Is the creation of Java class files deterministic?

Question

When using the same JDK (i.e. the same javac executable), are the generated class files always identical? Can there be a difference depending on the

Answer 1

There are two questions.

Can there be a difference depending on the operating system or hardware? 

This is a theoretical question, and the answer is clearly, yes, there can be. As others have said, the specification does not require the compiler to produce byte-for-byte identical class files.

Even if every compiler currently in existence produced the same byte code in all circumstances (different hardware, etc.), the answer tomorrow might be different. If you never plan to update javac or your operating system, you could test that version's behavior in your particular circumstances, but the results might be different if you go from, for example, Java 7 Update 11 to Java 7 Update 15.

What are the circumstances where the same javac executable, when run on a different platform, will produce different bytecode?

That's unknowable.

I don't know if configuration management is your reason for asking the question, but it's an understandable reason to care. Comparing byte codes is a legitimate IT control, but only to determine if the class files changed, not top determine if the source files did.