Non-uppercase constants in Java

Question

This question about why constants in Java are uppercase by convention made me try to think of counter examples.

I can think of at least one (Double.NaN). Are there others?

Answer 1

Of course, public final static PrintStream out (in java.lang.System.out). But it's a very good exception, because System.OUT.println is just ugly.

Also, most of the time loggers are initialized as follows:

private static final Logger logger = Logger.getLogger(MyClass.class);

However, in both cases these are not constants in the true sense of the term. So perhaps we can make a distinction:

Fields that are static because they need a static access, and final because they should not be re-assigned at runtime, are not necessarily constants.

Answer 2

There are lots of serialVersionUID!

Others in ResultSetMetaData like columnNoNulls, columnNullable...
DatabaseMetaData and ICC_Profile have lots of mixed case constants.

Here is a list with most, if not all, JavaSE constants: Constant Field Values

Answer 3

Color constants like black, red, green etc from java.awt.Color class.

It should be noted that java.awt.Color also provides the uppercase alternatives (e.g. BLACK, RED, GREEN etc) of these constants.