Dart Tutorials from Google

Bicycle.dart

class Bicycle 
{
  Bicycle(this.cadence, this.gear);
  
  int cadence;
  int gear;
  int _speed = 0;
  int get speed => _speed;
  // fat arrow notation "=>" are only used when the return type or the statement can
  // be fit into one line, thus eliminating "return"
  void applyBrake(int decrement) => _speed -= decrement;
  void speedUp(int increment) { _speed += increment; }
  @override String toString() => "Bicycle speed: $speed mph";
}

void main(List<String> args)
{
  var x = Bicycle(3, 4);
  print(x.toString());
}

Rectangle.dart

import 'dart:math';

class Rectangle {
  int width;
  int height;
  Point origin;
  Rectangle({this.width = 0, this.height = 0, this.origin = const Point(0,0)});
  @override String toString() => "Origin: (${origin.x}, ${origin.y}), width: $width, height: $height";
}

main() {
  // specify the attribute u want to provide and the ones not provided by the programmer
  // will be provided by the optional default parameter. very clever way to make overloading
  // much more concise. this feature is like always having a "master" constructor in java
  // where this constructor has all of the necessary parameters (max parameters needed)
  print(Rectangle(origin: const Point(10, 20), width: 100, height: 200));
  print(Rectangle(origin: const Point(10, 10)));
  print(Rectangle(width: 200));
  print(Rectangle());

}