How do you define a macro in Java?

Java itself doesn’t support macros. On the other hand, you could pipe the source code through the C preprocessor (CPP for short) just like the C/C++ compile chain does.

Java doesn’t have a general purpose define preprocessor directive . private static final int PROTEINS = 100; Such declarations would be inlined by the compilers (if the value is a compile-time constant).18 Ara 2009

A preprocessor is a program that works on the source before the compilation . As the name implies, the preprocessor prepares the source for compilation. The notion of the preprocessor has been there from the earliest times of programming languages.