Explanation/Reference:
A: setRollbackOnly
Mark the current transaction for rollback. The transaction will become permanently marked for rollback. A transaction marked for rollback can never commit. Only enterprise beans with container-managed transactions are allowed to use this method.
Note:
* In a stateless session bean with bean-managed transactions, a business method must commit or roll back a transaction before returning.
* Bean-Managed Transactions
In bean-managed transaction demarcation, the code in the session or message-driven bean explicitly marks the boundaries of the transaction. Although beans with container-managed transactions require less coding, they have one limitation: When a method is executing, it can be associated with either a single transaction or no transaction at all. If this limitation will make coding your bean difficult, you should consider using bean-managed transactions.
* (incorrect) Unchecked runtime exceptions represent conditions that, generally speaking, reflect errors in your program's logic and cannot be reasonably recovered from at run time.
Incorrect:
B: getRollbackOnly
Test if the transaction has been marked for rollback only. An enterprise bean instance can use this operation, for example, to test after an exception has been caught, whether it is fruitless to continue computation on behalf of the current transaction. Only enterprise beans with container-managed transactions are allowed to use this method.