dart 类 class

void main() {
  var myClass = firstClass();
  var a = myClass.Point(1,2);
  print(a);
  print(myClass.z);
}
class firstClass {
  num x;
  num y;
  num z = 200;
  Point(num x, num y) {
    // There's a better way to do this, stay tuned.
    this.x = x;
    this.y = y;
    var x2 = 2*this.x;
    var y2 = 2*this.y;
    print(x2);
    return [x2, y2];
  }
}
//output
2
[2, 4]
200