Java – why doesn’t the acquire () method in semaphores have to be synchronized?

I'm using java to enter semaphores and reading this article http://docs.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/Semaphore.html. The only thing I don't get is why the acquire () method is not used in the context of synchronization Take an example of the website above:

They created a semaphore:

private Semaphore semaphore = new Semaphore(100);

And obtain such a license:

semaphore.acquire();

Now, is it possible for two or more threads to try to get () at the same time? If so, there will be a problem with counting

Or, does the semaphore itself process synchronization?

Solution

Yes, basically Semaphores are thread safe, as described in the Javadoc:

java. util. Most operations on objects in the concurrent package are thread safe More details are provided at the bottom of the package Javadoc