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

Coming up with a design such as that contains a larger amount of code than the earlier designs can seem at first to be counterproductive. It pays to notice what you’re trying to accomplish with various designs. Design patterns in general strive to separate the things that change from the things that stay the same . The “things that change” can refer to many different kinds of changes. Perhaps the change occurs because the program is placed into a new environment or because something in the current environment changes (this could be: “The user wants to add a new shape to the diagram currently on the screen”). Or, as in this case, the change could be the evolution of the code body. While previous versions of the trash-sorting example emphasized the addition of new types of Trash to the system, allows you to easily add new functionality without disturbing the Trash hierarchy. There’s more code in, but adding new functionality to Visitor is cheap. If this is something that happens a lot, then it’s worth the extra effort and code to make it happen more easily.


  • 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  • Your email address will not be published.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

  • Moving from an on-premises environment to Office 365 does not remove the need to plan for disruptions or reduce the business risk requirements for protecting email services. If anything, some risks increase with a move to the cloud. Read how to ease the transition every business faces if considering or already migrating to cloud email. This white paper discusses: Setting expectations when migrating to Office 365 Understanding the implications of relying solely on Exchange Online security Necessary archiving …

  • Enterprises are increasingly looking to platform as a service (PaaS) to lower their costs and speed their time to market for new applications. Developing, deploying, and managing applications in the cloud eliminates the time and expense of managing a physical infrastructure to support them. PaaS offerings must deliver additional long-term benefits, such as a lower total cost of ownership (TCO), rapid scalability, and ease of integration, all while providing robust security and availability. This report …

Most Popular Programming Stories

More for Developers

RSS Feeds

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