[Java] [Bridge Pattern]

Consider a shape display system which can display shapes in several output formats.

All shape classes in the system have a deferred class SHAPE as their ancestor. For example, the following figure shows part of the shape hierarchy:

Classes SCREEN and PRINTER are used to display shapes on a screen or printer respectively:

class SCREEN

feature

draw_line (x1, y1, x2, y2: INTEGER) is ?? Display a line from (x1, y1) to (x2, y2).

draw_pixel (x, y: INTEGER) is ?? Display a pixel at (x, y).

draw_circle (x, y, r: INTEGER) is ?? Display a circle at (x,y) with radius r.

end

class PRINTER feature

print_line (x1, y1, x2, y2: INTEGER) is ?? Print a line from (x1, y1) to (x2, y2).

print_pixel (x, y: INTEGER) is ?? Print a pixel at (x, y).

print_circle (x, y, r: INTEGER) is ?? Print a circle at (x,y) with radius r.

end

Design a system which allows new shapes and new output formats to be added easily (Bridge Pattern?). You are required to add a new shape POLYGON and a new output format XML_WRITER.

SHAPE CIRCLE RECTANGLE SHAPE CIRCLE RECTANGLE