Types of Randomness

Question

Java storage libraries Randominclude Randomand SecureRandom(and I see ThreadLocalRandom). Are there any others? When will I use each? Sometimes I use it SecureRandomjust to feel better about my primes. It turns out that SecureRandomactually allows you to choose your generator . How and when should I use this?

Finally, Java 8 provides SecureRandom.getInstanceStrong(). I'm not sure what it is, but it is much slower than any previous one. How and when should I use SecureRandom.getInstanceStrong()? Also, is it slow because the noise source is running out?

Answer 1

Randomis predictable, you just need a small sequence of generated numbers, and you can go back and forth through the sequence. See Inverse function of a random Java function for an example of a sequence change.

SecureRandom no.

ThreadLocalRandom- an attempt to correct the fact that Randomit is not thread safe.

Other forms of randomness are possible with various functions - you will have to study the mathematics of random numbers in order to be able to balance between the ones you mentioned and any other algorithm.

SecureRandom getInstanceStrong()(note Strong ) seems to be an even stronger random sequence that is especially resistant to exhibiting long sequences.

Randomness

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private static int lastRandom = 0;

public static int nextRandom() {
  return ++lastRandom;
}

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