CODEWITHSUNDEEP
javarandombiginteger
rainman
rainman

Reputation: 2649

Generate random number of n digits or more

I saw many examples to generate random numbers in a specific range [min-max], but i need java code that generates random numbers of n digits or more, so in this case min= 10000000 and no max.

Note - I am using BigInteger

Upvotes: 0

Views: 864

Answers (2)

Peter Walser
Peter Walser

Reputation: 15706

You can use the constructor BigInteger(int numBits, Random rnd) to generate positive random numbers with N bits.

As you want to have a minimum, you can add that as an offset to the generated numbers:

Random random = ThreadLocalRandom.current();
BigInteger base = BigInteger.valueOf(10000000); // min
int randomBits = 50; // set as many bits as you fancy

BigInteger rnd = base.add(new BigInteger(randomBits, random));

Upvotes: 3

rossum
rossum

Reputation: 15685

BigInteger accepts a decimal String in one of its constructors. Generate individual digits and append them to a String. When you have enough digits in your String, create your BigInteger from the String. You may want to constrain the first digit to be in [1 .. 9] to avoid leading zeros, depending on your exact requirement.

Upvotes: 1

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