Examples of Async-Await

PHOTO

Fri Sep 11 2020 07:50:15 GMT+0000 (UTC)

Saved by @darshjain #dart

//I think your understanding of Promises and async/await is not correct.
//When you make a function async, the await keyword before a promise make sure
//that code execution will pause until the promise fulfilled or rejected. 
//Your code can be simplified:

var currentPromise;

async function asyncFunc(promise){
    // Do some code here
    return await promise;
}

function anotherFunction(){
    asyncFunc(currentPromise);
}
//When we are calling return await promise, the execution engine waits in a
//non-blocking way until the promise fulfilled or rejected, and then it returns 
//the output to the anotherFunction function.

Examples for StackOverflow

Save snippets that work from anywhere online with our extensions

Available in the Chrome Web Store

Get Firefox Add-on

Get VS Code extension

Comments

More like this

Asyn-Await

@darshjain

Examples of Async-Await

#dart #flutter #layouts

How to make height of all widgets inside Row equal the tallest widget

Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(title: Text('IntrinsicWidth')),
    body: Center(
      child: IntrinsicHeight(
        child: Row(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: <Widget>[
            RaisedButton(
              onPressed: () {},
              child: Text('Short'),
            ),
            RaisedButton(
              onPressed: () {},
              child: Text('A bit Longer'),
            ),
            RaisedButton(
              onPressed: () {},
              child: Text('The Longest text button'),
            ),
          ],
        ),
      ),
    ),
  );
}

How to sort/order a list by date in dart/flutter? - Stack Overflow

products.sort((a,b) => a.compareTo(b));

How do I upgrade an existing Flutter app? - Stack Overflow

sdk: ">=2.12.0 <3.0.0"


Then follow the steps:

Run flutter upgrade in the terminal to upgrade Flutter
Run dart migrate to run the dart migration tool.
Solve all errors which the migration tool shows.
Run flutter pub outdated --mode=null-safety to print all outdated packages.
Run flutter pub upgrade --null-safety to upgrade all packages automatically.
Check the code for errors and solve them (Very important).
Run dart migrate again and it should now be successful. Follow the link to checkout the proposed changes.
Press the "Apply Migration" button.
Check the code for errors again and fix them.

#android #dart #flutter #ios #helloworld

All the code you need to run Hello World in Flutter using a Stateless widget

import 'package:flutter/material.dart';

void main() {
  runApp(
    new MaterialApp(
      title: 'Hello World App',
      home: new myApp(),
    )
  );
}

class myApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text('Hello World App'),
      ),
      body: new Center(
        child: new Text(
          'Hello, world!'
        ),
      ),
    );
  }
}

How to remove debug banner in flutter on android emulator? - Stack Overflow

MaterialApp(
 debugShowCheckedModeBanner: false
)

Flutter Layout Cheat Sheet. Do you need simple layout samples for… | by Tomek Polański | Flutter Community | Medium

Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(title: Text('IntrinsicWidth')),
    body: Center(
      child: IntrinsicWidth(
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: <Widget>[
            RaisedButton(
              onPressed: () {},
              child: Text('Short'),
            ),
            RaisedButton(
              onPressed: () {},
              child: Text('A bit Longer'),
            ),
            RaisedButton(
              onPressed: () {},
              child: Text('The Longest text button'),
            ),
          ],
        ),
      ),
    ),
  );
}

android - Flutter Error - FileSystemException: Creation failed, path = 'storage/emulated/0/myDir' (OS Error: Operation not permitted, errno = 1) - Stack Overflow

<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"
        tools:ignore="ScopedStorage" />

Capitalize the first letter of a String

String capitalize(String s) {
  if (s == null || s.isEmpty) {
    return s;
  }
  return s.length < 1 ? s.toUpperCase() : s[0].toUpperCase() + s.substring(1);
}

#dart #flutter #howto

How to decorate text stroke in Flutter

Text("Border test",
    style: TextStyle(
      inherit: true,
      fontSize: 48.0,
      color: Colors.pink,
      shadows: [
        Shadow( // bottomLeft
          offset: Offset(-1.5, -1.5),
          color: Colors.white
        ),
        Shadow( // bottomRight
          offset: Offset(1.5, -1.5),
          color: Colors.white
        ),
        Shadow( // topRight
          offset: Offset(1.5, 1.5),
          color: Colors.white
        ),
        Shadow( // topLeft
          offset: Offset(-1.5, 1.5),
          color: Colors.white
        ),
      ]
    ),
);

#dart #flutter #layout

How to make width of all widgets inside Column equal the widest widget

Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(title: Text('IntrinsicWidth')),
    body: Center(
      child: IntrinsicWidth(
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: <Widget>[
            RaisedButton(
              onPressed: () {},
              child: Text('Short'),
            ),
            RaisedButton(
              onPressed: () {},
              child: Text('A bit Longer'),
            ),
            RaisedButton(
              onPressed: () {},
              child: Text('The Longest text button'),
            ),
          ],
        ),
      ),
    ),
  );
}

timer - Flutter - Blinking button - Stack Overflow

  class MyBlinkingButton extends StatefulWidget {
    @override
    _MyBlinkingButtonState createState() => _MyBlinkingButtonState();
  }

  class _MyBlinkingButtonState extends State<MyBlinkingButton>
      with SingleTickerProviderStateMixin {
    AnimationController _animationController;

    @override
    void initState() {
      _animationController =
          new AnimationController(vsync: this, duration: Duration(seconds: 1));
      _animationController.repeat(reverse: true);
      super.initState();
    }

    @override
    Widget build(BuildContext context) {
      return FadeTransition(
        opacity: _animationController,
        child: MaterialButton(
          onPressed: () => null,
          child: Text("Text button"),
          color: Colors.green,
        ),
      );
    }

    @override
    void dispose() {
      _animationController.dispose();
      super.dispose();
    }
  }

Flutter Cheatsheet

https://github.com/Temidtech/Flutter-Cheat-Sheet/blob/master/README.md

Flutter container with overlay

                Container(
                  height: SizeConfig.safeBlockVertical * 24,
                  width: SizeConfig.safeBlockHorizontal * 45,
                  padding: EdgeInsets.only(
                      left: SizeConfig.safeBlockHorizontal * 5,
                      right: SizeConfig.safeBlockHorizontal * 4,
                      bottom: SizeConfig.safeBlockVertical * 2),
                  decoration: BoxDecoration(
                      borderRadius: BorderRadius.circular(20),
                      color: Colors.white,
                      gradient: RadialGradient(
                          focalRadius: 100,
                          radius: 1.5,
                          center: Alignment.bottomLeft,
                          colors: [
                            colorStyles["maslowGreen"]!.withOpacity(0.65),
                            colorStyles["maslowGreen"]!.withOpacity(0.65),
                          ],
                          stops: [
                            0.0,
                            1.0
                          ])),
                  child: _collectionName(),
                ),

Flutter - Container Decoration

Container(
                                child: Text(
                                  items[index].itemName,
                                  style: TextStyle(
                                      color: Colors.black, fontSize: 30),
                                  textAlign: TextAlign.center,
                                ), //Text
                                height: 40,
                                width: 400,
                                  decoration:
                               BoxDecoration(
                  border: Border.all(color: Colors.black38, width: 3),
                  borderRadius: BorderRadius.circular(20),
                  boxShadow: [
                    BoxShadow(
                      color: Colors.black.withOpacity(0.5),
                      spreadRadius: 5,
                      blurRadius: 5,
                      offset: Offset(0, 3), // changes position of shadow
                    ),
                  ],
                  color: Colors.white,
                  image: DecorationImage(
                    image: AssetImage(filterList[index].itemImg),
                    fit: BoxFit.contain,
                  ),
                ),

Checks if a string is an anagram of another string in Dart- isAnagram

bool isAnagram(String str1, String str2) {
  String normalize(String str) => (str
          .toLowerCase()
          .replaceAll(RegExp(r'[^a-z0-9]', caseSensitive: false), '')
          .split('')
            ..sort())
      .join('');
  return normalize(str1) == normalize(str2);
}

Browse more snippets >>