About final constants in Java library classes

system (_)
本文发表在 rolia.net/zh 相约加拿大网上社区枫下论坛
Q: I see that some Java library classes define some final constants. By curiosity, I printed out some of these final constants using "System.out.println(...)". I observed that most of these constants are just simple numbers such 0, 1, 2. Why other to define them?

A: If you use 0, 1 , 2 ... directly in the code, you may forget what they mean in a few days. In addition, the same number can stand for different things in a different contexts.

Hence, people usuall call these numbers "magic numbers". Remember this world, it will help to talk Java as a native Canadian does.

Ia a real project, it is a common practice to define an interface to hold all the final constants.

For instance, if you buikd a Web site using Java servlet and JSP, you can define an interface called PageNames to collect all the page names. By doing so, you can avoid hard-code pages in your source files so that they can be easily maintained. In a job interview, I have been asked: Where is the good place to define constants for a project?
更多精彩文章及讨论,请光临枫下论坛. 网址: rolia.net/zh
(#8039@0)
2000-9-4 -05:00

回到话题: Java Q&A (2) (compiled by jabber)

回到论坛: HOME枫下论坛枫下论坛主坛工作学习IT技术讨论

URL:   
http://www.rolia.net/zh/post.php?f=0&p=8039