Thread-safe list Java

Thread-safe list Java

I'll respond in English for this question.

Thread-Safe List in Java

In multithreaded programming, it's crucial to ensure that data structures used by multiple threads are thread-safe. A thread-safe list in Java means that the list can be accessed and modified by multiple threads concurrently without causing any issues or errors.

To achieve thread safety in a list, you need to use synchronization techniques. One common approach is to use the ArrayList class provided by Java, which is not inherently thread-safe. Instead, you can use a CopyOnWriteArrayList, which is designed for multithreaded environments. This class makes a copy of the entire list every time an element is added or removed.

Here's why CopyOnWriteArrayList is thread-safe:

However, keep in mind that CopyOnWriteArrayList can be slower than using a synchronized ArrayList, as it requires more memory and CPU resources to create those snapshots.

Another option is to use the Collections.synchronizedList() method, which wraps an existing list with a synchronization mechanism. This allows you to use any thread-safe collection class (such as a Vector) and ensures that only one thread can access the list at a time.

Here's how to do it:

List myList = Collections.synchronizedList(new ArrayList());

When using this approach, make sure to synchronize access to the list using methods like list.add() or list.remove(), as shown below:

synchronized (myList) {
myList.add("new element");
}

In conclusion, there are multiple ways to create a thread-safe list in Java. The choice between using CopyOnWriteArrayList or Collections.synchronizedList() depends on your specific requirements and constraints.

References:

Which Java Collections are thread-safe and not thread-safe?

In the Java world, understanding which collections are thread-safe and which aren't is crucial when building concurrent applications.

Thread-Safe Collections:

Non-Thread-Safe Collections:

Important Note:

Even though some collections are thread-safe, it's crucial to understand that simply using one of these collections does not automatically make your application thread-safe. You still need to properly synchronize access to the collection using Java's built-in concurrency utilities or other synchronization mechanisms (e.g., locks, semaphores, monitors).

When working with concurrent collections, it's also essential to consider the specific use case and requirements of your application. For instance, if you only have a single thread accessing a particular collection, there may be no need for thread-safety guarantees.

To sum up: