How does sealed classes behave in multithreaded code?

Sealed classes in Java provide a way to control which classes can subclass or implement them. When working with multi-threaded code, sealed classes behave the same way as regular classes regarding thread safety and synchronization. However, since sealed classes limit subtype inheritance, they can sometimes provide more predictable behavior in a concurrent environment by constraining the number of interacting types.

It's important to manage shared state and synchronization properly, regardless of whether a class is sealed or not. Developers should implement mechanisms like synchronized blocks, locks, or other concurrency controls to ensure that shared resources are accessed safely in a multi-threaded context. This is particularly important when dealing with mutable state.