import java.util.Comparator;
import static java.text.MessageFormat.format;

/**
 * Created by IntelliJ IDEA.
 * User: niazis
 * Date: Jan 29, 2007
 * Time: 3:31:17 PM
 */
public class Test
{
  public static void main(String[] args)
  {

    Object o = new Object();

    testComparatorx(new NullnessComparator<Object>(),o);
    testComparatorx(new NullnessComparatorSplit<Object>(),o);
    testComparatorx(new NullnessComparatorCorrectSplit<Object>(), o);
    testComparatorx(new NullnessComparatorAlt<Object>(),o);
    testComparatorx(new NullnessComparatorAltSplit<Object>(),o);


  }

  private static <X> void testComparatorx(Comparator<X> comparator, X o)
  {
    System.out.println(format("{0}\t{1}\t{2}\t{3}\t[{4}]",
                              comparator.compare(null, o),
                              comparator.compare(null, null),
                              comparator.compare(o, o),
                              comparator.compare(o, null),
                              comparator.getClass().getSimpleName()
    )
    );
  }

  private static class NullnessComparator<T> implements Comparator<T>
  {
    public int compare(Object x, Object y)
    {
      if (x == null && y != null)
        return -1;
      else if (x != null && y == null)
        return 1;
      return 0;
    }
  }
  private static class NullnessComparatorSplit<T> implements Comparator<T>
  {
    public int compare(Object x, Object y)
    {
      if (x == null)
        if (y != null)
          return -1;
        else if (x != null && y == null)
          return 1;
      else if (x != null && y == null)
        return 1;
      return 0;
    }
  }
  private static class NullnessComparatorCorrectSplit<T> implements Comparator<T>
  {
    public int compare(Object x, Object y)
    {
      if (x == null)
      {
        if (y != null)
          return -1;
        else if (x != null && y == null)
          return 1;
      }
      else if (x != null && y == null)
        return 1;
      return 0;
    }
  }
  private static class NullnessComparatorAlt<T> implements Comparator<T>
  {
    public int compare(Object x, Object y)
    {
      if (x == null && y != null)
        return -1;
      else if (x != null && y == null)
        return 1;
      else
        return 0;
    }
  }

  private static class NullnessComparatorAltSplit<T> implements Comparator<T>
  {
    public int compare(Object x, Object y)
    {
      if (x == null)
        if (y != null)
          return -1;
        else if (x != null && y == null)
          return 1;
        else
          return 0;
      else if (x != null && y == null)
        return 1;
      else
        return 0;
    }
  }
}