Java Concurrency Control Methods

In Java, you can use the following methods for concurrency control:

1. The synchronized keyword: Using the synchronized keyword can lock a code block or method to ensure that only one thread can enter the critical section at a time, thus avoiding data race and inconsistency issues caused by concurrent access.
2. The ReentrantLock class in Java is an explicit lock that allows locking and unlocking operations using the lock() and unlock() methods. Unlike synchronized, ReentrantLock provides a more flexible locking mechanism, such as reentrancy and fairness.
3. Semaphore class: Semaphore is a type of counting semaphore used to control concurrent access. It limits the number of threads accessing a resource simultaneously, and permits are acquired and released using the acquire() and release() methods.
4. CountDownLatch is a synchronization aid that allows one or more threads to wait for other threads to complete operations before proceeding.
5. The CyclicBarrier class is a synchronization utility used for multiple threads to wait for each other. It allows a group of threads to wait for each other at a certain barrier point before continuing execution simultaneously.
6. Phaser class: Phaser is a synchronization aid class for controlling the synchronization of multiple threads in stages. It supports multi-phase synchronization and offers a more flexible control mechanism.

These methods allow for selecting an appropriate way to control concurrency based on actual needs, ensuring the correctness and efficiency of multi-threaded programs.