Most voted "flutter" questions
Flutter is a mobile application development SDK created by Google.
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answers97
viewsHow do I know if a package is dev_dependencies or dependencies?
Taking as the example of this two packages: freezed and freezed_annotation, the installation instruction on the site pub dev. is the same for both packages: However, on video showing how to use this…
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answers264
viewsInterface or instance of a Generic
Interface I wanted to use interface in Dart, but after a lot of searching, discover that there is not, so I did it this way, I created an abstract class: abstract class IModel { String _uid;…
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answers88
viewsClause error Where SQLITE
Hi, I have a small problem in the following method: Future<List> getAllTarefasMediaPrioridade(String status) async{ Database dbTarefas = await db; List<Tarefas>…
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answers28
viewsCreate a groupedList with map
Hello, I’m new to flutter and I’m trying to create a list with grouping using the map, but I’m not getting... I saw that I can use the Groupedlistview, but how to map it? GroupedListView( elements:…
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answers36
viewsTrigger after Insert SQLITE
Hello, I have a table of activities (for Deposit or Withdrawal of a piggy bank app) is inserted ID (PK automatica), value (double) Day (Text) type (can be 0 - for deposits / 1 - withdrawals) and…
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answers34
viewsProblem using System with Where firebase
Hello, I’m trying to filter orders by the current date, but when I try to use Where in the firebase’s Collection, my Listen simply stops working. Sending no new update to the list. In a totally…
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answer115
viewsHow to remove double quotes from the beginning and end of a Dart variable?
Speak devs, all right? I am unable to remove double quotes from the beginning and end of a Dart variable. I post to my Web API and receive a JWT Object. I only need the value of the object, without…
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answer39
viewsMethod into classless files. Flutter
Guys I came across a code inside a flutter file (Dart) that left me with some doubts, is a classless Dart file with only one method declared. I tried to look at the documentation but I guess I…
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answer54
viewsFlutter: snapshot.data does not load Json value
I’m creating a code for a Udemy course that I can’t get the answer to code that works on the teacher’s machine. I tried to change the versions, but apparently, the error is in the request response…
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answer1874
viewsUse of getter and Setter on Dart
I can not understand the real need to use the Get/Set for the case below, which, even if I leave the variable commotion private, I could still modify it by using methods. class casa { int comodos =…
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answer714
viewsExpansion Tile and Listview
I’m trying to create this layout for an app, I used an Expansion Tile inside a Card and a listview below, but when I open the expansionTile, if hitting the bottom of the screen happened that and if…
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answer524
viewsDatepicker problem in Flutter
I have a problem when it comes time to set the state of DatePicker in Flutter. The same returns me the error: Another Exception was thrown: Failed assertion: Boolean Expression must not be null…
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answer9962
viewsFormat Number in Flutter
I have the following function that calculates and saves 2 data in my database, but I want to format kwhAparelho and totalAparelho in a way that does not cause periodic tithes and preferably this way…
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answers1042
viewsHow to check if a file already exists in a mobile directory in Flutter?
I have a method to check certain files. pdf exist in the app folder, I used path_provider to get the path, how do I check if the file exists in the directory? Future<void> checkFile() async{…
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answers450
viewsHow does the Flutter (Framework, SDK, Dart) architecture work?
In Flutter studies I often get confused, when creating an UI, after all I am using Dart/Flutter (framework) or both? Ex: children: widget.products.map((Product product) { return ShoppingListItem(…
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answer624
viewsAPI request returns empty in mapped class
I have a problem trying to return the answer of a api in my class. When I try to run my list returns null instead of the api data My class Photo class Foto { final int AlbumId; final int Id; final…
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answers40
viewsFlutter APP - How to read emails from user App
I am trying to build an app with flutter that asks for the users permission to read their email. I know that I need to use the Permission Services but the Thing is, after the user accepts the email…
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answer361
viewsHow to access Drawermenu in the multi-screen flutter?
I’m Getting an Application in Flutter, added to my HomePage one DrawerMenu, It works well, but when I access another page, I wish the menu could be opened from anyone. I saw some examples creating…
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answer175
viewsConcept of delegate in Flutter
I saw that there is no support for delegate in flutter, is there any way to implement something like that? I believe that a callback work, I tried to formulate some examples but I’m not able to…
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answers2133
viewsHow to open another screen in Flutter?
I have an app for QRCODE scanner and I have the following check: // Executa função para o scanner Future _scan() async { String barcode = await scanner.scan(); if (barcode.contains("cx-")) { //…
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answer1013
viewsTake Textformfield value in double
How can I get the value of a Textformfield in double? I’ve created a Texteditingcontroller, var controller = new TextEditingController(); but the controller.text comes in string and I can’t get it…
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answer595
viewsHow to change the status bar text color with Cupertinonavigationbar
I’m trying to put the text of the iPhone color status bar in white color I already tried to put in main the Systemuioverlaystyle, with the statusBarColor and the light brightness but it didn’t…
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answers843
viewsSerialize JSON List in Flutter
I have an application in Fluter, and I have a return Json with List. I wanted to serialize the List to display it at a certain point, but I couldn’t find a way to do that. An example of my code:…
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answer1630
viewsThe method 'validate' was called on null. Receiver: null Tried Calling: validate()
In the code created in VS Code I am trying to implement the validate when receiving the information of the 02 values fields, for some reason the code is correct more present in DEBUG CONSOLE. Follow…
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answer2339
viewsFlutter - login screen
Good morning, I am creating a login screen with email authentication and password by firebase. Some layout rendering errors are happening. this is the code: import 'package:flutter/material.dart';…
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answer118
viewsFlutter is compiling forever (Not over)
I start after an update on Archlinux. I have uninstalled android studio and flutter and nothing. When I try on a Windows machine the project is compiled normally flutter doctor Doctor summary (to…
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answers482
viewsWhen is it recommended to Initialize a final property in the Class constructor?
The example below is a summary of the original (Bringing it all Together) found on the official Flutter page. On the first call, the class Cart is initialized by the constructor and in the second…
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answers213
viewsConcatenate Listview into Flutter
I’m trying to display a received list on Json, but I need to concatenate it for better visualization... First case - No concatenation Text(promocoes[index].descrprod) Second case - With…
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answers143
viewsError starting a Flutter app on Physical Iphone
I’m trying to run an app written in Flutter on physical iPhone, when I run the command flutter run deploy is started, but it carries infinitely. When I run via x-code the error below is presented…
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answer158
viewsGoogle Maps and Websocket Flutter
All right, come on... I’m developing an application using flutter (I’m new to the Dart language), so I need my application to update the markers of maps periodically along with Websocket, but when…
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answer155
viewsWhat does the * of the reserved words Sync*, async*, Yield* mean?
What does the * of reserved words Sync*, async*, Yield*mean? What’s the difference between them and their similar Sync, async and Yield?
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answers146
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answers455
viewsError executing a Flutter command
To test whether the flutter was correctly installed on my Linux machine I wrote in bash the following command : flutter doctor and received the following return message : zsh: command not found:…
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answer1044
viewsHow to generate, encode and encrypt random string in Flutter
I need to generate a 32byte code and encode for Base64, then Sha256 and Base64 again But apparently this code has something wrong and I can’t understand what it is var _random = Random.secure(); var…
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answer855
viewsDart/Flutter error: 'context != null': is not true
I’m trying to apply a dialog alert every time the item is duplicated but when I do the test it ends up giving this error, someone has some hint how to fix it ? void SalvarMensagem() async { //…
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answers40
viewsProblem with android studio
I’m developing in flutter, I can open android studio normally, I can even open the emulator too, but when I run the app in this open emulator android studio locks the whole computer and nothing…
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answers687
viewsHow to pick up text from a multi-line textfield in a list with one item per line
I wonder if you have any way to take a text from a textfield and turn it into a list. Text with an item on each line. To B C D List = [learns A', learns B', learns C', learns'] I tried to use one…
flutterasked 4 years, 7 months ago Fernando Foster 121 -
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answers78
viewsIs there any form of app review in flutter for android that is internal, like iOS?
From what I saw, on Flutter there is no kind of review within the app for Android. I looked in other places and saw that for native there is this possibility, to ask for a review and basically what…
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answer166
viewsIgnore column alignment in flutter
I’m trying to put a column inside another column, but I wonder if there’s any way to ignore the first alignment, as in the code below: class Login extends StatelessWidget { @override Widget…
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answers560
viewsCheck Empty Fluttter async return
How can I check if a return async of a particular sqlite is empty? I need to check if the "resultReceita" is null before displaying it in the widget. I tried with an if however, I did not succeed.…
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answer100
viewsWhat is the meaning of the operator ":" after a Builder on Dart?
I’m trying to understand and adapt a code. I’d like to know what this syntax means: EditMyModelScreen(MyModel p) : editing = p != null, mymodel = p != null ? p.clone() : MyModel(); In particular, I…
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answer112
viewsHow to condition the display of a Widget list?
I tried to use a if to condition the display of a list of Widgets: children: <Widget>[ if (condicao == true) { Widget(), Widget(), } ], The element type Set < Widget > can’t be Assigned…
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answer181
viewsWhat are the differences between BLOC x Cubit?
BLOC and Cubit are part of the same package (Bloc) and use the same standard (Bloc - Design Pattern Business Logic Component) which helps to separate the presentation layer from the business rule.…
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answers19
viewsFlutter - Split Sting
Good morning, I am beginner in flutter and I have this login screen just below in the image. as you can see has a String which would be the serial number of the device that occupied all my screen…
flutterasked 4 years, 3 months ago Victor Padovan 21 -
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answer52
viewsNULL value before incrementing
I am passing values from one screen to another, by clicking a button on the home screen send the data to my profile. But if I do not click this button and go to my profile screen the fields…
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answer41
viewsIs there any way to display a component only if there is data in the json file to populate it?
I’m doing a quiz app and it turns out that some questions have 5 and others have only 4 alternatives. In the tutorial I followed it creates 4 choicebutton. I, who am very innocent, added a fifth,…
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answer350
viewsAdd keyboard when using if in Textformfield in Flutter
I am with a plugin to select the country code and a TextFormField to enter the email/mobile. I have a variable to display or not this CountryCode. The problem is that when typing a number in the…
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answers302
viewsError: type 'Playlist' is not a subtype of type 'Items'
Excerpt from the Model code: int numero; String localEntrega; String dataHora; String formaPagamento; List<Itens> itens; ListarPedido( {this.numero, this.localEntrega, this.dataHora,…
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answers88
viewsFLUTTER ERROR The method 'to do Login' was called on null
Hello, whenever I call some element of my Provider, I get that error that this null import 'package:controlsport_app_ecommerce/helpers/validator.dart'; import…
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answer184
viewsFlutter Mobx+Modular Data Not Loaded
Opa I’m using mobx+modular in an app, but I’m having a problem, which I think should be a simple mistake my. I have a Controller where I want to save the seller and default customer to always be…