public class ProductBean extends BaseBean {
   //the product id
   private String id ;
   
   //the product name
   private String name;
   
   //the product description
   private String description;
   
   //the product price
   private double price;
   
   //the product width
   private double width;
   
   //the product height
   private double height;
   
   //the category ids associated with the product
   private Set productCategories;
   
   //the category id selected by the user on the page
   private List selectedCategoryIds;
.
.
.
.
.
public Set getCategoryIds() {
      return this.productCategories;
   }
   
   public void setCategoryIds(Set newCategoryIds) {
      this.productCategories = newCategoryIds;
      
      if (this.productCategories != null) {
         this.selectedCategoryIds = ViewUtils.convertToList(this.productCategories);
      }
   }
   
   public List getSelectedCategoryIds() {
      return this.selectedCategoryIds;
   }
   
   public void setSelectedCategoryIds(List newSelectedCategoryIds) {
      this.selectedCategoryIds = newSelectedCategoryIds;
      this.productCategories = ViewUtils.convertToSet(selectedCategoryIds);
   }

public class ProductListBean extends BaseBean {
   
   private static final int DEFAULT_PRODUCTS_PER_PAGE = 6;
   
   
   private List productBeans;
   
   
   private List currentProductBeans;
   
   
   private Map productBeansMap;
   
   
   private String currentCategoryId;
   
   
   private String currentCategoryName;
   

   private int productsPerPage;
   
      private int totalPages;
   
   
   private int pageNo;
   
   
   public ProductListBean() {
      this.productBeans = new ArrayList();
      this.currentProductBeans = new ArrayList();
      this.productBeansMap = new HashMap();
      
      this.logger.debug("ProductListBean is created");
   }
   
   
   protected void init() {
      try {
         List products = this.serviceLocator.getCatalogService().getAllProducts();
         //getCatalogService().getAllProducts();
         log.info("products size = " + products.size());
         for (int i=0; i<products.size(); i++) {
            Product product = (Product)products.get(i);
            
            ProductBean productBean = ProductBuilder.createProductBean(product);
            productBean.setServiceLocator(this.serviceLocator);
            
            this.productBeans.add(productBean);
         }
         
         this.currentProductBeans = this.productBeans;
         
         this.setProductsPerPage();
         
         this.buildProductBeansMap();
      } catch (Exception e) {
         String msg = "Could not initialize ProductListBean";
         log.info("Could not initialize ProductListBean", e);
         throw new FacesException(msg, e);
      }
      
      this.log.info("ProductListBean is initialized"+currentProductBeans);
   }

public String searchByCategoryAction() {
      this.currentCategoryId = FacesUtils.getRequestParameter(RequestParamNames.CATEGORY_ID);
      String pageNoString = FacesUtils.getRequestParameter(RequestParamNames.PAGE_NO);
      
      try {
         this.pageNo = Integer.parseInt(pageNoString);
      } catch (Exception e) {
         this.pageNo = 1;
      }
      
      this.totalPages = 0;
      
      this.currentProductBeans = new ArrayList();
      
      this.logger.debug("searchByCategoryAction is invoked");
      log.info("categoryId = " + this.currentCategoryId);
      log.info("pageNo = " + this.pageNo);
      
      if (this.currentCategoryId == null || this.currentCategoryId.equals("")) {
         //get all products, no pagination
         this.currentProductBeans = this.productBeans;
      
         return NavigationResults.PRODUCT_LIST;
      }
      else {
         //catalog
      
         Map categoryProductBeans = (Map)this.productBeansMap.get(currentCategoryId);
         log.info("categoryProductBeans Map = " + categoryProductBeans);
         if (categoryProductBeans != null) {
            this.totalPages = categoryProductBeans.size();
            log.info("total pages = " + this.totalPages);
            List productBeans = (List)categoryProductBeans.get(new Integer(this.pageNo));
            log.info("List productbeans = " + this.productBeans.size());
            if (productBeans != null) {
               this.currentProductBeans = productBeans;
            }
         }
         
         log.info("currentProductBeans size = " + this.currentProductBeans.size());
         
         //set current category name
         this.currentCategoryName = FacesUtils.getApplicationBean().getCategoryName(this.currentCategoryId);
         log.info("currentCategoryName = " + this.currentCategoryName);
         
         return NavigationResults.CATALOG;
      }
   }
private void buildProductBeansMap() {
      log.info("buildProductBeansMap is invoked");
      
      this.productBeansMap = new HashMap();
      
      Map categoryProductsMap = new HashMap();
      
      for (int i=0; i<this.productBeans.size(); i++) {
         ProductBean product = (ProductBean)this.productBeans.get(i);
         log.info("product_buildMap"+product.getId());
         Set categoryIds = product.getCategoryIds();
         log.info("product_categoryIds"+categoryIds);
         Iterator ite = categoryIds.iterator();
         while (ite.hasNext()) {
            String categoryId = (String)ite.next();
            
            if (! categoryProductsMap.containsKey(categoryId)) {
               //new category
               List list = new ArrayList();
               list.add(product);
               categoryProductsMap.put(categoryId, list);
            }
            else {
               List list = (List) categoryProductsMap.get(categoryId);
               list.add(product);
            }
         }
      }
      
      Iterator ite = categoryProductsMap.keySet().iterator();
      
      while (ite.hasNext()) {
         Object category = ite.next();
         
         List productBeans = (List)categoryProductsMap.get(category);
         this.productBeansMap.put(category, this.pagination

2009-06-23 11:37:50,173: buildProductBeansMap is invoked
2009-06-23 11:37:50,173: product_buildMapL001
2009-06-23 11:37:50,173: product_categoryIds[]
2009-06-23 11:37:50,173: product_buildMapL002
2009-06-23 11:37:50,173: product_categoryIds[]
2009-06-23 11:37:50,173: product_buildMapL003
2009-06-23 11:37:50,173: product_categoryIds[]
2009-06-23 11:37:50,173: product_buildMapL004
2009-06-23 11:37:50,173: product_categoryIds[]
2009-06-23 11:37:50,173: product_buildMapL005
2009-06-23 11:37:50,173: product_categoryIds[]
2009-06-23 11:37:50,173: product_buildMapL006
2009-06-23 11:37:50,173: product_categoryIds[]
2009-06-23 11:37:50,173: product_buildMapL007
2009-06-23 11:37:50,173: product_categoryIds[]
2009-06-23 11:37:50,173: product_buildMapL008
2009-06-23 11:37:50,173: product_categoryIds[]
2009-06-23 11:37:50,173: ProductListBean is initialized[id=L001 name=Product1, id=L002 name=Product2, id=L003 name=Product3, id=L004 name=Product4, id=L005 name=Product5, id=L006 name=Product6, id=L007 name=Product7, id=L008 name=Product8]
2009-06-23 11:37:50,173: service locator is set
2009-06-23 11:37:50,173: categoryId = 1
2009-06-23 11:37:50,173: pageNo = 1
2009-06-23 11:37:50,173: categoryProductBeans Map = null
2009-06-23 11:37:50,173: currentProductBeans size = 0
2009-06-23 11:37:50,173: currentCategoryName = null

import java.util.Set;
import java.util.HashSet;
import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;


public class ViewUtils {
   /**
    * Convert a list to a set.
    *
    * @param orig the list to be converted
    * @return the set converted from the list
    */
   public static Set convertToSet(List orig) {
      Set result = new HashSet();
      
      if (orig != null) {
         Iterator ite = orig.iterator();
         
         while (ite.hasNext()) {
            result.add(ite.next());
         }
      }
      
      return result;
   }
   
   /**
    * Convert a set to a list.
    * @param orig the set to be converted
    * @return the list converted from the set
    */
   public static List convertToList(Set orig) {
      List result = new ArrayList();
      
      if (orig != null) {
         Iterator ite = orig.iterator();
         
         while (ite.hasNext()) {
            result.add(ite.next());
         }
      }
      
      return result;
   }
}