Custom component with children - Child component added at end appears as first child when rendered.

[Keerthi P]

I have a custom JSF component that renders navigation links. The following is a typical usage of the component:

 
<custom:navigationBar id="navbar" spacing="2" actionListener="#{testBean.navigationLinkClicked}" immediate="true" binding="#{testBean.navigationBar}">
	<custom:navigationLink id="primaryData" value="Primary Data"/>
	<custom:navigationLink id="principals" value="Principals" active="true"/>
	<custom:navigationLink id="administrators" value="Administrators"/>
	<custom:navigationLink id="custodians" value="Custodians"/>
	<custom:navigationLink id="accountingFirms" value="Accounting Firms" clickable="false"/>
	<custom:navigationLink id="lawFirms" value="Law Firms" clickable="false"/>
	<custom:navigationLink id="billing" value="Billing" clickable="false"/>
</custom:navigationBar>

And, the rendered content will appear as following, similar to the navigation links at the top of this page:

Primary Data | Principals | Administrators | Custodiams | Accounting Firms | Law Firms | Billing

As you notice, the navigationBar component is bounded to #{testBean.navigationBar} which is defined as below in the Backing bean:

 

public class TestBean {

	private HtmlNavigationBar navigationBar;

        ....

	public String formSubmitted() {
		HtmlNavigationLink link = new HtmlNavigationLink();
		link.setId("link");
		link.setValue("New link");

		navigationBar.getChildren().add(link)

		return null;
	}

The backing bean has an action method formSubmitted() that adds a child (HtmlNavigationLink) component to the parent (HtmlNavigationBar) dynamically. I thought that this newly added child would be the last child (as it is added to end of the children list). But, when the navigationBar renders its children, the HtmlNavigationLink 'New link' appears as the first child causing the content rendered as below:

New Link | Primary Data | Principals | Administrators | Custodiams | Accounting Firms | Law Firms | Billing

The following is the encodeChildren() method of HtmlNavigationBar

	@Override
	public void encodeChildren(FacesContext context) throws IOException {
		ResponseWriter writer = context.getResponseWriter();
		List<UIComponent> children = getChildren();
		int count = children.size();

		for (int i = 0; i < count; i++) {
			UIComponent child = children.get(i); // -- why does 'New link' appear at index == 0?
			if (child instanceof HtmlNavigationLink) {
				child.encodeAll(context);
			}
		}
	}

As noted in the comment above, while the link was added to the end of the list in the action method, it appears at index position 0 as the first child? Why is it so?

[Samuel March]

java.util.List uses and enumerator , also you may need to sort a list.



do your for loop with this

Object[] childobjs = children.toArray();
UIComponent child;
for (int i = 0; i < childobjs.length; i++) {   
            child = ((UIComponent)childobjs[i]); // -- why does 'New link' appear at index == 0?   
            if (child instanceof HtmlNavigationLink) {   
                child.encodeAll(context);   
            }   
        }

or

java.util.ListIterator<UIComponent> chlsit = children.listIterator(0); 
UIComponent child;
while(chlsit.hasNext()){
 child = ((UIComponent)chlsit.next()); 
 if (child instanceof HtmlNavigationLink) {   
                child.encodeAll(context);   
}

}// end iterator

[Keerthi P]

    
List<UIComponent> children = getChildren(); 

// loop thru children

is same as

    
List<UIComponent> childrenList = getChildren(); 
Object[] childobjs = childrenList.toArray();  
// loop thru childobjs

[Keerthi P]

I have posted a simplified case of the issue here https://issues.apache.org/jira/browse/MYFACES-2392 and here
https://facelets.dev.java.net/issues/show_bug.cgi?id=358

If anyone has any clue, please advise.