The Robert C. Martin Clean Code Collection (Collection) (Robert C. Martin Series)

by Robert C. Martin

Consider Listing 6-3 and Listing 6-4. The first uses concrete terms to communicate the fuel level of a vehicle, whereas the second does so with the abstraction of percentage. In the concrete case you can be pretty sure that these are just accessors of variables. In the abstract case you have no clue at all about the form of the data. Listing 6-3 Concrete Vehicle public interface Vehicle { double getFuelTankCapacityInGallons(); double getGallonsOfGasoline(); } Listing 6-4 Abstract Vehicle public interface Vehicle { double getPercentFuelRemaining(); } In both of the above cases the second option is preferable. We do not want to expose the details of our data. Rather we want to express our data in abstract terms. This is not merely accomplished by using interfaces and/or getters and setters. Serious thought needs to be put into the best way to represent the data that an object contains. The worst option is to blithely add getters and setters.