Shape interface + implementations

Circle.java

public class Circle implements Shape {

    private int radius;

    public Circle(int r) {
        this.radius = r;
    }

    @Override
    public void perimeter() {
        System.out.println("Area = " + (2 * Math.PI * radius));
    }

    @Override
    public void area() {
        System.out.println("Area = " + (Math.PI * Math.pow(radius, 2)));
    }
}

Main.java

public class Main {

    public static void main(String[] args) {
        Shape square = new Square(2);
        square.area();

        Shape rec = new Rectangle(2, 4);
        rec.area();

        Circle cir = new Circle(5);
        cir.area();
    }
}

Rectangle.java

public class Rectangle implements Shape {

    private int base, height;

    public Rectangle(int h, int b) {
        this.base = b;
        this.height = h;
    }

    @Override
    public void perimeter() {
        double calculatePer = Math.pow(base, 2) + Math.pow(height, 2);
        System.out.println("Perimeter = " + calculatePer);
    }

    @Override
    public void area() {
        double calculateArea = base * height;
        System.out.println("Area = " + calculateArea);
    }
}

Shape.java

public interface Shape {

    public void perimeter();
    public void area();

}

Square.java

public class Square implements Shape {

    private int length;

    public Square(int len) {
        this.length = len;
    }

    @Override
    public void perimeter() {
        System.out.println("perimeter");
    }

    @Override
    public void area() {
        double calculatedArea = Math.pow(length, 2);
        System.out.println("Area = " + calculatedArea);
    }
}