Bruce Eckel's Thinking in Java Contents | Prev | Next

Both inheritance and composition allow you to create a new type from existing types. Typically, however, you use composition to reuse existing types as part of the underlying implementation of the new type and inheritance when you want to reuse the interface. Since the derived class has the base-class interface, it can be upcast to the base, which is critical for polymorphism, as you’ll see in the next chapter.

Despite the strong emphasis on inheritance in object-oriented programming, when you start a design you should generally prefer composition during the first cut and use inheritance only when it is clearly necessary. (As you’ll see in the next chapter.) Composition tends to be more flexible. In addition, by using the added artifice of inheritance with your member type, you can change the exact type, and thus the behavior, of those member objects at run-time. Therefore, you can change the behavior of the composed object at run-time.


  • There are no comments yet. Be the first to comment!

Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • Lenovo recommends Windows 8 Pro. "I dropped my laptop getting out of the taxi." This probably sounds familiar to most IT professionals. If your employees are traveling, you know their devices are in for a rough go. Whether it's a trip to the conference room or a convention out of town, any time equipment leaves a user's desk it is at risk of being put into harm's way. Stay connected at all times, whether at the office or on the go, with agile, durable, and flexible devices like the Lenovo® …

  • U.S. companies are desperately trying to recruit and hire skilled software engineers and developers, but there's simply not enough quality talent to go around. In response, companies often resort to inferior solutions -- hiring substandard developers and engineers, recruiting talent on a part-time or temporary basis, poaching people from competitors, or burdening an already stressed IT staff for more of their labor. Fortunately, there's a better solution. Read this white paper to learn the business value of …

Most Popular Programming Stories

More for Developers

RSS Feeds

Thanks for your registration, follow us on our social networks to keep up-to-date