edit p:datatable whth String ArrayList - jsf

Question

i have this problem: if build a p:datatable from ArrayList it's impossible editing and sometimes rowSelectd not fire.
my xhtml code:
<h:form id="form">
<p:messages id="messageWiz" showDetail="true" closable="true" autoUpdate="true"/>
<h:panelGroup>
<p:commandButton id="addPattern" icon="ui-icon-add"
actionListener="#{testController.add}" process="#this"
update="patternsId" />
<p:commandButton id="deletePattern" icon="ui-icon-delete"
actionListener="#{testController.remove}"
process="#this" update="#this, patternsId"
disabled="#{empty testController.patternsSelected}" />
</h:panelGroup>
<p:dataTable id="patternsId" var="pattern" scrollable="true" scrollHeight="200"
value="#{testController.patterns}" editable="true"
editMode="cell" widgetVar="patterns" rowIndexVar="idx"
selection="#{testController.patternsSelected}"
rowKey="#{pattern}"
emptyMessage="#{label['msg.emptytable']}" styleClass="nofooter">
<p:ajax event="rowSelect" update=":form:deletePattern" />
<p:ajax event="rowUnselect" update=":form:deletePattern" />
<p:ajax event="rowSelectCheckbox" update=":form:deletePattern"/>
<p:ajax event="toggleSelect" update=":form:deletePattern" />
<p:ajax event="rowUnselectCheckbox" update=":form:deletePattern" />
<p:ajax event="cellEdit" update=":form:messageWiz" />
<p:column selectionMode="multiple" width="20" />
<p:column>
<p:cellEditor>
<f:facet name="output">
<h:outputText value="#{pattern}" />
</f:facet>
<f:facet name="input">
<p:inputText value="#{pattern}"
required="true" style="width:96%" autocomplete="off" />
</f:facet>
</p:cellEditor>
</p:column>
</p:dataTable>
</h:form>
controller code:
#ManagedBean
#ViewScoped
public class TestController implements Serializable {
private static final long serialVersionUID = 1L;
private ArrayList<String> patterns = new ArrayList<String>();
private ArrayList<String> patternsSelected;
public ArrayList<String> getPatterns() {
return patterns;
}
public void setPatterns(ArrayList<String> patterns) {
this.patterns = patterns;
}
public ArrayList<String> getPatternsSelected() {
return patternsSelected;
}
public void setPatternsSelected(ArrayList<String> patternsSelected) {
this.patternsSelected = patternsSelected;
}
public void add() {
patterns.add(new String());
}
public void remove() {
}
}
add row and edit, then close edit end inputed vaues disappear, rowSelected not fire.

Answer 1

You cannot achieve this with an arraylist of strings.
You must implement a list of Pattern objects (with at least id and value members)
Backing bean (testController) must implement SelectableDataModel (unique ids will help to be sure to identify and remove the right items).