Help diagnosing java.lang.IllegalArgumentException

Question

Hello,
I have an Eclipse RCP desktop app that I have been working on for the past few months, without incident. In the process of upgrading to the standard com.sleepycat.je version "4.0.92" plugin in Eclipse 3.5, I am getting the exception below. When I try to back up to the older version, it does not matter, the exception below will not go away. The class in question is in the application's codebase, and I see the .class in the bin tree.
I am using the DPL assistant (latest update from this site).
In addition, this is not a web app, but rather a desktop app. I have checked the runtime classpath to confirm that the class is indeed there. When I access the same code from a unit test project inside the same workspace, I do not see this exception.
I am happy to attach/upload anything that would provide any information needed to help me diagnose this problem.
My class declaration is below the exception.
java.lang.IllegalArgumentException: Class could not be loaded or is not an entity class: com.patholase.core.entity.Patient
     at com.sleepycat.persist.impl.Store.checkEntityClass(Store.java:1391)
     at com.sleepycat.persist.impl.Store.getPrimaryIndex(Store.java:316)
     at com.sleepycat.persist.EntityStore.getPrimaryIndex(EntityStore.java:308)
     at com.patholase.core.entity.mgr.PatientManager.<init>(PatientManager.java:59)
     at com.patholase.core.entity.mgr.PatientManager.<clinit>(PatientManager.java:27)
     at com.patholase.g3.system.SystemInitializer.initDataStore(SystemInitializer.java:78)
     at com.patholase.g3.system.SystemInitializer.init(SystemInitializer.java:42)
     at com.patholase.g3.product.Application.start(Application.java:25)
     at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:194)
     at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
     at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
     at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:367)
     at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
     at java.lang.reflect.Method.invoke(Unknown Source)
     at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:611)
     at org.eclipse.equinox.launcher.Main.basicRun(Main.java:566)
     at org.eclipse.equinox.launcher.Main.run(Main.java:1363)
======= class
package com.acme.core.entity;
import static com.sleepycat.persist.model.Relationship.ONE_TO_MANY;
import static com.sleepycat.persist.model.Relationship.MANY_TO_ONE;
import static com.sleepycat.persist.model.DeleteAction.NULLIFY;
import com.sleepycat.persist.model.Entity;
import com.sleepycat.persist.model.PrimaryKey;
import com.sleepycat.persist.model.SecondaryKey;
import java.util.Date;
import java.util.Set;
import java.util.HashSet;
@Entity public class Patient implements java.io.Serializable {
     public static final long serialVersionUID = 1L;
@PrimaryKey(sequence="ID")
public long id;
     public String firstName;
     public String lastName;
     public Date DOB;
     public String internalPracticeId;// internal to practice
     // for tree view
     public Object parent;
     public Patient(){
     public Patient(String firstName, String lastName)
     this.firstName = firstName;
     this.lastName = lastName;
     public String getFirstName() {
          return firstName;
     public void setFirstName(String firstName) {
          this.firstName = firstName;
     public String getLastName() {
          return lastName;
     public void setLastName(String lastName) {
          this.lastName = lastName;
     public long getId() {
          return id;
     public void setId(long id) {
          this.id = id;
     public Date getDOB() {
          return DOB;
     public void setDOB(Date dob) {
          DOB = dob;
     public Object getParent() {
          return parent;
     public void setParent(Object parent) {
          this.parent = parent;
     public String getInternalPracticeId() {
          return internalPracticeId;
     public void setInternalPracticeId(String internalPracticeId) {
          this.internalPracticeId = internalPracticeId;
     public String nameTreeString(){
          return " [" + this.internalPracticeId + "] " + lastName + ", "+ firstName;
     public String toString()
     return "[PatientData: id=" + id + " lastName=" + lastName +
                    " firstName=" + firstName + " DOB= " + DOB + ']';
}

Answer 1

I think you have interpreted the exception message correctly, but just to be sure, such an exception means that the Patient class cannot be found when getPrimaryIndex() is called. That means that either the class does not have the @Entity annotation, or that there is a classloader/classpath issue. Your code shows that @Entity is there, so it must be a classpath issue.
Since it seems to have happened around the upgrade, presumably it did something unexpected to your classpath settings. When you say that you have checked your runtime classpath, do you mean your project's build path/library variables? Would printing the program's classpath from within JAVA by displaying the java.class.path system variable give a hint? Perhaps checking to see if you have the expected JE version (system.out.println(com.sleepycat.je.JEVersion.CURRENT_VERSION)) would help debug. The JE version shouldn't be an issue, but if your code sees an unexpected JE version, it might tell you something.
There is always the last option of creating a new Eclipse workspace and creating a new project, which points at this code. I did that once when an Eclipse project stopped working for unknown reasons (not with this sort of problem) as a debugging step.