multithreading - Java synchronization with callback -

i developing module inside system based on event user has receive sms.

i have following situation

synchronized(notificationphonenumber) {     smsprovider.sendsms(notificationphonenumber, smstext); } 

the code of method sendsms running asynchronious:

public static void send(final notificationphonenumber npn, final string smstext) {     thread smssender = new thread(new runnable()     {         public void run()         {            //sms sending code runs here....         }      });       smssender.start(); } 

so question how long notificationphonenumber object locked in case? going locked time thread finishes job or not?

as long

 smsprovider.sendsms(notificationphonenumber, smstext); 

doesn't return. means, sendsms() method create thread , return. amount of time.

also, if start thread in method. created thread hold reference not lock after sendsms() returns.

the lock , synchronization external sendsms(). whichever thread calls sendsms() acquire lock , code within sendsms() has no knowledge of it.