A Java program that will find all prime numbers between 0 and N.

sieve.java

import java.util.ArrayList;

/**
 * This program finds all of the prime numbers between 0 and a number supplied by the user,
 * inclusive.
 * 
 * @author BJ Peter DeLaCruz
 * @version 1.1
 */
public class CountingPrimeNumbers {

  public static ArrayList<Integer> arrayList1;
  public static ArrayList<Boolean> arrayList2;

  public static void main(String[] args) {

    // Check if only one argument is supplied,
    // which is the upper bound for finding prime numbers.
    if (args.length != 1) {
      System.exit(1);
    }

    int num = Integer.parseInt(args[0]);

    long startTime, endTime, aveTime = 0;

    for (int j = 0; j < 10; j++) {

      arrayList1 = new ArrayList<Integer>();
      arrayList2 = new ArrayList<Boolean>();

      // Populate the array list from 0 to upper bound.
      for (int i = 0; i <= num; i++) {
        arrayList1.add(new Integer(i));
        arrayList2.add(new Boolean(true));
      }

      // Find all of the prime numbers between 0 and upper
      // bound.
      startTime = System.currentTimeMillis();
      for (int i = 2; i <= num; i++) {
        if (isBiggestPrime(arrayList1.get(i))) {
          break;
        }
      }
      endTime = System.currentTimeMillis();
      aveTime += (endTime - startTime);

      // Display the time it took to find all of the prime
      // numbers from 0 to upper bound.
      String runtime = (endTime - startTime) + " ms";
      System.out.println("Run #" + j + ": " + runtime);

    }

    System.out.println("Average time: " + aveTime / 10 + " ms");

    /*
     * // Print all of the prime numbers from 0 to upper bound. for (int i = 2; i <= num; i++) { if
     * (arrayList2.get(i)) { System.out.println(arrayList1.get(i)); } }
     */

  }

  private static boolean isBiggestPrime(int i) {
    // If i*i is greater than the last element in the
    // array list, stop finding prime numbers (all of
    // the prime numbers have already been found).
    if ((i * i) >= arrayList1.get(arrayList1.size() - 1)) {
      return true;
    }
    getPrimeNumbers(i);
    return false;
  }

  private static void getPrimeNumbers(int i) {
    for (int j = i; j < arrayList1.size(); j++) {
      // If the current element j being tested is
      // divisible by i, then j is not a prime number.
      if (j % i == 0 && j != i) {
        arrayList2.set(j, false);
      }
    }
  }

}