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type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception javax.servlet.ServletException
 org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:516)
 org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:423)
 org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:226)
 org.apache.struts.action.ActionServlet.process(ActionServlet.java:1164)
 org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:415)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
root cause java.lang.NullPointerException
 booksystem1.BuyAction.execute(BuyAction.java:24)
 org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:421)
 org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:226)
 org.apache.struts.action.ActionServlet.process(ActionServlet.java:1164)
 org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:415)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
 javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.9 logs