Question

will deadlock occur in these Java situations
1-

synchronized(obj) {
   obj.syncMethod(); // the method signature: public synchronized void syncMethod() {...}
}

2-

synchronized(obj) {
  if (condition) 
     throw new Exception(); // deadlock because obj lock is not released?
  // do other stuff
}

Thank you.

Answer 1

1. No deadlock will occur – Java’s locks are reentrant, that is, while a thread is holding a lock (in your case on obj) it can enter synchronized blocks requiring the same lock without problem (a synchronized method is synchronized on this, which is obj in your case too).
2. The lock will be released when the synchronized block is left, no matter whether an exception causes the thread to leave it or not.