Hi team,
I know it would be silly to ask this but i couldnt get rid of this problem. i am running hbm2ddl task of the build file which throws an exception java.lang.ClassNotFoundException:
oracle.jdbc.driver.OracleDriver but i am pretty sure that the jdbc dirvers (classes12.zip) are on the class path.

I have a hibenate application(standalone) which connects to database in the same project without throwing any exception but when i try to generate schema with ant it throws this exception. Please help me....

hbm2ddl:
[hibernatetool] Executing Hibernate Tool with a Standard Configuration
[hibernatetool] 1. task: hbm2ddl (Generates database schema)
[hibernatetool] (cfg.Environment 474 ) Hibernate 3.1 rc1
[hibernatetool] (cfg.Environment 504 ) hibernate.properties not found
[hibernatetool] (cfg.Environment 520 ) using CGLIB reflection optimizer
[hibernatetool] (cfg.Environment 550 ) using JDK 1.4 java.sql.Timestamp handling
[hibernatetool] (cfg.Configuration 1291) configuring from file: hibernate.cfg.xml
[hibernatetool] (cfg.Configuration 460 ) Reading mappings from resource: Customer.hbm.xml
[hibernatetool] (cfg.HbmBinder 266 ) Mapping class: Customer -> customer
[hibernatetool] (cfg.Configuration 1368) Configured SessionFactory: null
[hibernatetool] (cfg.Configuration 1014) processing extends queue
[hibernatetool] (cfg.Configuration 1018) processing collection mappings
[hibernatetool] (cfg.Configuration 1027) processing association property references
[hibernatetool] (cfg.Configuration 1049) processing foreign key constraints
[hibernatetool] (dialect.Dialect 100 ) Using dialect: org.hibernate.dialect.OracleDialect
[hibernatetool] (cfg.Configuration 1014) processing extends queue
[hibernatetool] (cfg.Configuration 1018) processing collection mappings
[hibernatetool] (cfg.Configuration 1027) processing association property references
[hibernatetool] (cfg.Configuration 1049) processing foreign key constraints
[hibernatetool] (cfg.Configuration 1014) processing extends queue
[hibernatetool] (cfg.Configuration 1018) processing collection mappings
[hibernatetool] (cfg.Configuration 1027) processing association property references
[hibernatetool] (cfg.Configuration 1049) processing foreign key constraints
[hibernatetool] (hbm2ddl.SchemaExport 153 ) Running hbm2ddl schema export
[hibernatetool] (hbm2ddl.SchemaExport 175 ) writing generated schema to file: E:\Java\eclipse\workspace\MyProjects\import\my-schema.ddl
[hibernatetool] (hbm2ddl.SchemaExport 180 ) exporting generated schema to database
[hibernatetool] (connection.DriverManagerConnectionProvider 41 ) Using Hibernate built-in connection pool (not for production use!)
[hibernatetool] (connection.DriverManagerConnectionProvider 42 ) Hibernate connection pool size: 3
[hibernatetool] (connection.DriverManagerConnectionProvider 45 ) autocommit mode: false
[hibernatetool] (connection.DriverManagerConnectionProvider 65 ) JDBC Driver class not found: oracle.jdbc.driver.OracleDriver
[hibernatetool] java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver
[hibernatetool] at org.apache.tools.ant.AntClassLoader.findClassInComponents(AntClassLoader.java:1166)
[hibernatetool] at org.apache.tools.ant.AntClassLoader.findClass(AntClassLoader.java:1107)
[hibernatetool] at org.apache.tools.ant.AntClassLoader.loadClass(AntClassLoader.java:977)
[hibernatetool] at java.lang.ClassLoader.loadClass(Unknown Source)
[hibernatetool] at java.lang.ClassLoader.loadClassInternal(Unknown Source)
[hibernatetool] at java.lang.Class.forName0(Native Method)
[hibernatetool] at java.lang.Class.forName(Unknown Source)
[hibernatetool] at org.hibernate.util.ReflectHelper.classForName(ReflectHelper.java:108)
[hibernatetool] at org.hibernate.connection.DriverManagerConnectionProvider.configure(DriverManagerConnectionProvider.java:61)
[hibernatetool] at org.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:124)
[hibernatetool] at org.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:56)
[hibernatetool] at org.hibernate.tool.hbm2ddl.SchemaExport$ProviderConnectionHelper.getConnection(SchemaExport.java:453)
[hibernatetool] at org.hibernate.tool.hbm2ddl.SchemaExport.execute(SchemaExport.java:181)
[hibernatetool] at org.hibernate.tool.hbm2ddl.SchemaExport.create(SchemaExport.java:133)
[hibernatetool] at org.hibernate.tool.ant.Hbm2DDLExporterTask.execute(Hbm2DDLExporterTask.java:48)
[hibernatetool] at org.hibernate.tool.ant.HibernateToolTask.execute(HibernateToolTask.java:144)
[hibernatetool] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
[hibernatetool] at org.apache.tools.ant.Task.perform(Task.java:364)
[hibernatetool] at org.apache.tools.ant.Target.execute(Target.java:341)
[hibernatetool] at org.apache.tools.ant.Target.performTasks(Target.java:369)
[hibernatetool] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1216)
[hibernatetool] at org.apache.tools.ant.Project.executeTarget(Project.java:1185)
[hibernatetool] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:40)
[hibernatetool] at org.eclipse.ant.internal.ui.antsupport.EclipseDefaultExecutor.executeTargets(EclipseDefaultExecutor.java:32)
[hibernatetool] at org.apache.tools.ant.Project.executeTargets(Project.java:1068)
[hibernatetool] at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.run(InternalAntRunner.java:423)
[hibernatetool] at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.main(InternalAntRunner.java:137)
[hibernatetool] (hbm2ddl.SchemaExport 206 ) schema export unsuccessful
[hibernatetool] org.hibernate.HibernateException: JDBC Driver class not found: oracle.jdbc.driver.OracleDriver
[hibernatetool] at org.hibernate.connection.DriverManagerConnectionProvider.configure(DriverManagerConnectionProvider.java:66)
[hibernatetool] at org.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:124)
[hibernatetool] at org.hibernate.connection.ConnectionProviderFactory.newConnectionProvider(ConnectionProviderFactory.java:56)
[hibernatetool] at org.hibernate.tool.hbm2ddl.SchemaExport$ProviderConnectionHelper.getConnection(SchemaExport.java:453)
[hibernatetool] at org.hibernate.tool.hbm2ddl.SchemaExport.execute(SchemaExport.java:181)
[hibernatetool] at org.hibernate.tool.hbm2ddl.SchemaExport.create(SchemaExport.java:133)
[hibernatetool] at org.hibernate.tool.ant.Hbm2DDLExporterTask.execute(Hbm2DDLExporterTask.java:48)
[hibernatetool] at org.hibernate.tool.ant.HibernateToolTask.execute(HibernateToolTask.java:144)
[hibernatetool] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
[hibernatetool] at org.apache.tools.ant.Task.perform(Task.java:364)
[hibernatetool] at org.apache.tools.ant.Target.execute(Target.java:341)
[hibernatetool] at org.apache.tools.ant.Target.performTasks(Target.java:369)
[hibernatetool] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1216)
[hibernatetool] at org.apache.tools.ant.Project.executeTarget(Project.java:1185)
[hibernatetool] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:40)
[hibernatetool] at org.eclipse.ant.internal.ui.antsupport.EclipseDefaultExecutor.executeTargets(EclipseDefaultExecutor.java:32)
[hibernatetool] at org.apache.tools.ant.Project.executeTargets(Project.java:1068)
[hibernatetool] at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.run(InternalAntRunner.java:423)
[hibernatetool] at org.eclipse.ant.internal.ui.antsupport.InternalAntRunner.main(InternalAntRunner.java:137)
[hibernatetool] Caused by: java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver
[hibernatetool] at org.apache.tools.ant.AntClassLoader.findClassInComponents(AntClassLoader.java:1166)
[hibernatetool] at org.apache.tools.ant.AntClassLoader.findClass(AntClassLoader.java:1107)
[hibernatetool] at org.apache.tools.ant.AntClassLoader.loadClass(AntClassLoader.java:977)
[hibernatetool] at java.lang.ClassLoader.loadClass(Unknown Source)
[hibernatetool] at java.lang.ClassLoader.loadClassInternal(Unknown Source)
[hibernatetool] at java.lang.Class.forName0(Native Method)
[hibernatetool] at java.lang.Class.forName(Unknown Source)
[hibernatetool] at org.hibernate.util.ReflectHelper.classForName(ReflectHelper.java:108)
[hibernatetool] at org.hibernate.connection.DriverManagerConnectionProvider.configure(DriverManagerConnectionProvider.java:61)
[hibernatetool] ... 18 more
(connection.DriverManagerConnectionProvider 147 ) cleaning up connection pool: null
BUILD SUCCESSFUL
Total time: 3 seconds

you need to put oracle.jdbc.driver.OracleDriver in the classpath. i don't know what classes12.zip is supposed to do but this typically is a file that ends with "jar" .

.zip is a .jar and a .jar is a .zip ;)

but since you do get a class not found exception then it is definitly not on the classpath when hbm2ddl is running.

I think it is safe to say Oracle doesn't distribute their drivers this way.

no - oracle *does* distribute classes12.zip. Their newer versions *also* include a *.jar.

they really name it classes12 ? well, it fooled me. I've worked in a 10g shop for about 9 monthes now and I have only seen jars.

go look in 10.1.0\Db_2\jdbc\lib and learn ;)

I usually rename classes12.zip to classes12.jar so you know all class loaders will find it as they don't always pickup a zip extension. The first time classes12.zip was around Oracle8 (from memory) and it was for the Java 1.2 JRE there was also classes11.zip for earlier JREs.

apparently my client has a policy of renaming these to something descriptive ;)