Design Patterns Java™ Workbook

Collaboration within a Class

The constructors of a well-designed class usually interact. Consider what happens when we need to add a classification attribute to the Firework class so that each firework is classified as a consumer firework or as a display-type firework. Figure 14.2 shows the Firework class picking up firework classification constants from the ClassificationConstants interface and adding a Classification attribute.

Figure 14.2. The Firework class “inherits” classification constants by implementing the ClassificationConstants interface.

CHALLENGE 14.3 Suppose that you want to use constructors to establish the default classification ...