synchronized(this){}

[zserzs]

All,

I ran into the following question in a Java test:

- Why the compiler is not removing this code?

synchronized(this){}

Does the question ask that it is not removed despite of the fact that we'd like to synchronize an empty statement?
What is the correct answer?

Thanks!

Zs.

[KevinWorkman]

The question is asking, why can't the compiler remove that, since it appears to do nothing? Presumably, the compiler can remove empty statements and code that won't be reached. Why can't the compiler remove that statement?

[zserzs]

The question is asking, why can't the compiler remove that, since it appears to do nothing? Presumably, the compiler can remove empty statements and code that won't be reached. Why can't the compiler remove that statement?

Okay, makes perfect sense... But why?

[KevinWorkman]

Okay, makes perfect sense... But why?

That's the assignment. Why do you think? What does the synchronized keyword do?

[zserzs]

That's the assignment. Why do you think? What does the synchronized keyword do?

Okay, let's do it this way :)
Here are my thoughts:
the synchronized keyword makes it sure that there could be only one read/write operation at a time... so it might be the case that synchronized(this) synchronizes the current working object for I'm-not-sure-what-context and does it even if that block is empty...

Is it super-stupid, or not that bad?

Thanks,
Zs.

[zserzs]

Kevin,
I had lunch, I've been thinking on this...
Here are my thoughts:

Given a point in time where we are at the line synchronized(this){}. Now, all previous locks has to be released, so this line basically does nothing, but separates code before and after it. I've never seen this in practice, though.... Am I closer?

Zs.

[Whired]

all previous locks has to be released

Seems like a good answer to me? A moniterenter would mean waiting until the lock object is unmonitored. I can't think of why someone would need to, but removing this would seem to change how the program works.