What are the scenarios where Java transaction annotations fail to work effectively?

In Java, there are several scenarios where transaction annotations become ineffective.

1. Annotations should be placed on non-public methods: transaction annotations can only take effect on methods that are marked as public. If placed on non-public methods, transaction annotations will be ineffective.
2. Self-invocation method: If a method calls itself within the same class (instead of being called through a proxy object), the transaction annotation will be ineffective. This is because Spring’s transactions are implemented through proxy objects, and self-invocation methods bypass the proxy object, causing the transaction annotation to be ineffective.
3. If an exception is caught within a method without being rethrown, the transaction annotation will become ineffective. This is because Spring’s transaction rollback mechanism is based on exceptions, and the exception within the method must be rethrown in order to trigger the transaction rollback.
4. Annotations should be placed on private methods: transaction annotations only work on methods that are public. If a transaction annotation is placed on a private method, it will be ineffective.
5. Annotations should be placed on beans that are managed by Spring. Transaction annotations will only take effect on beans managed by Spring. Placing them on beans not managed by Spring will render the transaction annotations ineffective.

It is important to note that the scenarios above only apply to annotation-based transaction management. If you are using programmatic transaction management, these scenarios may not apply. Additionally, different versions and configurations of Spring may have some differences, so the specific failure scenarios could vary.