Design Patterns Java™ Workbook

Refactoring to Strategy

The getRecommended() method presents several problems. First, it's long—long enough that comments have to explain its various parts. Short methods are easy to understand, seldom need explanation, and are usually preferable to long methods. In addition, the getRecommended() method chooses a strategy and then executes it; these are two different and separable functions. You can clean up this code by applying STRATEGY. To do so, you need to

• Create an interface that defines the strategic operation

• Implement the interface with classes that represent each strategy

• Refactor the code to select and to use an instance of the right strategic class

Suppose that you create an Advisor interface and begin your refactoring by introducing ...