dart

Flutter: how to prevent device orientation changes and force portrait?

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Import package:flutter/services.dart, then Put the SystemChrome.setPreferredOrientations inside the Widget build() method. Example: class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { SystemChrome.setPreferredOrientations([ DeviceOrientation.portraitUp, DeviceOrientation.portraitDown, ]); return new MaterialApp(…); } } Update This solution mightn’t work for some IOS devices as mentioned in the updated flutter documentation on Oct 2019. They Advise to fixed the … Read more

List use of double dot (.) in dart?

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.. is known as cascade notation. It allows you to not repeat the same target if you want to call several methods on the same object. List list = []; list.add(color1); list.add(color2); list.add(color3); list.add(color4); // with cascade List list = []; list ..add(color1) ..add(color2) ..add(color3) ..add(color4);

How to use conditional statement within child attribute of a Flutter Widget (Center Widget)

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Actually you can use if/else and switch and any other statement inline in dart / flutter. Use an immediate anonymous function class StatmentExample extends StatelessWidget { Widget build(BuildContext context) { return Text((() { if(true){ return “tis true”;} return “anything but true”; })()); } } ie wrap your statements in a function (() { // your … Read more

Sizing elements to percentage of screen width/height

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This is a supplemental answer showing the implementation of a couple of the solutions mentioned. FractionallySizedBox If you have a single widget you can use a FractionallySizedBox widget to specify a percentage of the available space to fill. Here the green Container is set to fill 70% of the available width and 30% of the … Read more

Dart SDK is not configured

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I had the same problem after importing a flutter project from git. These are the steps to solve the problem. File->Settings->Language & Framework->Flutter Choose flutter SDK path: the first time we install flutter, we choose the location where the flutter should be installed. Choose this location. Click OK and the android studio will refresh. Carry … Read more

flutter doctor –android-licenses gives a java error

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Installing Android SDK Command-line tools from Android SDK Manager did the job for me. Open Tools > SDK Manager From the left choose, Appearance & Behavior > System Settings > Android SDK Select SDK Tools from the top menu Check Android SDK Command-line tools and click ‘apply’. Alternative to step #1: WINDOWS: File > Settings … Read more

How do I format a date with Dart?

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You can use the intl package (installer) to format dates. For en_US formats, it’s quite simple: import ‘package:intl/intl.dart’; main() { final DateTime now = DateTime.now(); final DateFormat formatter = DateFormat(‘yyyy-MM-dd’); final String formatted = formatter.format(now); print(formatted); // something like 2013-04-20 } There are many options for formatting. From the docs: ICU Name Skeleton ——– ——– … Read more

Scaffold.of() called with a context that does not contain a Scaffold

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This exception happens because you are using the context of the widget that instantiated Scaffold. Not the context of a child of Scaffold. You can solve this by just using a different context : Scaffold( appBar: AppBar( title: Text(‘SnackBar Playground’), ), body: Builder( builder: (context) => Center( child: RaisedButton( color: Colors.pink, textColor: Colors.white, onPressed: () … Read more

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