Java implementation of Sieve of Eratosthenes

Sieve.java

import java.util.List;

public class Sieve {
  static List<Integer> sieve(int n) {
    List<Integer> l = new java.util.ArrayList<Integer>();
    byte[] bs = new byte[(n / 8) + 1];  // 0 => maybe prime
    bs[0] = (byte) 0xc0;  // skip 0 and 1
    for (int i = 2; i <= n / 2; i++) {
      for (int c = i; c <= n; c += i) {
        int bidx = c / 8;
        int bit = c % 8;  // 2 -> 2, 7 -> 7, 8 -> 0, 9 -> 1
        byte mask = (byte) (1 << (7 - bit));
        if (c == i) {
          if ((bs[bidx] & mask) != 0) {
            break;
          }
          continue;
        }
        bs[bidx] |= mask;
      }
    }
    int m = 0;
    for (byte b : bs) {
      for (int i = 7; i >= 0; i--) {
        if ((b & (1 << i)) == 0) {
          int prime = m + (7 - i);
          if (prime > n) {
            return l;
          }
          l.add(prime);
        }
      }
      m += 8;
    }
    return l;
  }
  
  public static void main(String args[]) {
    for (int i : sieve(Integer.parseInt(args[0]))) {
      System.out.println(i);
    }
  }
}