Design Patterns Java™ Workbook

Flyweight (Chapter 13)

SOLUTION 13.1

The BorderFactory class in javax.swing is a good example of FLYWEIGHT. As its class comment says, “Wherever possible, this factory will hand out references to shared Border instances.” When a Border object can be safely shared, BorderFactory will return the same border more than once. For example, every call to createEmptyBorder() will return the same, empty border.

SOLUTION 13.2

An argument for the immutability of strings: In practice, strings are frequently shared between clients and thus frequently the crux of defects that emerge when one client inadvertently affects another. For example, a method that returns a customer's name as a string will typically retain its reference to the name. If the client, say, ...