volatile variable & synchronized

[Edward Chen]

if I have a volatile variable, do I still need to synchronized it ?

In Doc, it said, volatile will force thread NOT to cache object, only one copy in main memory, but it doesn't say concurrent access is safe.

for example,

volatile String str;

synchronized(str){
   //.... 
}

Thanks.

[Henry Wong]

Edward Chen wrote:if I have a volatile variable, do I still need to synchronized it ?

In Doc, it said, volatile will force thread NOT to cache object, only one copy in main memory, but it doesn't say concurrent access is safe.

It depends on the operation. A single get or set of the reference is atomic. Anything more than that, is not, and will require you to use the atomic classes (or synchronization).

Henry

[Campbell Ritchie]

Moving topic as not a "beginning" topic.