Time for action – using the MultiSelectListbox component

Let us see how to create a MultiSelectListbox component to display categories and its subcategories based on the selected category, by performing the following steps:

1. Instantiate List<SelectItem> instances with details of categories and subcategories:

   public class CatalogController 
   {
       private List<SelectItem> categories;    
       private String selectedCategory;
   
       public CatalogController() 
       {        
           categories = new ArrayList<SelectItem>();
   
           SelectItemGroup homeAppliancesGrp = new SelectItemGroup("Home Appliances");
           SelectItemGroup homeDecorGrp = new SelectItemGroup("Home & Decor");
           SelectItem clocks = new SelectItem("Wall Clocks");
           SelectItem candleHolders = new SelectItem("Candle Holders");
           SelectItem artPrints = new SelectItem("Art Prints");
           homeDecorGrp.setSelectItems(new SelectItem[...