android - When i change my api level my http request doesn't work -

when api level set 8, fine. when try set minsdkversion 11, http request xml doesn't work. got exception on if. here code:

url url;     string ciao="";     try {       url = new url("myurl");        urlconnection connection = url.openconnection();         httpurlconnection httpconnection = (httpurlconnection)connection;        int responsecode = httpconnection.getresponsecode();         if (responsecode == httpurlconnection.http_ok) {          inputstream in = httpconnection.getinputstream();          documentbuilderfactory dbf = documentbuilderfactory.newinstance();         documentbuilder db = dbf.newdocumentbuilder();         document dom = db.parse(in);         domsource domsource = new domsource(dom);         stringwriter writer = new stringwriter();         streamresult result = new streamresult(writer);         transformerfactory tf = transformerfactory.newinstance();         transformer transformer = tf.newtransformer();         transformer.transform(domsource, result);         ciao=writer.tostring();       }         }     catch(exception e)     {      }     return ciao; 

ensure manifest has below statement:

<uses-sdk android:minsdkversion="number-of-version-you-want" /> 

then

1. clean project
2. re-build project.
3. right click project , select run updated version of apk generated. use apk.
4. try uninstalling , re-installing app in mobile phone.

note: use asynctask in order avoid anr , networkonmainthreadexception exception on main thread..

edit: please find code asynctask: have used progressdialog in order display "loading please wait" kind of message in case, url call takes longer time.

public class mainactivity extends activity {    @override protected void oncreate(bundle savedinstancestate)  {     .... // code here     // async task can called within onclick code.     new asynctaskoperation().execute(""); }   /* async task called avoid android network on main thread exception. web services need consumed in background.     */ private class asynctaskoperation extends asynctask <string, void, void> {      private progressdialog dialog = new progressdialog(loginactivity.this);      string ciao="";     protected void onpreexecute() {         // display loading spinner         dialog.setmessage("loading... please wait.. ");         dialog.setprogressstyle(progressdialog.style_spinner);         dialog.setinversebackgroundforced(false);         dialog.setcancelable(false);         dialog.setindeterminatedrawable(getresources().getdrawable(r.drawable.progressbar_new));          dialog.show();     }      @override     protected void doinbackground(string... paramsobj) {          try {               url = new url("myurl");                urlconnection connection = url.openconnection();                 httpurlconnection httpconnection = (httpurlconnection)connection;                int responsecode = httpconnection.getresponsecode();                 if (responsecode == httpurlconnection.http_ok) {              inputstream in = httpconnection.getinputstream();              documentbuilderfactory dbf = documentbuilderfactory.newinstance();             documentbuilder db = dbf.newdocumentbuilder();             document dom = db.parse(in);             domsource domsource = new domsource(dom);             stringwriter writer = new stringwriter();             streamresult result = new streamresult(writer);             transformerfactory tf = transformerfactory.newinstance();             transformer transformer = tf.newtransformer();             transformer.transform(domsource, result);             ciao=writer.tostring();               }             }             catch(exception e)             {              }         return null;     }      protected void onpostexecute(void unused)      {         // close progress dialog         dialog.dismiss();         // actions ciao string      } // end of method onpostexecute  } // end of class asynctaskoperation 

}// end of mainactivity