Like others have said, a static method cannot call a non-static method, whether it's synchronized or not. That's simple.
But it is possible for a non-static synchronized method to call a static synchronized method. However, the
thread that's calling the static method may need to wait for the static method's lock to be released.
Static synchronized methods use the class's Class object as a lock. So the follow two methods are equivalent:
Non-static synchronized methods use the current object instance as a lock. So these two methods are equivalent: