[jboss-user] [JBoss Seam] - UnsupportedOperationException when using h:selectManyListbox

Hi, I receive an UnsupportedOperationException when I try to call entityManager.merge(exam) Here is a part of the stack trace: anonymous wrote : java.util.AbstractList.clear(AbstractList.java:217) | org.hibernate.type.CollectionType.replaceElements(CollectionType.java:445) | org.hibernate.type.CollectionType.replace(CollectionType.java:524) | org.hibernate.type.TypeFactory.replace(TypeFactory.java:482) | org.hibernate.event.def.DefaultMergeEventListener.copyValues(DefaultMergeEventListener.java:340) | org.hibernate.event.def.DefaultMergeEventListener.entityIsPersistent(DefaultMergeEventListener.java:153) | org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:126) | And a part of the JSF code: <h:selectManyListbox id="providerList" value="#{exam.providerList}" styleClass="field" required="true"> | <s:selectItems value="#{providers}" var="p" label="#{p.name}"/> | <s:convertEntity /> | </h:selectManyListbox> Where "providers" is received from a @Factory method and exam.providerList is used with a getter/setter for the property List<Provider> providerList of the Exam entity. I found that setProviderList() is called with an argument of type Arrays$ArrayList which is immutable and does not override AbstractList.remove(). This is the reason for the exception to occur. I wanted to ask if some has seen the same problem and knows the solution. Maybe there is something else that I'm not doing right. I have also found a workaround which I consider very ugly. What I did was to make a modification to setProviderList() so that it recognizes Arrays$ArrayList and create a new ArrayList from it. Any comments? Thanks in advance... View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4079190#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...