| <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN"> |
| <html> <head> |
| <title>Locks</title> |
| </head> |
| |
| <body> |
| |
| Interfaces and classes providing a framework for locking and waiting |
| for conditions that is distinct from built-in synchronization and |
| monitors. The framework permits much greater flexibility in the use of |
| locks and conditions, at the expense of more awkward syntax. |
| |
| <p> The {@link java.util.concurrent.locks.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 {@link java.util.concurrent.locks.ReentrantLock}. |
| |
| <p> The {@link java.util.concurrent.locks.ReadWriteLock} interface |
| similarly defines locks that may be shared among readers but are |
| exclusive to writers. Only a single implementation, {@link |
| java.util.concurrent.locks.ReentrantReadWriteLock}, is provided, since |
| it covers most standard usage contexts. But programmers may create |
| their own implementations to cover nonstandard requirements. |
| |
| <p> The {@link java.util.concurrent.locks.Condition} interface |
| describes condition variables that may be associated with Locks. |
| These are similar in usage to the implicit monitors accessed using |
| <tt>Object.wait</tt>, but offer extended capabilities. In particular, |
| multiple <tt>Condition</tt> objects may be associated with a single |
| <tt>Lock</tt>. To avoid compatibility issues, the names of |
| <tt>Condition</tt> methods are different than the corresponding |
| <tt>Object</tt> versions. |
| |
| <p> The {@link java.util.concurrent.locks.AbstractQueuedSynchronizer} |
| class serves as a useful superclass for defining locks and other |
| synchronizers that rely on queuing blocked threads. The {@link |
| java.util.concurrent.locks.LockSupport} class provides lower-level |
| blocking and unblocking support that is useful for those developers |
| implementing their own customized lock classes. |
| |
| @since Android 1.0 |
| |
| </body> </html> |
