DDL generation from Entity with CollectionOfElements

ironic · **Joined:** Wed Jan 24, 2007 3:37 pm **Posts:** 4

I have a class, let's call it A, that contains a List of class B. Each instance of B has a List of class C. I'm trying to generate the DDL for this, so I've annotated the code and run it through SchemaExport, which throws a ConcurrentModificationException. My environment: Java 1.5, Oracle 10, Hibernate 3.2.1ga.

The problem seems to be caused by having an entity (A) containing an embedded collection (of B), each element of which contains a collection (of C). SchemaExport generates correct DDL when the annotations are modified to make B and/or C an entity, but not when they are both components. I realise this is considered something of an exotic case, but I'd like to know why the DDL doesn't generate.

Here's the Java code:

Code:

@Entity
@Table(name="A")
public class A {
    @Id
    @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="aSequence")
    @SequenceGenerator(name="aSequence", sequenceName="seq_A")
    private int id;
    @CollectionOfElements
    @IndexColumn(name="indx")
    private List<B> listOfB;

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public List<B> getListOfB() {
        return listOfB;
    }
    public void setListOfB(List<B> listOfB) {
        this.listOfB = listOfB;
    }
}

@Embeddable
public class B {
    @CollectionOfElements
    @IndexColumn(name="ndx")
    private List<C> listOfC;

    public List<C> getListOfC() {
        return listOfC;
    }
    public void setListOfC(List<C> listOfC) {
        this.listOfC = listOfC;
    }
}

@Embeddable
public class C {

    @Column(length=500)
    private String comment;

    public String getComment() {
        return comment;
    }
    public void setComment(String comment) {
        this.comment = comment;
    }
}

The code to call SchemaExport:

Code:

public class DBGen {
    /**
    * Simple program to generate the database schema from the
    * Hibernate annotations
    */
    public static void main(String[] args) {
        if (args.length != 1) {
            System.out.println("usage: DBGen <sqlFile>");
            System.exit(-1);
        }
        try {
            Configuration cfg =
                    new AnnotationConfiguration().configure("WEB-INF/hibernate.cfg.xml");
            new SchemaExport(cfg).
                setOutputFile(args[0]).
                setFormat(true).
                setDelimiter(";").
                create(true, false);
            System.exit(0);
        }
        catch (Exception e) {
            e.printStackTrace();
            System.exit(-1);
        }
    }
}

The Hibernate configuration file:

Code:

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD//EN"
    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
  <session-factory>
    <!-- properties -->
    <property name="hibernate.dialect">
      org.hibernate.dialect.Oracle9Dialect
    </property>
    <property name="show_sql">true</property>
    <property name="hibernate.format_sql">true</property>
    <mapping class="A" />
  </session-factory>
</hibernate-configuration>

And finally, the stack trace when I run this:

Code:

java.util.ConcurrentModificationException
   at java.util.AbstractList$Itr.checkForComodification(Unknown Source)
   at java.util.AbstractList$Itr.remove(Unknown Source)
   at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1128)
   at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:296)
   at org.hibernate.cfg.Configuration.generateDropSchemaScript(Configuration.java:756)
   at org.hibernate.tool.hbm2ddl.SchemaExport.<init>(SchemaExport.java:93)
   at org.hibernate.tool.hbm2ddl.SchemaExport.<init>(SchemaExport.java:61)
   at DBGen.main(DBGen.java:20)

Any insight or assistance would be greatly appreciated.

max · **Posted:** Thu Mar 29, 2007 11:22 am

sounds like an error in Annotation Binder.

Create a simple testcase and attach it to annotations jira.