IOstreams and the Decorator Pattern (The solution)

• We gain two things:

• • The “old” interface is preserved – Every Reader decorator can “pass” as a Reader object (i.e. is transparent).
  • We can “chain” several functionalities – We can now decorate a specific Reader with several types of decorations. Example: adding both line reading capabilities and efficient reading capability (see example below).

• The Same solution exists for Writer, InputStream and OutputStream classes.

• In Java, “decorators” are called “Filters”, and the base class for adding attributes is FilterXXX.