Re: What does this exception mean

[Robert Sfeir]

You seem to be looking for a missing object obviously, my guess is that  
your PersistenceBroker instance object is somehow null the first time  
around, and when you run it again, you seem to have a condition which  
creates the object properly.

Be sure that:
1- You're not calling broker.close() if you're going to reuse the  
PersistenceBroker instance again
2- You're always getting a new instance before running a new query
3- That you don't have your connection pool connections set too low,  
because that might be yet another problem where you might be trying to  
get a connection, but there are none left in the pool.  That can be  
cause by various reasons including:
	a- Too little connections available (increase it in the repository xml  
database definition)
	b- You're NOT calling broker.close() when you're done with your query,  
hence leaving connections open for a long while.
	c- There are simply no more connections available on the DB end to be  
opened, but that's more unlikely.

HTH
R
On Apr 17, 2004, at 11:06 AM, Peter Wieland wrote:

Hi folks,

from time to time I get the following exception querying my db. I have  
no
idea what this means. Executing the same query a few seconds later  
(just by
clicking the button that triggers the query one more time) passes  
without
any problems.

Caused by: org.apache.ojb.broker.PersistenceBrokerException:
java.lang.NullPointerException
	at  
org.apache.ojb.broker.core.QueryReferenceBroker.getCollectionByQuery(Qu 
e
ryReferenceBroker.java:250)
	at  
org.apache.ojb.broker.core.QueryReferenceBroker.getCollectionByQuery(Qu 
e
ryReferenceBroker.java:262)
	at  
org.apache.ojb.broker.core.PersistenceBrokerImpl.getCollectionByQuery(P 
e
rsistenceBrokerImpl.java:1093)
	at  
org.apache.ojb.broker.core.DelegatingPersistenceBroker.getCollectionByQ 
u
ery(DelegatingPersistenceBroker.java:322)
	at  
org.apache.ojb.broker.core.DelegatingPersistenceBroker.getCollectionByQ 
u
ery(DelegatingPersistenceBroker.java:322)
	at  
de.armax.base.entity.persistence.AXpersistenceBrokerOjb.getVector(AXper 
s
istenceBrokerOjb.java:222)
	... 61 more
Caused by: java.lang.NullPointerException
	at  
org.apache.ojb.broker.core.PersistenceBrokerImpl.getTopLevelClass(Persi 
s
tenceBrokerImpl.java:1639)
	at  
org.apache.ojb.broker.core.QueryReferenceBroker.getReferencedObjectIden 
t
ity(QueryReferenceBroker.java:433)
	at  
org.apache.ojb.broker.core.QueryReferenceBroker.retrieveReference(Query 
R
eferenceBroker.java:339)
	at  
org.apache.ojb.broker.core.QueryReferenceBroker.retrieveReferences(Quer 
y
ReferenceBroker.java:400)
	at  
org.apache.ojb.broker.accesslayer.RsIterator.getObjectFromResultSet(RsI 
t
erator.java:498)
	at  
org.apache.ojb.broker.accesslayer.RsIterator.next(RsIterator.java:293)
	at  
org.apache.ojb.broker.core.QueryReferenceBroker.getCollectionByQuery(Qu 
e
ryReferenceBroker.java:146)
	at  
org.apache.ojb.broker.core.QueryReferenceBroker.getCollectionByQuery(Qu 
e
ryReferenceBroker.java:242)
	... 66 more

Any ideas?

Peter

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