Java volatile modifier and synchronized blocks

Question

Does a variable that is accessed by multiple threads, but only inside synchronized blocks, need the volatile modifier? If not, why?

Answer 1

You do not need to use volatile inside of synchronized, synchronized already guarantees the correct behavior for local caching of variables when used consistently (on every access).

volatile works on primitive values, and can be a nice shortcut for atomic accesses to a primitive type. Note that the behavior of volatile has changed in JDK 5 from 1.4.

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