Java multithreaded Programming--Static synchronization functions

// a hungry man, safe in multi-threaded  Public class Single {    privatestaticfinal single s=new single ();     Private Single () {};      Public Static Single getinstance () {        return  s;    }}

//lazy, non-thread safe, must use synchronous Public classSingle {Private StaticSingle s=NULL; PrivateSingle () {};  Public StaticSingle getinstance () {if(s==NULL)            synchronized(Single.class){//static synchronization, where the lock is the bytecode file object of the class in which the method resides                if(s==NULL) s=NewSingle (); }        returns; }}

Java multithreaded Programming--Static synchronization functions