Flutter syntax and keywords examples

Certainly! Here are some key syntax elements and concepts in Dart and Flutter, along with examples to help you get started:

Dart Syntax and Concepts

1. Variables and Types

   • Dart is statically typed but also supports type inference with the var keyword.

     int number = 42;
     var name = 'Alice'; // Type inference as String

2. Functions

   • Functions in Dart are first-class objects and have a return type, parameters, and a body.

     String greet(String name) {
     return 'Hello, $name!';
     }

3. Control Flow Statements

   • Similar to C# and PHP, Dart has if, else, for, while, and do-while.

     for (var i = 0; i < 5; i++) {
     print('index $i');
     }

4. Classes and Object-Oriented Programming

   • Dart is an object-oriented language. Classes, objects, inheritance, etc., are all available.

     class Animal {
     void speak() {
     print('The animal makes a sound');
     }
     }

     class Dog extends Animal {
     @override
     void speak() {
     print('Bark!');
     }
     }

5. Asynchronous Programming

   • Dart uses Future and Stream along with async and await for handling asynchronous operations, similar to tasks in C#.

     Future fetchData() async {
     // Imagine that this function is fetching data from the internet
     await Future.delayed(Duration(seconds: 2));
     print('Data fetched');
     }

Flutter Specifics

1. Widgets

   • Everything in Flutter is a widget, from a simple text to a complex layout.

     Text('Hello, Flutter!', style: TextStyle(fontSize: 24));

2. Layouts

   • Use widgets like Row, Column, and Container to layout your UI.

     Column(
     children: [
     Text('Hello, Flutter!'),
     ElevatedButton(onPressed: () {}, child: Text('Press Me'))
     ],
     )

3. State Management

   • Flutter has StatelessWidget and StatefulWidget for managing the UI state.

     
     class MyWidget extends StatefulWidget {
     @override
     _MyWidgetState createState() => _MyWidgetState();
     }

   class _MyWidgetState extends State {
   int _counter = 0;

   void _incrementCounter() {
   setState(() {
   _counter++;
   });
   }

   @override
   Widget build(BuildContext context) {
   return Scaffold(
   appBar: AppBar(title: Text('Counter App')),
   body: Center(child: Text('You pressed the button $_counter times')),
   floatingActionButton: FloatingActionButton(
   onPressed: _incrementCounter,
   tooltip: 'Increment',
   child: Icon(Icons.add),
   ),
   );
   }
   }

4. Material and Cupertino Design

   • Flutter provides a rich set of pre-designed widgets following Material Design (for Android) and Cupertino (for iOS).

     MaterialApp(
     title: 'Flutter Demo',
     theme: ThemeData(
     primarySwatch: Colors.blue,
     ),
     home: MyWidget(),
     );

5. Navigation

   • Navigate between screens using routes.

     Navigator.push(
     context,
     MaterialPageRoute(builder: (context) => SecondScreen()),
     );

These examples should give you a basic idea of Dart and Flutter's syntax and concepts. As you progress, you'll discover more advanced features and best practices.