DataControl and Java Generics

I tried to make DataControl from SessionBean:
@Stateless(name="SessionEJB")
public class SessionEJBBean implements SessionEJB, SessionEJBLocal {
@PersistenceContext(unitName="ExampleUnit")
private Entity Manager em;
public SessionEJBBean() {
public List<Employees> getAll(Employees p) {
return null;
public Result<Employees> getResult(Employees parametar) {
return null;
But my GENERIC type Result<T>, in the second method, caused problems.
When I remove this method, everything work just fine.
Is this a BUG, or I'm doing something wrong ?
ERROR:
java.lang.NullPointerException
     at oracle.adfdtinternal.model.ide.managers.BeanManager.findOrCreateBean(BeanManager.java:70)
     at oracle.adfdtinternal.model.ide.managers.BeanManager.findOrCreateBean(BeanManager.java:53)
     at oracle.adfdtinternal.model.ide.objects.builders.StructureDefinitionBuilder.build(StructureDefinitionBuilder.java:628)
     at oracle.adfdtinternal.model.ide.objects.builders.StructureDefinitionBuilder.generateXmlIfNecessary(StructureDefinitionBuilder.java:293)
     at oracle.adfdtinternal.model.ide.objects.builders.StructureDefinitionBuilder.buildMethods(StructureDefinitionBuilder.java:416)
     at oracle.adfdtinternal.model.ide.objects.builders.StructureDefinitionBuilder$1.runHandlingExceptions(StructureDefinitionBuilder.java:647)
     at oracle.adfdt.jdev.transaction.JDevTransactionManager$1.performTask(JDevTransactionManager.java:54)
     at oracle.bali.xml.model.task.StandardTransactionTask.runThrowingXCE(StandardTransactionTask.java:172)
     at oracle.bali.xml.model.task.StandardTransactionTask.run(StandardTransactionTask.java:103)
     at oracle.adfdt.jdev.transaction.JDevTransactionManager.runTaskUnderTransaction(JDevTransactionManager.java:43)
     at oracle.adfdtinternal.model.ide.objects.builders.StructureDefinitionBuilder.build(StructureDefinitionBuilder.java:653)
     at oracle.adfdtinternal.model.ide.objects.builders.JSR227BeanXmlBuilder.build(JSR227BeanXmlBuilder.java:32)
     at oracle.adfdtinternal.model.ide.adapter.AdapterDCHelper.addCreatableTypes(AdapterDCHelper.java:175)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java:585)
     at oracle.adfdt.model.datacontrols.JUDTAdapterDataControl.internalRefreshStructure(JUDTAdapterDataControl.java:624)
     at oracle.adfdt.model.datacontrols.JUDTAdapterDataControl.refreshStructure(JUDTAdapterDataControl.java:275)
     at oracle.adfdtinternal.model.ide.factories.adapter.DCFactoryAdapter.createDataControl(DCFactoryAdapter.java:365)
     at oracle.adfdtinternal.model.ide.factories.adapter.DCFactoryAdapter.createDataControl(DCFactoryAdapter.java:236)
     at oracle.adfdtinternal.model.ide.ProjectCompileListener.invokeFactory(DataControlFactoryMenuListener.java:250)
     at oracle.adfdtinternal.model.ide.DataControlFactoryMenuListener.handleCreateDataControl(DataControlFactoryMenuListener.java:207)
     at oracle.adfdtinternal.model.ide.DataControlFactoryMenuListener.mav$handleCreateDataControl(DataControlFactoryMenuListener.java:35)
     at oracle.adfdtinternal.model.ide.DataControlFactoryMenuListener$1.run(DataControlFactoryMenuListener.java:141)
     at oracle.ide.dialogs.ProgressBar.run(ProgressBar.java:615)
     at java.lang.Thread.run(Thread.java:595)

Hi,
I tried the usecase with POJOs
package pojo;
import java.util.ArrayList;
public class SessionFacade {
    ArrayList<Employees> al = new ArrayList<Employees>();
    public SessionFacade() {
        Employees e1 = new Employees();
        e1.setAge(2);
        e1.setFirstname("Hello");
        e1.setName("Test");
        al.add(e1);
    public void setAl(ArrayList<Employees> al) {
        this.al = al;
    public ArrayList<Employees> getAl() {
        return al;
package pojo;
public class Employees {
String name;
String firstname;
int age;
    public Employees() {
    public void setName(String name) {
        this.name = name;
    public String getName() {
        return name;
    public void setFirstname(String firstname) {
        this.firstname = firstname;
    public String getFirstname() {
        return firstname;
    public void setAge(int age) {
        this.age = age;
    public int getAge() {
        return age;
}with no errors
Frank

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Hello and welcome to the Sun Java forums.
The behavior you describe would not occur if your setX(?) method used T instead of another type constraint.
However, let's look at why it works!
At line 1 in main, you create your Test with a type parameter of Integer; this becomes the type variable T for that particular instance of Test. The only constraint is that the type extends/implements Number, which Integer does.
At line 2 you obtain a reference to a Number, which is what getX() is guaranteed to return. toString() is called on that object, etc.
At line 3 you set the Number in the Test to a Double, which fits the type constraint U extends Number, as well as the type constraint T extends Number which is unused (!). Note that using a different type constraint for U, such as U extends Object or U super Number, could cause a compile-time error.
At line 4 you obtain a reference to a Number, which is what getX() is guaranteed to return.
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x=y;s
Edited by: Looce on Nov 15, 2008 7:15 PM

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null

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ShubhaPradeep wrote:
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DataControl and Java Generics

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