The Semaphore class present in java.util.concurrent package is a COUNTING semaphore in which a semaphore, conceptually, MAINTAINS a set of permits. Thread that wants to access the shared resource tries to acquire a PERMIT using acquire() METHOD. At that time if the Semaphore's count is greater than zero thread will acquire a permit and Semaphore's count will be decremented by one. If Semaphore's count is zero, when thread calls acquire() method, then the thread will be blocked until a permit is available. When thread is done with the shared resource access, it can call the release() method to release the permit. That results in the Semaphore's count incremented by one.

The Semaphore class present in java.util.concurrent package is a counting semaphore in which a semaphore, conceptually, maintains a set of permits. Thread that wants to access the shared resource tries to acquire a permit using acquire() method. At that time if the Semaphore's count is greater than zero thread will acquire a permit and Semaphore's count will be decremented by one. If Semaphore's count is zero, when thread calls acquire() method, then the thread will be blocked until a permit is available. When thread is done with the shared resource access, it can call the release() method to release the permit. That results in the Semaphore's count incremented by one.