Jakarta Struts Cookbook

4.4. Sorting HTML Tables

Problem

You need to sort the results of a displayed table by clicking on a column header.

Solution

Create an Action, as shown in Example 4-8, that uses the BeanComparator class of the Jakarta Commons BeanUtils library to sort the underlying Collection.

Example 4-8. Sorting tabular data with an Action

package com.oreilly.strutsckbk.ch04; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.List; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.beanutils.BeanComparator; import org.apache.commons.collections.comparators.ReverseComparator; import org.apache.struts.action.Action; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; public class ViewForecastAction extends Action { public ActionForward execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { // create the weather bean WeeklyWeather weather = new WeeklyWeather( ); // create a list to hold the forecast List list = new ArrayList( ); list.addAll( weather.getWeekForecast( ) ); // get the sort by request param String sortBy = request.getParameter("sortBy"); // get the reverse request param boolean reverse = false; String reverseParam = request.getParameter("reverse"); if (reverseParam != null) reverse = Boolean.valueOf(reverseParam).booleanValue( ...