java - Servlet with Ajax - POST works, but GET does not -

i making application able count numbers written in formulas. in html have put this:

<input type="text" size="20" id="number2" onblur="validate2()"        onfocus = "document.getelementbyid('msg2').innerhtml = ' '"> <br> <div id = "message1">&nbsp</div> 

i have created javascript firstly validating datas , later inserts them 'answer-formula':

function validate2() { var idfield2 = document.getelementbyid("number2"); var data2 = "number2=" + encodeuricomponent(idfield2.value); if (typeof xmlhttprequest != "undefined") {     req = new xmlhttprequest(); } else if (window.activexobject) {     req = new activexobject("microsoft.xmlhttp"); } var url = "validator" req.open("get", url, true);         req.onreadystatechange = inserter2 req.setrequestheader("content-type", "application/x-www-form-urlencoded")  ;     req.send(data2); }  function inserter2() {     if (req.readystate == 4) {         if (req.status == 200) {             var msg1 = req.responsetext             if (msg1 == "") {                 document.getelementbyid("message1").innerhtml = "<div style=\"color:red\">zła nazwa</div>";                 document.getelementbyid("org").value = ''             }             else                 document.getelementbyid("org").value = msg2         }     } } 

and here's code in sending doget:

public void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {     system.out.println("get");      response.setcontenttype("text/html");     writer out = response.getwriter();     string num2 = request.getparameter("number2");     system.out.println(num2);     string org = new string();     if(num2.matches("[\\p{punct}\\d]+")) {         scriptenginemanager mgr = new scriptenginemanager();         scriptengine engine = mgr.getenginebyname("javascript");         try {             org = engine.eval(num2).tostring() + " (" + request.getmethod() + ")";         } catch (exception e) {             e.printstacktrace();         }     }     out.write(org != null ?  org : ""); } 

if change these things post, code work, get, doesn't work @ all. strange situation formula post can read written things in formula, using get, program see formula source null.

if send get, need put formula request. expression:

req.send(data2); 

doesn't make sense when send request, request cannot contain payload except in request string. have add payload url. this:

var url = "validator/?" + data2; req.open("get", url, true);         req.onreadystatechange = inserter2; req.send(); 

hope helps.