What are some examples of synchronization in Java?

What are some examples of synchronization in Java?

In Java, synchronization is used to control access to shared resources. Here are a few examples:

1. Synchronized Methods: You can declare a method as synchronized to ensure that only one thread can execute it at a time.
2. Synchronized Blocks: Instead of synchronizing the entire method, you can synchronize a block of code within a method to improve performance.
3. Reentrant Locks: Java provides the ReentrantLock class which offers more flexibility than synchronized methods and blocks.
4. CountDownLatch: This is a synchronization aid that allows one or more threads to wait until a set of operations being performed in other threads completes.
5. Semaphore: This is used to control access to a resource by multiple threads.

Can you explain synchronized methods in more detail?

Sure! A synchronized method in Java is a method that is declared with the synchronized keyword. When a thread calls a synchronized method, it acquires the lock for that method's object. This means that if another thread tries to call any synchronized method on the same object, it will be blocked until the first thread releases the lock. This helps prevent thread interference and ensures that the method's execution is thread-safe.

What about synchronized blocks? How do they differ from synchronized methods?

Synchronized blocks are more granular than synchronized methods. Instead of locking the entire method, you can lock only a specific block of code. This is done using the synchronized keyword followed by an object reference. This allows for better performance because it reduces the scope of the lock, enabling other threads to access non-synchronized parts of the method while one thread is executing the synchronized block.

Can you give an example of a synchronized block?

Certainly! Here's a simple example:

public void updateResource() {
    synchronized(this) {
        // critical section code that modifies shared resource
    }
}

In this example, only the code inside the synchronized block will be locked, allowing other threads to execute code outside of this block concurrently.