What is semaphore in Java?

In Java, semaphore manages access to a shared resource by the use of a counter and if the counter is bigger than zero, then access is granted else if it is zero, then access is refused. What the limiter is counting are permits that allow access to the shared resource. Thus, to obtain the resource, a thread must be granted a permit from the semaphore. Technically, to use a semaphore, the thread that needs access to the shared resource attempts to acquire a permit.