java - Posting to self servlet creating an infinite loop -

i trying develop servlet page display form , user fill in form , post servlet (problem). pasted code below. when call servlet page displayed ok , can fill in form when click submit , post it, programs enters loop mysql insert command runs indefinitely , forced stop program.

the problem seems coming line:

request.getrequestdispatcher("/problem").include(request, response); 

however way see call servlet again after post page somehow creating program loop. idea why case?

below servlet:

@webservlet(description = "problem page", urlpatterns = { "/problem" }) public class problempage extends httpservlet { private static final long serialversionuid = 1l;  /**  * @see httpservlet#httpservlet()  */ public problempage() {     super();     // todo auto-generated constructor stub }      protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {     // todo auto-generated method stub     string problemid = request.getparameter("pbid");     string option = request.getparameter("opt");     string productid = request.getparameter("pdid");      if(problemid==null && option==null && productid==null) {         printwriter out = response.getwriter();          try {             for(string printline:(new problem()).printproblemadd()) {                 out.print(printline);             }         } catch (exception e) {             // todo auto-generated catch block             e.printstacktrace();         }     } else if(problemid!=null && option!=null && productid==null) {         if(option.equals("edit")) {             request.getrequestdispatcher("problem").include(request, response);           } else if(option.equals("del")) {          } else {             printwriter out = response.getwriter();             out.print("<p>page invalid.</p>");         }      } else if(problemid==null && option==null && productid!=null) {         //lists problems product          problem problem = new problem(productid);         printwriter out = response.getwriter();         try {             for(string printline:problem.print()) {                 out.print(printline);             }         } catch (exception e) {             // todo auto-generated catch block             e.printstacktrace();         }     } else {         //page invalid         printwriter out = response.getwriter();         out.print("<p>page invalid.</p>");     } }  protected void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {     // todo auto-generated method stub       string url = "jdbc:mysql://localhost:3306/";       string dbname = "knowledge";       string driver = "com.mysql.jdbc.driver";       string username = "root";        string password = "";       connection conn = null;               try {         class.forname(driver).newinstance();           conn = (connection) drivermanager.getconnection(url + dbname,username,password);           //st = (statement) conn.createstatement();            string mysqlquery = "insert problems (id,productid,description) values (?,?,?);";           preparedstatement updatestatement = (preparedstatement) conn.preparestatement(mysqlquery);           updatestatement.setint(1,0);           updatestatement.setstring(2, request.getparameter("productid"));           updatestatement.setstring(3, request.getparameter("description"));           int res = updatestatement.executeupdate();                request.setattribute("message", res>0?"record added: " + request.getparameter("description"):"record failed");             conn.close();     } catch (exception e) {         e.printstacktrace();     } {           try {               conn.close();           } catch(exception e) {               e.printstacktrace();           }     }     request.getrequestdispatcher("/problem").include(request, response);   } } 

looks final line trying call same handler same request, causing loop? oracle docs