Enterprise JavaBeans, Fourth Edition

Exception Handling

Exception handling is particularly relevant to this discussion because, unlike in container-managed persistence, in bean-managed persistence the bean developer is responsible for throwing the correct exceptions at the right moments. For this reason, we’ll take a moment to discuss the different types of exceptions in BMP. This discussion will be useful when we get into the details of database access and implementing the callback methods.

Bean-managed beans throw three types of exceptions:

Application exceptions

Application exceptions include standard EJB application exceptions and custom application exceptions. The standard EJB application exceptions are CreateException, FinderException, ObjectNotFoundException, DuplicateKeyException, and RemoveException. These exceptions are thrown from the appropriate methods to indicate that a business logic error has occurred. Custom exceptions are exceptions developed for specific business problems. We cover developing custom exceptions in Chapter 11.

Runtime exceptions

Runtime exceptions are thrown from the virtual machine itself and indicate that a fairly serious programming error has occurred. Examples include the NullPointerException and IndexOutOfBoundsException. These exceptions are handled by the container automatically and should not be handled inside a bean method.

You will notice that all the callback methods (ejbLoad( ), ejbStore( ), ejbActivate( ), ejbPassivate( ), and ejbRemove( )) throw an EJBException when a ...