interface

package shapecunt;

public class ShapeCunt {

    public static void main(String[] args) {

    }

}
---------------------------------

package shapecunt;

public interface Calculatable {
    public static final double PI = 3.14;
    public static double calcArea() {
        return 0.0;
    };
}
-----------------------------------

package shapecunt;

// area = 3.14*r2
public class Circle implements Calculatable {
    private double r;

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

    public double getR() {
        return r;
    }

    public void setR(double r) {
        this.r = r;
    }

    public double calcArea() {
        return Calculatable.PI * getR();
    }

}
------------------------------------

package shapecunt;

public class Triangle implements Calculatable {
    private double height ;
   private double base ;

    /**
     * @return the height
     */
    public double getHeight() {
        return height;
    }

    /**
     * @param height the height to set
     */
    public void setHeight(double height) {
        this.height = height;
    }

    /**
     * @return the base
     */
    public double getBase() {
        return base;
    }

    /**
     * @param base the base to set
     */
    public void setBase(double base) {
        this.base = base;
    }
    public double calcArea () {
   return getBase() * getHeight() * 0.5;
    }
}