naming methods and variables : Java Glossary

by Roedy Green ©1996-2008 Canadian Mind Products
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naming methods and variables

You might find some of the suggestions for terrible names in the "How To Write Unmaintainable Code" section of the Java & Internet Glossary instructive.

Technical Requirements	Interfaces
Meaningful Method Names	Plurals
Hungarian Notation	Links

Technical Requirements

Names of identifiers for classes, methods and names can in theory be arbitrarily long. They are limited only by the 32-bit 2 gigabyte addressing limit of Strings. In practice though, non-local names often end up inside class file which has its own limits which tend to based around 16-bit addressibility. The only restriction is they must start with a Java letter, upper or lower case. That list of Java letters includes _ and $, though $ should only be used for mechanically generated code since JavaC uses $ in constructing names for anonymous classes. If you are unsure what constitutes a Java letter use, Character. isJavaIdentifierStart( int ). The category casts a broad net, and includes all kinds of foreign alphabets. The rest of the identifier can also contain the digits 0-9.

Meaningful Method Names

One of the most time-consuming and often neglected coding tasks, is renaming methods and variables to give ever clearer intentions. The idea is to suggest in the name exactly what the method does, no more, no less. You also want to distinguish it easily from all similar (non-overloaded) methods. You have to balance the pain you cause forcing client code to rename against the potential for confusion during future maintenance. A tool like IBM’s VAJ takes out most of the pain. Most of this renaming work goes on in the early stages of code development before the first release of a class. You would be amazed how much renaming a method or variable helps you understand your own code. It greatly aids the composition process. It gives you better tools to think with.

If you can’t come up with a good name for a method, there is a good chance your method is not sufficiently unified, and you should repartition the work.

Hungarian Notation

If you use any variant of Hungarian notation where you put type information in your name, make sure you maintain it. If you change the type of the variable or method, you must globally rename it. Experiences with inaccurate Hungarian notation cause most maintenance programmers to detest detest all forms of Hungarian notation.

Local Variables

The conventions for single letter local variables date back to FORTRAN days. IntelliJ inspector enforces them.

int	i, j, k, m, n
float	f
double	d
byte	b
char	c, ch
long	l
String	s, str

Interfaces

Interfaces are usually adjectives, e.g. Serializable, Externalizable. Classes that are related to each other should have names that are related e.g. BaseShape, CircularShape and RectangularShape.

Plurals

Arrays and Sets should have plural names. e.g.

coding conventions
JLS
unmaintainable code

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