The Lock interface (and the ReentrantLock class) includes another method to get control of the lock. It's the tryLock() method. The biggest difference with the lock() method is that this method, if the thread that uses it can't get control of the Lock interface, returns immediately and doesn't put the thread to sleep. It returns the boolean value true if the thread gets control of the lock and false if not. You can also pass a time value and a TimeUnit object to indicate the maximum amount of time the thread will wait to get the lock. If the time elapses and the thread doesn't get the lock, the method will return the false value. The TimeUnit class is an enumeration with the following constants: DAYS, HOURS, MICROSECONDS, MILLISECONDS, MINUTES, NANOSECONDS, and SECONDS; these indicate the units of time we pass to a method.

The ReentrantLock class also allows the use of recursive calls. When a thread has control of a lock and makes a recursive call, it continues with the control of the lock, so the calling to the lock() method will return immediately and the thread will continue with the execution of the recursive call. Moreover, we can also call other methods. You should call the unlock() method as many times as you called the lock() method in your code.