Sieve of Eratosthenes

sieve.java

// Sieve of Eratosthenes

public int sieve_of_eratosthenes(int input)
{
    boolean [] is_prime = new boolean [input];
    int number_of_primes = 0;
    
    // Set all values to true
    Arrays.fill(is_prime, Boolean.TRUE)
    
    
    // Sift
    for (int i = 2; i <= sqrt(input); i++)
    {
        if (is_prime[i])
        {
            for (int j = pow(i, 2); j < input; j++)
            {
                if ((j % i) == 0)
                {
                    is_prime[j] = false;
                }
            }
        }
    }
    
    // Collect number of primes
    for (int i = 2; i < input; i++)
    {
        if (is_prime[i])
        {
            number_of_primes++;
            System.out.println("%d %n", is_prime[i]);
        }
    }
    
    return number_of_primes;
}