java - getting NullPointerException when using syncrhonized on null object -

i have seen nullpointerexception on synchronized statement.

code:

synchronized(a){     = new a() } 

so according above answer i have understood not possible use synchronized keyword on null reference.

so changed code this:

synchronized(a = new a()){} 

but not sure if identical original code?

update:

what want achieve lock creation of a ( a = new a() )

synchronized(a = new a()){}

so create new object of class , use lock, in simple word every thread can enter in synchronized block anytime because each thread have new lock , there no other thread using object lock every thread can enter synchronized block anytime , outcome no synchronization

for example

class testclass {     someclass somevariable;      public void mymethod () {         synchronized (somevariable) {             ...         }     }      public void myothermethod() {         synchronized (somevariable) {             ...         }     } } 

here can 2 blocks protected execution of 2 different threads @ time while somevariable not modified. basically, it's said 2 blocks synchronized against variable somevariable. but in case there new object there no synchronization