java.util.concurrent.locks

The java.util.concurrent.locks package provides a more flexible and powerful mechanism for handling synchronization in Java compared to the traditional synchronized methods and blocks. It offers various types of locks and synchronization utilities that can help manage concurrent access to shared resources in multi-threaded applications.

Key Classes and Interfaces

1. Lock Interface
   • The Lock interface defines methods for acquiring and releasing locks. It provides greater flexibility compared to the synchronized blocks or methods. Implementations of this interface offer different types of locking strategies.
2. ReentrantLock Class
   • ReentrantLock is the most commonly used implementation of the Lock interface. It allows a thread to acquire a lock multiple times without causing a deadlock. It also provides additional features like timed lock waits and interruptible lock waits.
3. ReadWriteLock Interface
   • This interface defines a pair of locks, one for read operations and one for write operations. It allows multiple threads to read concurrently as long as no thread is writing, which can improve performance in read-heavy scenarios.
4. ReentrantReadWriteLock Class
   • ReentrantReadWriteLock is a commonly used implementation of the ReadWriteLock interface. It provides separate locks for reading and writing, and it is reentrant, meaning that the same thread can acquire the read or write lock multiple times.
5. Condition Interface
   • The Condition interface allows threads to wait and be notified of changes to the state of an object. It is an alternative to using the Object class’s wait(), notify(), and notifyAll() methods.
6. StampedLock Class
   • StampedLock provides a more advanced locking mechanism with support for optimistic locking. It offers methods for locking and unlocking with stamps, and can be used for scenarios where performance is critical, and the contention is low.

This example demonstrates how to use ReentrantLock and Condition to handle synchronization in a more flexible and efficient way compared to traditional synchronized methods.