Prime Number Generator Logic

Question

I am supposed to make a class PrimeNumberGenerator which has a method nextPrime that will print out all prime numbers up to a number the user input

Answer 1

Check this algorithm based on the sieve of Eratosthenes for prime numbers. Of course you need to adapt it to your program.

boolean isPrime[] = new boolean [N+1];
for (int i=2; i <=N; i++)
    isPrime[i] = true;

//mark non-primes <=N using Sieve of Eratosthenes
for (int i=2; i*i<=N; i++) 
{
    //if is a prime,then mark multiples of i as non prime 
    for (int j=i; i*j<=N; j++) 
    {
        isPrime[i*j] = false;
    }
}

for (int i=2; i<=N; i++) 
    if (isPrime[i])
        //Do something.......