Hey there.

I read that ClassCastException for StringType are likely mapping discrepencies, so I've triple-checked my mapping types against my POJOs. I even removed the types alltogether. Yet, I'm still lost with this ClassCastException.

What am I missing? Thanks.

Hibernate version:
3.0.5 & 3.1rc1

Mapping documents and POJOs:
http://www.firestruck.com/temp/Patient.hbm.xml
http://www.firestruck.com/temp/Address.hbm.xml
http://www.firestruck.com/temp/Patient.java
http://www.firestruck.com/temp/Address.java

Full stack trace of any exception that occurs:
[java] 2843 [main] DEBUG org.hibernate.SQL - select patient0_.id as id0_, patient0_.dob as dob1_0_, patient0_.first_name as first3_1_0_, patient0_.gender as gender1_0_, patient0_.last_name as last5_1_0_, patient0_.middle_name as middle6_1_0_, patient0_.phone as phone1_0_, patient0_.ssn as ssn1_0_, patient0_.address_id as address9_1_0_ from patient patient0_ where patient0_.id=?
[java] Hibernate: select patient0_.id as id0_, patient0_.dob as dob1_0_, patient0_.first_name as first3_1_0_, patient0_.gender as gender1_0_, patient0_.last_name as last5_1_0_, patient0_.middle_name as middle6_1_0_, patient0_.phone as phone1_0_, patient0_.ssn as ssn1_0_, patient0_.address_id as address9_1_0_ from patient patient0_ where patient0_.id=?
[java] 2843 [main] DEBUG org.hibernate.jdbc.AbstractBatcher - preparing statement
[java] 2843 [main] DEBUG org.hibernate.type.IntegerType - binding '104' to parameter: 1
[java] 2859 [main] DEBUG org.hibernate.jdbc.AbstractBatcher - about to open ResultSet (open ResultSets: 0, globally: 0)
[java] 2859 [main] DEBUG org.hibernate.loader.Loader - processing result set
[java] 2859 [main] DEBUG org.hibernate.loader.Loader - result set row: 0
[java] 2859 [main] DEBUG org.hibernate.loader.Loader - result row: EntityKey[com.bea.medrec.domain.Patient#104]
[java] 2859 [main] DEBUG org.hibernate.loader.Loader - Initializing object from ResultSet: [com.bea.medrec.domain.Patient#104]
[java] 2875 [main] DEBUG org.hibernate.persister.entity.BasicEntityPersister - Hydrating entity: [com.bea.medrec.domain.Patient#104]
[java] 2875 [main] DEBUG org.hibernate.type.DateType - returning '17 August 1971' as column: dob1_0_
[java] 2875 [main] DEBUG org.hibernate.type.StringType - returning 'Gabrielle' as column: first3_1_0_
[java] 2875 [main] DEBUG org.hibernate.type.StringType - returning 'Female' as column: gender1_0_
[java] 2875 [main] DEBUG org.hibernate.type.StringType - returning 'Spiker' as column: last5_1_0_
[java] 2875 [main] DEBUG org.hibernate.type.StringType - returning 'H' as column: middle6_1_0_
[java] 2875 [main] DEBUG org.hibernate.type.StringType - returning '4151234564' as column: phone1_0_
[java] 2875 [main] DEBUG org.hibernate.type.StringType - returning '333333333' as column: ssn1_0_
[java] 2875 [main] DEBUG org.hibernate.type.IntegerType - returning '101' as column: address9_1_0_
[java] 2875 [main] DEBUG org.hibernate.loader.Loader - done processing result set (1 rows)
[java] 2875 [main] DEBUG org.hibernate.jdbc.AbstractBatcher - about to close ResultSet (open ResultSets: 1, globally: 1)
[java] 2890 [main] DEBUG org.hibernate.jdbc.AbstractBatcher - about to close PreparedStatement (open PreparedStatements: 1, globally: 1)
[java] 2890 [main] DEBUG org.hibernate.jdbc.AbstractBatcher - closing statement
[java] 2890 [main] DEBUG org.hibernate.loader.Loader - total objects hydrated: 1
[java] 2890 [main] DEBUG org.hibernate.engine.TwoPhaseLoad - resolving associations for [com.bea.medrec.domain.Patient#104]
[java] 2890 [main] DEBUG org.hibernate.event.def.DefaultLoadEventListener - loading entity: [com.bea.medrec.domain.Address#101]
[java] 2890 [main] DEBUG org.hibernate.event.def.DefaultLoadEventListener - creating new proxy for entity
[java] 2890 [main] DEBUG org.hibernate.jdbc.JDBCContext - after autocommit
[java] 2890 [main] DEBUG org.hibernate.impl.SessionImpl - after transaction completion
[java] 2890 [main] DEBUG org.springframework.orm.hibernate3.HibernateTemplate - Not closing pre-bound Hibernate Session after HibernateTemplate
[java] java.lang.ClassCastException: java.lang.Integer
[java] at org.hibernate.type.StringType.toString(StringType.java:42)
[java] at org.hibernate.type.NullableType.toLoggableString(NullableType.java:122)
[java] at org.hibernate.pretty.MessageHelper.infoString(MessageHelper.java:68)
[java] at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:143)
[java] at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:79)
[java] at org.hibernate.impl.SessionImpl.internalLoad(SessionImpl.java:655)
[java] at org.hibernate.type.EntityType.resolveIdentifier(EntityType.java:261)
[java] at org.hibernate.type.EntityType.resolve(EntityType.java:286)
[java] at org.hibernate.engine.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:105)
[java] at org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:530)
[java] at org.hibernate.loader.Loader.doQuery(Loader.java:436)
[java] at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:218)
[java] at org.hibernate.loader.Loader.loadEntity(Loader.java:1345)
[java] at org.hibernate.loader.entity.EntityLoader.load(EntityLoader.java:116)
[java] at org.hibernate.loader.entity.EntityLoader.load(EntityLoader.java:101)
[java] at org.hibernate.persister.entity.BasicEntityPersister.load(BasicEntityPersister.java:2471)
[java] at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:351)
[java] at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:332)
[java] at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:113)
[java] at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:167)
[java] at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:79)
[java] at org.hibernate.impl.SessionImpl.get(SessionImpl.java:621)
[java] at org.hibernate.impl.SessionImpl.get(SessionImpl.java:614)
[java] at org.springframework.orm.hibernate3.HibernateTemplate$1.doInHibernate(HibernateTemplate.java:443)
[java] at org.springframework.orm.hibernate3.HibernateTemplate.execute(HibernateTemplate.java:358)
[java] at org.springframework.orm.hibernate3.HibernateTemplate.get(HibernateTemplate.java:437)
[java] at org.springframework.orm.hibernate3.HibernateTemplate.get(HibernateTemplate.java:432)
[java] at com.bea.medrec.dao.orm.HibernatePatientDao.getById(HibernatePatientDao.java:28)
[java] at JdbcPatientDaoTest.testGetById(JdbcPatientDaoTest.java:74)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[java] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
[java] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[java] at java.lang.reflect.Method.invoke(Method.java:585)
[java] at junit.framework.TestCase.runTest(TestCase.java:154)
[java] at junit.framework.TestCase.runBare(TestCase.java:127)
[java] at junit.framework.TestResult$1.protect(TestResult.java:106)
[java] at junit.framework.TestResult.runProtected(TestResult.java:124)
[java] at junit.framework.TestResult.run(TestResult.java:109)
[java] at junit.framework.TestCase.run(TestCase.java:118)
[java] at junit.framework.TestSuite.runTest(TestSuite.java:208)
[java] at junit.framework.TestSuite.run(TestSuite.java:203)
[java] at junit.textui.TestRunner.doRun(TestRunner.java:116)
[java] at junit.textui.TestRunner.doRun(TestRunner.java:109)
[java] at junit.textui.TestRunner.run(TestRunner.java:72)
[java] at JdbcPatientDaoTest.main(JdbcPatientDaoTest.java:289)
[java] 2890 [main] DEBUG org.springframework.jdbc.datasource.DataSourceTransactionManager - Triggering beforeCompletion synchronization
[java] 2890 [main] DEBUG org.springframework.transaction.support.TransactionSynchronizationManager - Removed value [org.springframework.orm.hibernate3.SessionHolder@14b6bed] for key [org.hibernate.impl.SessionFactoryImpl@9aba32] from thread [main]

Name and version of the database you are using:
PointBase & MySQL

Debug level Hibernate log excerpt:
Complete log:
http://www.firestruck.com/temp/test.out

both of your identifiers are integers. when you call Session.get, are you passing a String as the second parameter?

Resolved.

The issue was with the Patient-User association. The assoication is one-to-one, but does not share a common identifier. Rather, the association is linked via foreign key. Because Patent.Id is an integer and User.Username is a string, a type conflict arouse.

For one-to-one associations via a foreign key, the objects must be mapped using the many-to-one and one-to-one configurations.

A better explanation can be found here:
http://www.informit.com/guides/content.asp?g=java&seqNum=148&rl=1 (see "One-to-One Relationship").