Re: Strange null pointer exceptions

Jan Berkel Tue, 07 Oct 2003 07:15:55 -0700

I keep getting NullPointerExceptions while retrieving an object from the database (OJB 1.0RC4).

my repository_user.xml is set up as explained in the tutorials (extent-class in Template/BaseTemplate etc., to be sure I also used ojbConcreteClass to specify the classname)
Please post the repository_user.xml.  I guess an attribute or
field-descriptor is missing there.

NB: I use the xdoclet module to generate the mappings:

<class-descriptor
   class="cabane.templates.Template"
   table="TEMPLATES"
>
   <extent-class class-ref="cabane.templates.BaseTemplate"/>
   <extent-class class-ref="cabane.templates.MailTemplate"/>
</class-descriptor>

<class-descriptor
   class="cabane.templates.BaseTemplate"
   proxy="dynamic"
>
   <extent-class class-ref="cabane.templates.MailTemplate"/>
</class-descriptor>

<class-descriptor
   class="cabane.templates.MailTemplate"
   table="TEMPLATES"
>
   <field-descriptor
       name="id"
       column="ID"
       jdbc-type="INTEGER"
       primarykey="true"
       autoincrement="true"
   >
   </field-descriptor>
   <field-descriptor
       name="name"
       column="NAME"
       jdbc-type="VARCHAR"
   >
   </field-descriptor>
   <field-descriptor
       name="language"
       column="LANGUAGE"
       jdbc-type="VARCHAR"
   >
   </field-descriptor>
   <field-descriptor
       name="content"
       column="CONTENT"
       jdbc-type="VARCHAR"
   >
   </field-descriptor>
</class-descriptor>

Another valuable hint could be a stacktrace with line numbers.

test: [junit] Testsuite: cabane.templates.TemplateTest [junit] Tests run: 1, Failures: 1, Errors: 0, Time elapsed: 3,119 sec [junit] ------------- Standard Error ----------------- [junit] java.lang.NullPointerException [junit] at org.apache.ojb.broker.metadata.ClassDescriptor.getPkFields(Cl assDescriptor.java:893) [junit] at org.apache.ojb.broker.accesslayer.RsIterator.getIdentityFromR esultSet(RsIterator.java:378) [junit] at org.apache.ojb.broker.accesslayer.RsIterator.getObjectFromRes ultSet(RsIterator.java:424) [junit] at org.apache.ojb.broker.accesslayer.RsIterator.next(RsIterator. java:254) [junit] at org.apache.ojb.broker.accesslayer.ChainingIterator.next(Chain ingIterator.java:357) [junit] at org.apache.ojb.broker.core.PersistenceBrokerImpl.getCollectio nByQuery(PersistenceBrokerImpl.java:1374) [junit] at org.apache.ojb.broker.core.PersistenceBrokerImpl.getCollectio nByQuery(PersistenceBrokerImpl.java:1515) [junit] at org.apache.ojb.broker.core.PersistenceBrokerImpl.getCollectio nByQuery(PersistenceBrokerImpl.java:1551) [junit] at org.apache.ojb.broker.core.PersistenceBrokerImpl.getCollectio nByQuery(PersistenceBrokerImpl.java:1540) [junit] at org.apache.ojb.broker.core.PersistenceBrokerImpl.getObjectByQ uery(PersistenceBrokerImpl.java:1802) [junit] at org.apache.ojb.broker.core.DelegatingPersistenceBroker.getObj ectByQuery(DelegatingPersistenceBroker.java:286) [junit] at org.apache.ojb.broker.core.DelegatingPersistenceBroker.getObj ectByQuery(DelegatingPersistenceBroker.java:286) [junit] at cabane.persistence.OJBPersistence.getTemplate(OJBPersistence. java:246)

reagarding the "skipped" message I think you're right, it only occurred when I put the field descriptors in the base _and_ extended class.

regards,
   Jan

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Re: Strange null pointer exceptions

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