// Function To Generate AlphaNumeric Random Strings that will be used as unique Invoice ID.
public String invoiceIDGenerator() {
long decimalNumber = System.nanoTime();
String strBaseDigits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
String invoiceID = "";
int mod = 0;
while (decimalNumber != 0) {
mod = (int) (decimalNumber % 36);
invoiceID = strBaseDigits.substring(mod, mod + 1) + invoiceID;
decimalNumber = decimalNumber / 36;
}
return invoiceID;
}
