Design a class to find area of parameter of circle and also used the class in main method

Design a class to find area of parameter of circle and also used the class in main method in java 

class Test{

    int r;

    void set(int radius){

        r=radius;

    }

    double area(){

        double a= 3.14*r*r;

        return a;

    }

    double parameter(){

        return (2*3.14*r);

    }

}

class Main{

    public static void main(String args[]){

        Test obj=new Test();

        int r=5;

        obj.set(r);

        double a=obj.area();

        double p=obj.parameter();

        System.out.println("Circle area "+a);

        System.out.println("Circle of Parameter "+p);

    }

}