public String generateRandomId(){
String chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIGKLMNOPQRSTUVWXYZ";
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < 16; i++) {
buffer.append(chars.charAt(new Random().nextInt(chars.length())));
}
buffer.insert(0, "TR");
return buffer.toString();
}