diff -r 41a66a42791b -r 31822b475baa src/share/classes/com/sun/codemodel/internal/JDefinedClass.java
--- a/src/share/classes/com/sun/codemodel/internal/JDefinedClass.java	Mon Mar 09 13:34:04 2009 -0700
+++ b/src/share/classes/com/sun/codemodel/internal/JDefinedClass.java	Mon Apr 20 15:14:39 2009 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright 2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * Copyright 2005-2006 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -251,6 +251,13 @@
         if (superClass == null)
             throw new NullPointerException();
 
+        for( JClass o=superClass.outer(); o!=null; o=o.outer() ){
+            if(this==o){
+                throw new IllegalArgumentException("Illegal class inheritance loop." +
+                "  Outer class " + this.name + " may not subclass from inner class: " + o.name());
+            }
+        }
+
         this.superClass = superClass;
         return this;
     }
@@ -307,8 +314,9 @@
     }
 
     /**
-     * This method generates reference to the JEnumConstant in
-     * the class
+     * If the named enum already exists, the reference to it is returned.
+     * Otherwise this method generates a new enum reference with the given
+     * name and returns it.
      *
      * @param name
      *          The name of the constant.
@@ -316,8 +324,11 @@
      *      The generated type-safe enum constant.
      */
     public JEnumConstant enumConstant(String name){
-        JEnumConstant ec = new JEnumConstant(this, name);
-        enumConstantsByName.put(name, ec);
+        JEnumConstant ec = enumConstantsByName.get(name);
+        if (null == ec) {
+            ec = new JEnumConstant(this, name);
+            enumConstantsByName.put(name, ec);
+        }
         return ec;
     }
 
@@ -417,7 +428,6 @@
      *      newly created Annotation Type Declaration
      * @exception JClassAlreadyExistsException
      *      When the specified class/interface was already created.
-
      */
     public JDefinedClass _annotationTypeDeclaration(String name) throws JClassAlreadyExistsException {
         return _class (JMod.PUBLIC,name,ClassType.ANNOTATION_TYPE_DECL);
@@ -576,7 +586,6 @@
      *      null if not found.
      */
     public JMethod getMethod(String name, JType[] argTypes) {
-        outer :
         for (JMethod m : methods) {
             if (!m.name().equals(name))
                 continue;
@@ -740,8 +749,8 @@
             f.nl().g(jdoc);
 
         if (annotations != null){
-            for( int i=0; i<annotations.size(); i++ )
-                f.g(annotations.get(i)).nl();
+            for (JAnnotationUse annotation : annotations)
+                f.g(annotation).nl();
         }
 
         f.g(mods).p(classType.declarationToken).id(name).d(generifiable);