design pattern

• Don’t use patterns unless you need to.

• Don’t use patterns that you don’t fully understand.

• Don’t expect that whoever is going to work on the code in the future to recognize and understand the patterns that you used – stick to common patterns, and make them explicit in comments where you think it is important or necessary.

• When you’re changing code, take some time to look for and understand the patterns that might be in place, and decide whether it is worth preserving (or restoring) them: whether doing this will really make the code better and more understandable.

ref:http://java.dzone.com/articles/design-patterns-after-design