title: Need to set the quartz cron expression dynamically
body: <p>I'm using quartz in my web application (Servlet web app) following is snap of quartz.property file and the quartz.job.xml </p>
  
  <p>quartz.property</p>
  
  <pre><code>#===================================================
  # Configure the Job Initialization Plugin
  #===================================================
  
  org.quartz.plugin.jobInitializer.class = org.quartz.plugins.xml.XMLSchedulingDataProcessorPlugin
  org.quartz.plugin.jobInitializer.fileNames = jobs.xml
  org.quartz.plugin.jobInitializer.failOnFileNotFound = true
  org.quartz.plugin.jobInitializer.scanInterval = 10
  org.quartz.plugin.jobInitializer.wrapInUserTransaction = false
  
  
  &lt;?xml version='1.0' encoding='utf-8'?&gt;
  &lt;job-scheduling-data xmlns="http://www.quartz-scheduler.org/xml/JobSchedulingData"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.quartz-scheduler.org/xml/JobSchedulingData http://www.quartz-scheduler.org/xml/job_scheduling_data_1_8.xsd"
    version="1.8"&gt;
  
      &lt;schedule&gt;
          &lt;job&gt;
              &lt;name&gt;my-very-clever-job&lt;/name&gt;
              &lt;group&gt;MYJOB_GROUP&lt;/group&gt;
  
              &lt;description&gt;The job description&lt;/description&gt;
              &lt;job-class&gt;com.acme.scheduler.job.ReportJob&lt;/job-class&gt;
          &lt;/job&gt;
  
          &lt;trigger&gt;
              &lt;cron&gt;
                  &lt;name&gt;my-trigger&lt;/name&gt;
                  &lt;group&gt;MYTRIGGER_GROUP&lt;/group&gt;
                  &lt;job-name&gt;my-very-clever-job&lt;/job-name&gt;
  
                  &lt;job-group&gt;MYJOB_GROUP&lt;/job-group&gt;
                  &lt;!-- trigger every night at 4:30 am --&gt;
                  &lt;cron-expression&gt;0 30 4 * * ?&lt;/cron-expression&gt;
  
              &lt;/cron&gt;
          &lt;/trigger&gt;
      &lt;/schedule&gt;
  &lt;/job-scheduling-data&gt;
  </code></pre>
  
  <p>Every thing work fine,in this order. I need to allow user to change the time (cron expression) as the way they want.My question is how do i set the cron expression in dynamically.</p>