Dynamic Category Menu Model

CategoryMenuModel.java

public class CategoryMenuModel implements MenuModel, ActionListener, Serializable {
    
    private static final long serialVersionUID = -2866930830066526910L;
    protected Category category;
    protected List<UIComponent> contents = new ArrayList<>();
    protected static UIViewRoot uiViewRoot = new UIViewRoot();
    
    public Category getCategory() {
        return category;
    }
    
    // Creates and adds the MenuItems to the Menu
    public void setCategory(Category category) throws IOException {
        this.category = category;
        resetContents();
        for(Category childCategory : category.getChildCategories()) {
            MenuItem subCategoryItem = new MenuItem();
            subCategoryItem.setValue(childCategory.getName());
            subCategoryItem.setId(uiViewRoot.createUniqueId());
            subCategoryItem.setAjax(false);
            subCategoryItem.getAttributes().put("category", childCategory);
            subCategoryItem.addActionListener(this);
            addMenuItem(subCategoryItem);
        }
    }
    
    // Gets called when a MenuItem is clicked. The clicked MenuItem becomes the new top level MenuItem.
    @Override
    public void processAction(ActionEvent event)
            throws AbortProcessingException {
        if(event.getSource().getClass() == MenuItem.class) {
             MenuItem sourceItem = (MenuItem) event.getSource();
             Category newCategory = (Category) sourceItem.getAttributes().get("category");
             setCategory(newCategory);
        }
    }
    
    @Override
    public List<UIComponent> getContents() {
        return contents;
    }

    @Override
    public void addSubmenu(Submenu submenu) {
        contents.add(submenu);
    }

    @Override
    public void addMenuItem(MenuItem menuItem) {
        contents.add(menuItem);
    }
    
    protected void resetContents() {
        contents = new ArrayList<UIComponent>();
    }
}