title: Runtime error. Trying to generate random ints
body: <p>I am trying to run this program but am getting a strange runtime error message (a runtime error) where the I get a pop up window with a yellow exclamation point and a the Java coffee cup.  The message reads "The Java class file Account.class could not be launched.  Check console for possible error messages."  I have checked the console but don't see any errors.  Can anyone see whats wrong with this program? Thanks so much for all the help.  I am using BlueJ on a Mac to write, compile, and run this program.  </p>
  
  <pre><code>import java.util.Random;
  public class ArrayDemo
  {
  public static void main ( String[] args )
  {
      System.out.println("Begin Program");
      int arr[] = new int[100];
      Random randomGenerator = new Random();
  }
  
  public static int[] calculateEven ( int[]a )
  {
      int arr[] = new int[100];
      int idx = 0;
  
      for ( int j = 0; j &lt; a.length; j++)
      {
          if (a[j]%2==0)
          {
              arr[idx] = a[j];
              idx++;
          }
      }
      return arr;
  }
  
  public static int[] calculateOdd ( int[]b )
  {
      int arr[] = new int [100];
      int idx = 0;
  
      for ( int i = 0; i &lt; b. length; i++)
      {
          if (b[i]%2!=0)
          {
              arr[idx] = b[i];
              idx++;   
          }   
      }
      return arr;
   }   
  }
  </code></pre>