Things to avoid

Magic numbers, especially if they appear in more than one place. They really want to be named constants, but they also have to be named in a way that is not dependent on the actual value. For example, worldPopulation = 6,973,738,433.

The five (5) principles

... and here they are:

• Single responsibility!
• Open-closed! (but watch out for: single responsibility)
• Liskov substitution!
• Interface segregation! (see also: single responsibility)
• Dependency inversion!

No ParkHelper for you

FAIL:

../../../gcc-4.6.2/libjava/include/jvm.h:795:3: error: `ParkHelper' does not name a type