Program to calculate area of rectangle

class RectArea{
float length,breadth;
double area;
void setValue(float l,float b){
length=l;
breadth=b;
}
void calculate(){
area=(double)length*breadth;
System.out.println("Area of Rectangle : "+area);
}
}
class Rect{
public static void main(String args[]) {
RectArea r=new RectArea();
r.setValue(12,20);
r.calculate();
}
}