mixster

public class primes
{

    public static void main(String[] args)
    {
    final long startTime = System.nanoTime();

        boolean[] composite = new boolean[50000001];

    int limit = /*sqrt(50000000)*/ 7071;

        for(int i = 3; i <= limit; i += 2)
            if(!composite[i])

            {

              for(int j = i * 2 + i; j <= 50000000; j += i * 2)
          composite[j] = true;

            }

    final long endTime = System.nanoTime();

    for(int i = 3; i <= 50/*000000*/; i += 2)
      if (!composite[i])
        System.out.println(i);

    System.out.print(endTime - startTime);
    System.out.println(" ns");
    }

}