This month's installment of Design Techniques is the second in a mini-series of columns about designing objects. In last month's column, which covered designing objects for proper initialization, I talked about how to design constructors and initializers. This month and next month I'll discuss design principles for the actual fields and methods of the class. After that, I'll write about finalizers and show how to design objects for proper cleanup at the end of their lives.
The material for this article (avoiding special data values, using constants, minimizing coupling) and the next article (maximizing cohesion) may be familiar to many readers, as the material is based on general design principles that are quite independent of the Java programming language. Nevertheless, because I have encountered so much code over the years that doesn't take advantage of these principles, I think they deserve to be restated from time to time. In addition, in this article I attempt to show how these general principles apply to the Java language in particular.
