Flutter how it works, Hello World
Tags: flutter
Published: 2021-07-03 05:25:54

When learning a new language, Dart, in this case, it's a good starting point to go back to the basics.
So today, I'll explore the minimum requirements for a basic Hello World app in Flutter.

## How Flutter works

Before we get started with this, let's have a look at how Flutter actually works.
I won't go into all the nitty-gritty details, but more a high-level view.

Flutter is Google's version of a hybrid framework, much like [Ionic](https://daily-dev-tips.com/tags/ionic/) or React native.

One single codebase for all your projects, including mobile and web. Sounds pretty cool, right!

The big catch is that it's using Dart, a new language for many.

Flutter uses its own rendering methods compared to the other frameworks.
It also should be performing better in terms of speed.

## A sample Hello World in Flutter

I got pretty confused at first when looking at the basic counter-example Flutter app, it showed me some widgets and extended codebases, and I had no clue what was going on.

So I decided to go back to the most basic app that I could create. It needed only to render some text.

So start up a new flutter app, and clear the complete code in the `lib/main.dart` file.

We will start by importing the flutter package. This allows us to use some ready-made widgets.

```dart
import 'package:flutter/material.dart';
```

In the Dart language, we must always define a `main` function. This is the case for Dart files, so also for flutter applications.

In a basic Dart example, we could do something like this:

```dart
void main() {
  print('Hello World 👋');
}
```

Running this code will show us a blank Flutter app, but log `Hello World 👋` in the console.

In Flutter, we need to include a `runApp` function inside this main function.
This function will run your flutter app.

We want to have some content inside this `runApp` function that shows our Hello World.

For this, we can leverage the `Center` widget that comes with Flutter. Inside this widget, we can pass a child, in our case, a Text widget containing our text.

```dart
void main() {
  runApp(
    Center(
      child: Text(
        'Hello World 👋',
        textDirection: TextDirection.ltr,
      ),
    ),
  );
}
```

And when we now run our app with `flutter run`, we should see our very first Flutter application.

![Hello World in Flutter](https://cdn.hashnode.com/res/hashnode/image/upload/v1624808501935/ryVCDKGbg.png)

However, we can leverage Flutter scaffolding to make this a bit cleaner.

```dart
void main() async {
  runApp(
    MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: MyApp(),
      ),
    ),
  );
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: Text(
        'Hello World 👋',
        textDirection: TextDirection.ltr,
      ),
    );
  }
}
```

This code will render the same app, but as you see, Flutter is very widget-driven, much like what you'll see in React.

The idea is that we build our app out of widgets. These widgets describe what their view should look like, given a specific state and configuration. When the state of these widgets changes, it is rebuilt with the new configuration.

I like this concept, as it also forces us to think out an app design-wise and extend widgets throughout our application.

For today we learned the very basics of Dart and Flutter and created a hello world application.

I've also uploaded this to my [GitHub](https://github.com/rebelchris/flutter/tree/hello-world) branch.

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