6.8.5 Constant Names

The names of constants in interface types should be, and final variables of class types may conventionally be, a sequence of one or more words, acronyms, or abbreviations, all uppercase, with components separated by underscore "_" characters. Constant names should be descriptive and not unnecessarily abbreviated. Conventionally they may be any appropriate part of speech. Examples of names for constants include MIN_VALUE, MAX_VALUE, MIN_RADIX, and MAX_RADIX of the class java.lang.Character.

A group of constants that represent alternative values of a set, or, less frequently, masking bits in an integer value, are sometimes usefully specified with a common acronym as a name prefix, as in:

interface ProcessStates {
	int PS_RUNNING = 0;
	int PS_SUSPENDED = 1;
}

Hiding involving constant names is rare:

• Constant names should be longer than three letters, so that they do not hide the initial component of a unique package name.
• Constant names normally have no lowercase letters, so they will not normally hide names of packages, types, or fields, whose names normally contain at least one lowercase letter.
• Constant names cannot hide method names, because they are distinguished syntactically.