import Box;

class BoxExample
{
    public static void main (String[] args)
    {
       Box myFirstBox = new Box();
       myFirstBox.setWidth (7.5);
       double w = myFirstBox.getWidth();
       
       System.out.println ("Antes de llamar al método: w = " + w + " width = " + myFirstBox.getWidth());
       BoxExample ex = new BoxExample ();
       ex.doubleWidth (w, myFirstBox);
       System.out.println ("Después de llamar al método: w = " + w + " width = " + myFirstBox.getWidth());

    }
    void doubleWidth (double w, Box b)
    {
       w = w * 2;
       b.setWidth (w);
       System.out.println ("Dentro del método: w = " + w + " width = " + b.getWidth());
     }
}