android - using startsWith and replaceFirst not working for me. -

i print phone contacts in android monitor code below. phone number begins 00 want change 00 + . not working. can tell me wrong please ?

 protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);          contentresolver cr = getcontentresolver();         cursor cur = cr.query(contactscontract.contacts.content_uri,                 null, null, null, null);          if (cur.getcount() > 0) {             while (cur.movetonext()) {                 string id = cur.getstring(                         cur.getcolumnindex(contactscontract.contacts._id));                 string name = cur.getstring(cur.getcolumnindex(                         contactscontract.contacts.display_name));                  if (cur.getint(cur.getcolumnindex(                         contactscontract.contacts.has_phone_number)) > 0) {                     cursor pcur = cr.query(                             contactscontract.commondatakinds.phone.content_uri,                             null,                             contactscontract.commondatakinds.phone.contact_id +" = ?",                             new string[]{id}, null);                     while (pcur.movetonext()) {                         string phoneno = pcur.getstring(pcur.getcolumnindex(                                 contactscontract.commondatakinds.phone.number));                          if (phoneno.startswith("00")) {                             system.out.println(phoneno.replacefirst("00", "+"));                         }                          system.out.println("name: " + name);                         system.out.println("phone no: " + phoneno);                      }                     pcur.close();                 }             }         } 

replacefirst() returns string, doesn't mutate object. should perform assignment:

phoneno = phoneno.replacefirst("00", "+")