public/subjects/mobile-dev/circle/README.md

Circle

Instructions

Create a class named Circle.

Attributes:

• x: double
• y: double
• radius: double

Getters:

• area
• perimeter
• rightMostCoordinate: (x axis)
• leftMostCoordinate: (x axis)
• highestCoordinate: (y axis)
• lowestCoordinate: (y axis)

Constructor:

• x: required
• y: required
• radius: required

Getters and setters

Getters and setters avoid directly accessing or modifying attributes from outside of the class. They provide an opportunity to perform validation when setting attributes, or programmatically calculate values when getting attributes.

Consider a Vehicle that has batteryVoltage attribute. It is better that the lowBattery attribute is calculated based on the batteryVoltage, instead of being set directly.

In Dart, when you specify getters and setters, you must treat them as attributes.

Syntax of the getters and setters:

class Rectangle {
  double l, t, w, h;

  Rectangle(this.l, this.t, this.w, this.h);

  double get right => this.l + this.w;

  set left(double value) {
    if (value >= 0) {
      this.l = value;
    } else {
      throw new FormatException();
    }
  }

  double get bottom => this.t - this.h;

}

void main() {
  var rect = Rectangle(3, 4, 20, 15);
  rect.left = 12;
  print(rect.l);
}

Do not use math library, pi = 3.14