Does the singleton bean in Spring ensure safe usage in a multithreaded environment?

A singleton bean in Spring is created once per container and used everywhere dependencies are injected. However, this does not guarantee thread safety.

Thread safety depends on the class implementation:

• If the bean contains mutable state without synchronization, it will not be thread-safe.
• If the bean is stateless (without state) or uses thread-safe structures and mechanisms, it can be safely used in multithreaded environments.

Thus, Spring does not automatically ensure thread safety for singleton beans — it is the developer's responsibility to ensure thread safety in the class.