A random number generator in Java

RandomNumberGenerator.java

import java.util.Random;

class RandomNumberGenerator {
  public static String usage = "Usage: java RandomNumberGenerator <lines> [seed]";

  public static void main(String[] args) {
    if (args.length > 2) {
      System.err.println("Too many arguments!");
      System.err.println(usage);
      System.exit(1);
    } else if (args.length == 0) {
      System.err.println("Requires at least one argument");
      System.err.println(usage);
      System.exit(1);
    }

    int count = parseCriticalInt(args[0]);

    Random rng = null;
    if (args.length == 2) {
      int seed = parseCriticalInt(args[1]);
      rng = new Random(seed);
    } else {
      rng = new Random();
    }

    for (int i = 0; i < count; ++i) {
      System.out.println(rng.nextInt(9));
    }
  }

  public static int parseCriticalInt(String stringValue) {
    int intValue = 0;
    try {
      intValue = Integer.parseInt(stringValue);
    } catch (NumberFormatException e) {
      System.err.println(stringValue + " must be an integer");
      System.exit(2);
    }
    return intValue;
  }
};