Final answer:
Singleton beans are not inherently thread-safe; they can be thread-safe if stateless or immutable or accessed with proper synchronization.
Step-by-step explanation:
Singleton beans in a Spring context are designed such that only one instance of the bean is created for the entire application. Whether singleton beans are thread-safe depends on how they are implemented within the application. Singleton beans themselves are not inherently thread-safe; that is, the bean instance is shared, but access to the bean's properties and methods needs to be properly handled in the presence of multiple threads. If a singleton bean has shared mutable state, special care must be taken to ensure that it is accessed in a thread-safe manner, typically through synchronization or by avoiding mutable state altogether. On the other hand, if a singleton bean is stateless or its state is immutable, then it is naturally thread-safe as there is no mutable state to manage across threads.