Device coordinates are integers.
A point represents a PIXEL.
Study the APIs for the following java.awt classes:
Point
Rectangle
See project 3
Real coordinates are floats or doubles.
A point represents a point in a real plane.
Java automatically maps real coordinates into device coordinates.
See the APIs for the following java.awt.geom classes:
Point2D.Double
Rectangle2D.Double
Ellipse2D.Double