import java.awt.geom.AffineTransform;
...

// transform that shifts points 10 right and 20 up
AffineTransform transformer = AffineTransform.getTranslateInstance ( 10.0d, -20.0d );

// create point
Point2D before = new Point2D.Double( 3.0d , 6.0d );

// create point to hold result
Point2D after = new Point2D.Double();

// transform the point
after = transformer.transform ( before, after );

// prints 13.0,-14.0
out.println( after.getX() + "," + after.getY() );