// object lock doubt

[Meg Adal]

In Exam Cram book they have stated like this:

A single thread can obtain locks on many objects and/or multiple locks on same object

I think last part of statement is incorrect.
I guess as there is only one lock with given object ,thread can't obtain multiple locks on same object
correct me if I am wrong

Thanks in advance
Megan

[Jose Botella]

Imagine that the methods are protected by different locks as it follows:
method1() { synchronized(lock1) {method2();} }
method2() { synchronized(lock2) {} }
A thread calling method1 will obtain two locks (if available)

[Anthony Villanueva]

Also, see this link.

[Ron Newman]

But those are two locks on two different objects (lock1 and lock2).
I think the statement really means that the same thread can lock the same object more than once, so this code won't deadlock:

synchronized void method1() {
   {method2();} 
synchornized void method2() {}

[Paul Villangca]

Hi all,
I think it's more like re-acquiring the lock of an object than obtaining multiple locks of the same object. This is to prevent instances like a thread waiting for a lock that it already has.