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A quote from the Java Threads book about the volatile keyword

I'm just wondering if anyone can explain the meaning of this:

Operations such as increment and decrement (for example, ++and --) cannot be used for a volatile variable, because these operations are syntactic sugar for loading, modifying and storing.

I think increment and decrement should work just fine for a volatile variable, the only difference would be each time you read or write, you will access from / write to main memory, not from cache.

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No - you use "volatile" to indicate that a variable can be modified by an external object. Usually it will be some JNI C code, or a special register associated with some equipment, for example, with a thermometer. Java cannot guarantee that all JVMs on all architectures may be able to increment these values ​​in a single machine cycle. Therefore, it does not allow you to do this anywhere.

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