What Makes a Method Thread-safe? What are the rules?

Question

Are there overall rules/guidelines for what makes a method thread-safe? I understand that there are probably a million one-off situations, but what about in general? Is it t

Answer 1

It must be synchronized, using an object lock, stateless, or immutable.

link: http://docs.oracle.com/javase/tutorial/essential/concurrency/immutable.html