Java random how does it work

Returns the next pseudorandom Double value between 0. Returns the next uniformly distributed pseudorandom Float value between 0. Returns the next pseudorandom Gaussian double value with mean 0. Returns a uniformly distributed pseudorandom int value generated from this random number generator's sequence.

Returns the next uniformly distributed pseudorandom long value from the random number generator's sequence.

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First Name. Last Name. Phone Number. Start your career transition today with help from a coding bootcamp. Also note: If all scientific papers whose results are in doubt because of bad rand s were to disappear from library shelves, there would be a gap on each shelf about as big as your fist. Improve this answer. Boris Gorelik Boris Gorelik This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post.

Eelke: Is it better now? The problem with randomness is that you can never be sure—but you can pass the generated numbers through a statistical test I remember the chi-square test from my college days and get a percentage called "degree of confidence". Michiel Buddingh Michiel Buddingh 5, 19 19 silver badges 32 32 bronze badges. LCGs do not necessarily produce output in any finite field, never mind evenly spaced numbers. Thank you for the links, I'll drop in another one: en.

But they are quite uncommon nowadays. I have finally found someone who agrees that computers cannot really pick random numbers. I like to think about it like this: computers do not do anything themselves.

In fact, it is arguable they are the stupidest things in the universe. Everything done by computers is programmed by humans. Because we have an intellect, we can pick seemingly random numbers, but that's not true for computers. A millisecond timer is not a fast changing system, for most computational purposes it is a semi-fixed number, changing once in a while. And when it does change, it changes in a completely predictable terms.

In best case the time should be used as a seed, and only once in a while to make sure that the time has changed completely before using it again. So better than a timer is a system that changes really rapidly, and non predictive. Good comment. Tried to mention this disclaimer under "Update". David David Community Bot 1 1 1 silver badge. PRINT " hit any key to roll again with these values hit n for new values and q to quit" PRINT " the number will be added or subtracted first before the multiplier takes effect" reroll: sum!

PRINT "you rolled a :"; sum! John Einem John Einem 41 3 3 bronze badges. Depends on the goal: speed vs quality vs security. Combining several random sources simpliest XOR combines their properties. Sam Ginrich Sam Ginrich 2 2 silver badges 4 4 bronze badges. Sign up or log in Sign up using Google. Sign up using Facebook.