String final_key = "service_codeEncrypted_key";
// here is the problem
Replace with the following
String final_key = service_codeEncrypted_key;
and consider this one too
String part_fixed ="";
String part_user ="";
if(parts!=null){
part_fixed = parts[0]; // xxx.xxx.xxx.xxx
part_user = parts[1]; // yyyy
}