Learning Dart through Google's Code Labs

bicycle.dart

class Bicycle { 
  int cadence;
  int _speed; // private & read-only variable using underscore
  int gear;
   
  Bicycle(this.cadence, this._speed, this.gear); 
   
  int get speed => _speed; 
   
  void applyBrake(int decrement) {
    _speed -= decrement;
  } 
   
  void speedUp(int increment) {
    _speed += increment;
  } 
   
  @override 
  String toString() => 'Bicycle: $_speed mph, gear: $gear';
} 
 
void main() { 
  var bike = new Bicycle(2, 0, 1);
  print(bike);
  
} 

functional.dart

String scream(int length) {
  return "A${'a' * length}h!";
}

main() {
  var values = [1, 2, 3, 5, 10, 50];
  //values.map(scream).forEach(print);
  
  values.skip(1).take(3).map(scream).forEach(print); // 2, 3, 5
  
  /*for (var length in values) {
    print(scream(length));
  }*/
}

rectangle.dart

import 'dart:math';

class Rectangle {
  int width;
  int height;
  Point origin;
  
  Rectangle({this.origin = const Point(0,0), this.width = 0, this.height = 0}); // named & default parameters
  
  @override
  String toString() => 'Origin: (${origin.x}, ${origin.y}), Width: $width, Height: $height';
}

main() {
  print(new Rectangle(origin: const Point(10, 20), height: 200, width: 100)); // position can be changed
  print(new Rectangle(origin: const Point(10, 10)));
  print(new Rectangle(width: 100));
  print(new Rectangle());
  
}

shapes.dart

import 'dart:math';

abstract class Shape {
  num get area;
  
  factory Shape(String type) {
    if (type == 'circle') return new Circle(2);
  	if (type == 'square') return new Square(3);
  	throw 'Can\'t create $type.';
  }
}

class Circle implements Shape {
  final num radius;
  Circle(this.radius);
  num get area => PI * pow(radius, 2);
}

class Square implements Shape {
  final num side;
  Square(this.side);
  num get area => pow(side, 2);
}

class CircleMock implements Circle {
  num area;
  num radius;
}

/*
 * Shape shapeFactory(String type) {
  		if (type == 'circle') return new Circle(2);
  		if (type == 'square') return new Square(3);
  		throw 'Can\'t create $type.';
	 }
*/

main() {
  var circle = new Shape('circle');
  var square = new Shape('square');
  print(circle.area);
  print(square.area);
  try {
    var rhombus = new Shape('rhombus'); // Uncaught exception
  }
  catch (err) {
    print(err);
  }  
  
}