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Java-to-Dart codelab: Factory constructor
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import 'dart:math'; | |
abstract class Shape { | |
factory Shape(String type) { | |
if (type == 'circle') return new Circle(2); | |
if (type == 'square') return new Square(2); | |
throw 'Can\'t create $type.'; | |
} | |
num get area; | |
} | |
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); | |
} | |
main() { | |
var circle = new Circle(2); | |
var square = new Square(2); | |
print(circle.area); | |
print(square.area); | |
} |
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