How to Catch Exception

[dinesh thalis]

I'm using EJB3. As usual, i'll use the EntityManager's API to do CRUD operation, such as, em.persist(), em.merge() etc.

So now I want to catch exception while performing em.persist() and do my own thing.

If I used @TransactionManagement(TransactionManagementType.BEAN) I can handle exception below show my code.

 
@TransactionManagement(TransactionManagementType.BEAN)
    public void create(Account account) {
        try {
            em.persist(account);
        } catch (Exception e) {
            System.out.println(e);
        }
    }
   

Problem is if I use @TransactionManagement(TransactionManagementType.CONTAINER) I can't catch exception, I used same code( display above), how can I overcome this problem.

If you can provide more details about exception handling in EJB3( reference link) it's more helpful to me.

[Rodrigo Lazoti]

You can handle/catch exceptions in BMT or CMT Enterprise Beans.
See the links below more about transactions and handling of exceptions:

http://java.sun.com/javaee/5/docs/tutorial/doc/bncih.html
http://java.sun.com/javaee/5/docs/tutorial/doc/bnbpj.html

And I recommend you check the specs:

http://jcp.org/aboutJava/communityprocess/final/jsr244/index.html


Best Regards!

[Rodrigo Lazoti]

duplicate message. sorry...

[Yair Ivan]

Hi.


Thanks Rodrigo for information.

I add the following items:

- In EJB 3 in Action section 6.2.5 Transaction and exception handling.
- In Entreprise JavaBeans 3.0 (O´Relly) Section 16.6 Exceptions and Transactions.

By.

[dinesh thalis]

I read this tutorials but still I'm fail

public void create(Account account) {  
         try {  
             em.persist(account);  
         } catch (Exception e) {  
            System.out.println("I want to print my custom exception ");  
         }  
}  

I'm using container manager transaction and persist account details. if some body try to persist incorrect account information I want to give customer exception(message) instead of system generated message. Above code show that but this not work. please help me how to it?

[Jaikiran Pai]

With CMT, the actual queries are fired on transaction completion, i.e. after the method exits. So the catch block will never be able to catch such exceptions which happen within a transaction synchronization callback. You'll see the difference if you add a em.flush after the em.persist. That way, the queries will be fired immediately instead of waiting for tx synchronization:

try {    
              em.persist(account);    
               em.flush(); // fire now
          } catch (Exception e) {    
             System.out.println("I want to print my custom exception ");    
          }    

[dinesh thalis]

Below show how I try to handle this issue. Is it write or wrong. Using this way I can succeed some extend, Is there any suggestion regarding this.

public void create(Account account) {
        try {
            em.persist(account);
            em.flush();
            em.clear();
        } catch (Exception e) {
            context.setRollbackOnly();
            System.out.println("I want to print my custom exception "); 
        }
    }