Lock interface supports locking disciplines that differ in semantics (reentrant, fair, etc), and that can be used in non-block-structured contexts including hand-over-hand and lock reordering algorithms. The main implementation is
ReadWriteLock interface similarly defines locks that may be shared among readers but are exclusive to writers. Only a single implementation,
ReentrantReadWriteLock, is provided, since it covers most standard usage contexts. But programmers may create their own implementations to cover nonstandard requirements.
Condition interface describes condition variables that may be associated with Locks. These are similar in usage to the implicit monitors accessed using
Object.wait, but offer extended capabilities. In particular, multiple
Condition objects may be associated with a single
Lock. To avoid compatibility issues, the names of
Condition methods are different from the corresponding
AbstractQueuedSynchronizer class serves as a useful superclass for defining locks and other synchronizers that rely on queuing blocked threads. The
AbstractQueuedLongSynchronizer class provides the same functionality but extends support to 64 bits of synchronization state. Both extend class
AbstractOwnableSynchronizer, a simple class that helps record the thread currently holding exclusive synchronization. The
LockSupport class provides lower-level blocking and unblocking support that is useful for those developers implementing their own customized lock classes.
Interface Summary Interface Description Condition Lock
Lockimplementations provide more extensive locking operations than can be obtained using
synchronizedmethods and statements.
ReadWriteLockmaintains a pair of associated
locks, one for read-only operations and one for writing.
Class Summary Class Description AbstractOwnableSynchronizerA synchronizer that may be exclusively owned by a thread. AbstractQueuedLongSynchronizerA version of
AbstractQueuedSynchronizerin which synchronization state is maintained as a
AbstractQueuedSynchronizerProvides a framework for implementing blocking locks and related synchronizers (semaphores, events, etc) that rely on first-in-first-out (FIFO) wait queues. LockSupportBasic thread blocking primitives for creating locks and other synchronization classes. ReentrantLockA reentrant mutual exclusion
Lockwith the same basic behavior and semantics as the implicit monitor lock accessed using
synchronizedmethods and statements, but with extended capabilities.
ReentrantReadWriteLock ReentrantReadWriteLock.ReadLockThe lock returned by method
ReentrantReadWriteLock.WriteLockThe lock returned by method
StampedLockA capability-based lock with three modes for controlling read/write access.