program to demonstrate Generics (example of generic class)

// Using Generics
class Data<T> {
  T data;
  Data(this.data);
}

void main() {
  // create an object of type int and double
  Data<int> intData = Data<int>(10);
  Data<double> doubleData = Data<double>(10.5);

  // print the data
  print("IntData: ${intData.data}");
  print("DoubleData: ${doubleData.data}");
}

________________________________________________________________________________________________________

// Define generic method
T genericMethod<T>(T value) {
  return value;
}

void main() {
  // call the generic method
  print("Int: ${genericMethod<int>(10)}");
  print("Double: ${genericMethod<double>(10.5)}");
  print("String: ${genericMethod<String>("Hello")}");
}

________________________________________________________________________________________________________

program to define and calling generic method with parameters

// Define generic method
T genericMethod<T, U>(T value1, U value2) {
  return value1;
}

void main() {
  // call the generic method
  print(genericMethod<int, String>(10, "Hello"));
  print(genericMethod<String, int>("Hello", 10));
}

________________________________________________________________________________________________________

// Define generic class with bounded type
class Data<T extends num> {
  T data;
  Data(this.data);
}

void main() {
  // create an object of type int and double
  Data<int> intData = Data<int>(10);
  Data<double> doubleData = Data<double>(10.5);
  // print the data
  print("IntData: ${intData.data}");
  print("DoubleData: ${doubleData.data}");
  // Not Possible
  // Data<String> stringData = Data<String>("Hello");
}

________________________________________________________________________________________________________

example of generic class

// abstract class Shape
abstract class Shape {
  // abstract method area
  double get area;
}

// class Circle which implements Shape
class Circle implements Shape {
  // field radius
  final double radius;
  // constructor
  Circle(this.radius);

  // implementation of area method
  @override
  double get area => 3.14 * radius * radius;
}
// class Rectangle which implements Shape
class Rectangle implements Shape {
  // fields width and height
  final double width;
  final double height;
  // constructor
  Rectangle(this.width, this.height);

  // implementation of area method
  @override
  double get area => width * height;
}

// Generic class Region
class Region<T extends Shape> {
  // field shapes
  List<T> shapes;
  // constructor
  Region({required this.shapes});

  // method totalArea
  double get totalArea {
    double total = 0;
    shapes.forEach((shape) {
      total += shape.area;
    });
    return total;
  }
}

void main() {
  // create objects of Circle and Rectangle
  var circle = Circle(10);
  var rectangle = Rectangle(10, 20);
  // create a list of Shape objects
  var region = Region(shapes: [circle, rectangle]);
  // print the total area
  print("Total Area of Region: ${region.totalArea}");
}

________________________________________________________________________________________________________