Help on testing algorithm time

Question

Hello everybody:
I want to ask a question about testing algorithm time.
In my program, I always got the encryption time is zero. And some times is 15ms or 16ms. I test the time like this (ignore the unnecessary part):
long startTime = TimeCounter.startTime();
//generate a key by according algorithm
SecretKey key = KeyGenerator.getInstance(algorithm).generateKey();
Encryption encrypter = new Encryption(key);
encrypter.encrypt(si);
SecretInformation decrypted = encrypter.decrypt();
System.out.println(TimeCounter.period(startTime));
System.out.println(key);
System.out.println(startTime);
System.out.println(System.currentTimeMillis());
Could you point out the problem? Thank you very much.

Answer 1

But If I test in a loop ,,the result is not the
algorithm time?Why not! If you repeat the same operation 10,000 times and time the total then it is a simple matter to work out how long (on average) a single operation took!