unique random number generation

Question

I'm looking for way to generate unique random numbers based on current time using java. I'm a c++ programmer and in c++ I usually seed the Random with time so at each specific moment I can get a unique random number and it works like this :

sRand((time)Null);
x=Rand();

In java I found that I can use the same method by seeding the random number with time like this:

Random rand = new Random(System.currentTimeMillis());

Here is the problem I have used all the methods I found over the internet for generating a random number in java but none of them were truly random and they ranged from negative to positive numbers. For example:

Random rand = new Random(System.currentTimeMillis());
int x=rand.nextInt(); // or long or float ...

What I get is a series of not truly random numbers and the result is really different than in C++.

I just want to know what the best way to do this in java is, some like or very close to TAC number generation.

Answer 1

Java's and C++ random numbers are both pseudorandom. Of course the algorithms are different, so the results are different too.

If you would like a random number generator that is strong enough to use for cryptography, you can use SecureRandom: its interface is less intuitive, and it consumes more CPU, but the quality of its output is much higher than of a regular PRNG of Java,