CODEWITHSUNDEEP
javasecurityrandom
anoopelias
anoopelias

Reputation: 9548

Generate secure random number uniformly over a range in Java

How do I generate a secure uniform random number within a range? The range could be between 0 to 100. (The upper bound is not a power of 2).

java.security.SecureRandom seems to provide the range 0..2^n.

Upvotes: 14

Views: 31926

Answers (2)

Peter Lawrey
Peter Lawrey

Reputation: 533530

You can do

Random rand = new SecureRandom()
// 0 to 100 inclusive.
int number = rand.nextInt(101);

or

// 0 inclusive to 100 exclusive.
int number = rand.nextInt(100);

Note: this is more efficient than say (int) (rand.nexDouble() * 100) as nextDouble() needs to create at least 53-bits of randomness whereas nextInt(100) creates less than 7 bits.

Upvotes: 20

Snehal Patel
Snehal Patel

Reputation: 1330

Try below code snap

    SecureRandom random = new SecureRandom();

    int max=50;
    int min =1;

    System.out.println(random.nextInt(max-min+1)+min);

Upvotes: 10

Related Questions