platform_interface/src/method_channel/method_channel_user_credential.dart': Failed assertion: line 14 pos 16: 'data != null': is not true. The code works fine. The app is built and run successfully. This happens when I enter my phone, email and password and click on the signup button. My code is: import 'package:flutter/material.dart'; import 'package:firebase_auth

问题 Why in dart we have String not string Other types are in lower case int not Int double not Double 回答1: The reason for the naming was to make Dart more familiar to people coming from Java (or C#, but mostly Java). That's why int , double , bool and void are lower-case and String is capitalized, because that's what they were in Java (although boolean was considered too damn long). The num type got looped in too, because it's so closely tied to int and double , and dynamic was lower case to mark

问题 There are many versions of implementation of BLoC pattern. One of them is flutter_bloc by Felix Angelov. On one of the social medias I came across of the statement that flutter_bloc is not a good choice for the project and another BLoC or another state management should be chosen instead . Actually it was a small standard project separated into layers:domain,application,infrastructure and presentation. Nothing special about it. So the guy who complained about the wrong choice was saying that

问题 I load an image on my flutter app like this: Image.asset(imageFilePath, fit: BoxFit.cover) When I run the app on the emulator on the first run I get the following exception: I/flutter ( 7194): ══╡ EXCEPTION CAUGHT BY IMAGE RESOURCE SERVICE ╞════════════════════════════════════════════════════ I/flutter ( 7194): The following assertion was thrown resolving an image codec: I/flutter ( 7194): Unable to load asset: /data/user/0/com.example.myapp/app_flutter/888cba5135c38f7d.jpg ... The image path

问题 I load an image on my flutter app like this: Image.asset(imageFilePath, fit: BoxFit.cover) When I run the app on the emulator on the first run I get the following exception: I/flutter ( 7194): ══╡ EXCEPTION CAUGHT BY IMAGE RESOURCE SERVICE ╞════════════════════════════════════════════════════ I/flutter ( 7194): The following assertion was thrown resolving an image codec: I/flutter ( 7194): Unable to load asset: /data/user/0/com.example.myapp/app_flutter/888cba5135c38f7d.jpg ... The image path

问题 I have looked at this question on Stack Overflow Flutter getter isn't specified for the class, when it is specified. And I still cannot understand why my class Practice does not have access to the variable _text which is accessed from an element in the List with type TagColumn . class Practice extends StatefulWidget { @override _PracticeState createState() => _PracticeState(); } class _PracticeState extends State<Practice>{ int count = 0; @override Widget build(BuildContext context){ List