Abstractizare java

Abstractizare.java

abstract class Shape {

     abstract double calculateArea(); //metoda abstracta, FARA implementare

     void display() {

         System.out.println("Aria formei este: " + calculateArea());
     }
}

//subclasa 1: implementare concreta
class Circle extends Shape {

      double radius;

      Circle(double radius) {
         this.radius = radius;
      }

      @Override
      double calculateArea() {
         return Math.PI * radius * radius;
      }

}

//subclasa 2: implementare concreata clasa Patrat
class Square extends Shape {

double side;

Square(double side) {
   this.side = side;
}

@Override
double calculateArea() {
   return side * side;
}


}

public class Abstractizare {

         public static void main(String[] args) {

                Shape circle =  new Circle( 4 );

                Shape square =  new Square( 5 );

                circle.display();

                square.display();
         }
}


//Animal: Caine, Pisica, Pelican

//MAsina: BMW, Audo, Dacia, Porsche

interface Shape {

     double calculateArea(); //public
     double calculatePerimeter();
}


class Circle implements Shape {

    double radius;

    Circle(double radius) {
       this.radius = radius;
    }

    @Override
    public double calculateArea() {
            return Math.PI * radius * radius;
    }

    @Override
    public double calculatePerimeter() {
            return 2 * Math.PI * radius;
    }
}


class Square implements Shape {

    double side;

    Square(double width, double height) {
       this.width = width;
       this.height = height;
    }

    @Override
    public double calculateArea() {
            return side * side
    }

    @Override
    public double calculatePerimeter() {
            return 2 * (width + height);
    }
}

//O interfata este un CONTRACT care spune ce metode trebuie sa aiba o clasa, fara sa spuna cum sunt implementate.
//O forma pura de abstractizare