Static synchronization vs instance var synchrnisation

[navi shrav]

hi all,
can anybody help me understand as to how a static variable is synchronized verses an instance variable or the difference in the two.
thanks in advance.

[Anthony Villanueva]

Hi Navi, variables can't be directly synchronized. Only methods and code blocks can be synchronized. Please see the Sun tutorial on synchronization.

[Ron Newman]

It is, however, possible for static methods to be synchronized -- the lock lives in the Class object.

[Ilya PA]

Hi Navi,
Actually as far as i know you can synchronize a variable. U can do that placing the 'volatile' keyword before a variable's name. This is often used with variables of size bigger then a CPU word size. For example normal PIII word size is 32bits, but variables of type long and double are 64bit vars. So when one thread loads a part of a long var to the cpu(first 32bits), another thread should not be able to access that variable.

[Leslie Chaim]

Yes but as noted in a rather heated debate over the Behaviour of Volatile variables you will see how Peter Haggar lays out the facts

[Jim Baiter]

If you're talking about synchronizing static methods there is a difference. In this case the class lock is acquired whereas with the non-static method the object lock is acquired.