Java™ How To Program (Early Objects), Tenth Edition

Interface Lock and Class ReentrantLock

Any object can contain a reference to an object that implements the Lock interface (of package java.util.concurrent.locks). A thread calls the Lock’s lock method (analogous to entering a synchronized block) to acquire the lock. Once a Lock has been obtained by one thread, the Lock object will not allow another thread to obtain the Lock until the first thread releases the Lock (by calling the Lock’s unlock method—analogous to exiting a synchronized block). If several threads are trying to call method lock on the same Lock object at the same time, only one of these threads can obtain the lock—all the others are placed in the waiting state for that lock. When a thread calls method unlock, the lock on the ...