Flutter Dev

Flutter Dev


Null Safety in Dart - Introduction

Dart is becoming null safe. In this video, we’re going to introduce the concept and why it’s valuable. You’ll learn about the basics, including syntax.

As of the release of this video, in November 2020, Dart null safety is in beta. This means you are free to experiment with the feature but should not use it in production apps.

#dart #flutter #mobile-apps #programming #developer

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Null Safety in Dart - Introduction
Waldo  Rippin

Waldo Rippin


Dart Null-safety and How It Affects Flutter

Randal talks about Dart “Non-Null-By-Default”-safety: what it is, how it affects using Dart, and how to migrate to it (properly!), and the Flutter releases that revealed and enhanced NNBD Dart (Flutter 2.0 and 2.2), at Flutter Engage and Google I/O 2021.

#flutter #dart null #dart

Mike  Kozey

Mike Kozey


Null Safety Support For Flutter & Dart

Dart serves an extraordinary part in Flutter, fueling developer highlights, for example, hot reload, and empowering multi-stage applications for mobile, desktop, and web utilizing Dart’s adaptable compiler innovation. We endeavor to make the Dart language the most useful for Flutter application developers; for instance, we added UI-as-code language builds to upgrade the Dart linguistic structure for coding Flutter widget trees.

In July 2020, sound null wellbeing was acquainted with the Dart programming language. As this language powers Flutter SDK, the help for null safety was one of the expected enhancements accompanying Flutter 2. We’re reporting a subsequent tech review of sound null safety, including support for the Flutter structure.

The arrival of the new Flutter on March 3, 2021, at last, made it conceivable not exclusively to compose new code utilizing the null safety include yet additionally to move the current Flutter applications to null safety. Null safety is a significant new efficiency highlight that assists you with staying away from null exemptions, a class of bugs that are regularly difficult to spot.

In this blog, we will explore the Null Safety Support for Flutter & Dart.We will take a look at how null safety is implemented in Flutter, how it influences the development process, what benefits it brings, and migrating to null safety in your flutter applications.

Table Of Contents ::

What is Sound null safety?

Why null safety?

What are Null safety design principles?

Unsound null safety

Making a null safety easier to use

Preferring to null safety

Migrating to null safety

Reasons to migrate a Flutter app to null safety


#dart #null-safety #flutter

Rocio  O'Keefe

Rocio O'Keefe


How Dart’s Null Safety Helped Me Augment My Projects

I migrated a running app and a published package to null safety, and it was awesome!

About the author:_ Waleed Arshad is a core mobile technologist, a passionate cross-platform developer, and the first person from Pakistan to become a Google Developer Expert for Flutter. After graduating from FAST Karachi, he has been working in the industry for more than five years and is currently working in the Developer Experience team for Flutter at Tendermint. He also leads Pakistan’s Flutter community._

With the launch of Flutter 2, null safety was made available to Flutter’s stable channel. This post talks about my personal experiences with migrating my apps and packages to null safety, along with creating null-safe apps from scratch. In short, the results were amazing!

If you aren’t aware of Flutter’s null safety feature, check out the announcement of null safety. If you want to fully understand null safety, check out the Dart documentation for null safety.

This article describes two of my experiences with null safety:

  • Migrating an app and a package
  • Writing new code in a null-safe environment

Migrating an app and a package

When I first upgraded Flutter to version 2.0 (the one that supports null safety) and updated my Dart SDK version to 2.12 in my Flutter app’s pubspec.yaml file, I saw a lot of errors. I wanted to initially try a manual migration to null safety (that is, migrate without the migration tool), so I started to resolve the null safety errors manually — adding question marks and exclamation points all over my code. I did all of that work intentionally, just to understand all the hard work done by the Flutter team on the null safety migration tool to automate the process of changing and updating the code! After some experimentation, I reverted all the manual changes I’d made by hand, and I used the magic of the tool to complete the migration of my app.

The application was an experimental COVID-19 stats app, and its code is fully open sourced. You can find it  on GitHub.

#dart #null-safety #flutter

Brain  Crist

Brain Crist


Dart sound null safety: technical preview 2

Dart serves a special role in Flutter, powering developer features such as hot reload, and enabling multi-platform apps for mobile, desktop, and web via Dart’s flexible compiler technology. We strive to make the Dart language the most productive for Flutter app developers; for example, we added UI-as-code language constructs to optimize the Dart syntax for coding Flutter widget trees.

In June we offered a first tech preview of null safety for Dart. Today is another major milestone, which we’ve looked forward to for a while: We’re announcing a second tech preview of sound null safety, including support for the Flutter framework.

Null safety is a major new productivity feature that helps you avoid null exceptions, a class of bugs that are often hard to spot. As an added bonus, this feature also enables a range of performance improvements. We’re really looking forward to your feedback.

Why null safety?

Dart is a type-safe language. This means that when you get a variable of some type, the compiler can guarantee that it is of that type. But type safety by itself doesn’t guarantee that the variable is not null.

Null errors are very common. A search on GitHub leads to thousands of issues caused by unexpected nulls in Dart code, and even more thousands of commits trying to fix those issues. Try to see if you can spot the nullability problems in the following Flutter app, imagining that Config and WeatherService are backend services used by the app:

This app will certainly fail if getAppName() returns a null; in that case we’ll pass a null to the Text widget used in the title of AppBar.

But there are more subtle cases to consider: getTemperatures() could also return null. In that case the for-loop will fail. Or getTemperatures() could return a list as expected, but that list might contain null values, in which case we’ll call round() on null, and the app will fail.

The null safety feature makes these problems go away by validating your code as you’re typing:

Screenshot of the preceding code with null errors.

With null safety, Dart finds potential null errors in your code.

With null safety, you can reason about your code with more confidence. No more pesky runtime null dereferencing errors in deployed apps. Instead, you get static errors as you code.

#programming #dart #null-safety #announcements #flutter

Waldo  Rippin

Waldo Rippin


Null Safety and Subclasses in Dart - The Devious Coin Trick

Randal demonstrates why the analyzer can’t guarantee that once a null check has been processed, the value is definitely not null for further steps.

#null safety #dart #devious coin trick