Reading a shared primitive variable in one thread may not yield the value of the most recent write to the variable from another thread. Consequently, the thread may observe a stale value of a the shared variable. Visibility of the most recent update can be ensured by declaring the variable as volatile or correctly synchronizing the reads and writes to the variable.
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Synchronization is a more secure alternative in situations where the volatile keyword or a java.util.concurrent.atomic.Atomic* field is inappropriate, such as if a variable's new value depends on its old value. Refer to CON01-J. Ensure that compound operations on shared variables are atomic for more information on compound operations.
Exceptions
CON00-EX1: Objects of type Class need not be made visible because they are created by the Virtual Machine and their initialization always precedes any subsequent use JMM Mailing List.
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