A Rectange object specifics a rectangular area in the coordinate system.
Its x and y fields specify the top-left corner coordinate.
Its width and height fields specify the width and height of the rectangle, respectively.
Here are some of the constructors of the Rectangle class.
public Rectangle ()
public Rectangle (Dimension d)
public Rectangle (int width, int height)
public Rectangle (int x, int y, int width, int height)
A zero value for a field is assumed if the field is missing from a constructor's argument list.