Strange serialization error when dynamically adding component to column

[Simon Kitching]

Hi,

I'm trying to implement a custom UIColumn that shows a checkbox against 
each row that the user can check to select multiple rows. Due to issue 
MYFACES-781 I can't handle decode directly in this class (UIColumns 
don't get any decode callbacks) so I instead want to add a dummy 
component as a child of my custom column:

public class HtmlRowSelector extends UIColumn {
    public static class SelectBoolean extends UIInput {
        public void decode(FacesContext context) {
            log.debug("decode called. id=" + getClientId(context));
            // more stuff to be added later
        }
    }

    public HtmlRowSelector() {
        setRendererType(DEFAULT_RENDERER_TYPE);

        UIComponent child = new SelectBoolean();
        this.getChildren().add(child);
    }
    ...
    // override encodeChildren to render a checkbox per row
}


This component renders fine when the page is first viewed. However on 
first postback I get:

java.lang.IndexOutOfBoundsException: Index: 1, Size: 1
        at java.util.ArrayList.RangeCheck(ArrayList.java:547)
        at java.util.ArrayList.get(ArrayList.java:322)
	at 
javax.faces.component.UIComponentBase.processRestoreState(UIComponentBase.java:499)
	at 
javax.faces.component.UIComponentBase.processRestoreState(UIComponentBase.java:502)
	at 
javax.faces.component.UIComponentBase.processRestoreState(UIComponentBase.java:502)
	at 
javax.faces.component.UIComponentBase.processRestoreState(UIComponentBase.java:502)
	at 
javax.faces.component.UIComponentBase.processRestoreState(UIComponentBase.java:502)
	at 
javax.faces.component.UIComponentBase.processRestoreState(UIComponentBase.java:502)
	at 
org.apache.myfaces.application.jsp.JspStateManagerImpl.restoreComponentState(JspStateManagerImpl.java:155)
	at 
org.apache.myfaces.application.jsp.JspStateManagerImpl.restoreView(JspStateManagerImpl.java:211)
	at 
org.apache.myfaces.application.jsp.JspViewHandlerImpl.restoreView(JspViewHandlerImpl.java:255)
	at 
org.apache.myfaces.application.jsp.JspTilesViewHandlerImpl.restoreView(JspTilesViewHandlerImpl.java:320)
	at 
org.apache.myfaces.lifecycle.LifecycleImpl.restoreView(LifecycleImpl.java:139)


Any idea what I might be doing wrong? Commenting out the line
        this.getChildren().add(child);
makes the exception go away, though of course I then can't get any 
decode callbacks.

NB: I've tried marking the new child as transient, as there really isn't 
any state for the child to save but that doesn't help; an exception is 
thrown in the table decoding instead. I've provided a decode 
implementation in SelectBoolean which just calls super.decode and logs a 
message; that method is completing fine - ie it's not the SelectBoolean 
class decode method that's causing the exception *directly*.


All hints/suggestions/guesses/alternatives very gratefully received!


Thanks,

Simon