return rank(left) - rank(right); // safe because both are nonnegative
  }

  private int rank(T value) {
    Integer rank = rankMap.get(value);
    if (rank == null) {
      throw new IncomparableValueException(value);
    }
    return rank;
  }

  @Override
  public boolean equals(@CheckForNull Object object) {
    if (object instanceof ExplicitOrdering) {

    return rank(left) - rank(right); // safe because both are nonnegative
  }

  private int rank(T value) {
    Integer rank = rankMap.get(value);
    if (rank == null) {
      throw new IncomparableValueException(value);
    }
    return rank;
  }

  @Override
  public boolean equals(@CheckForNull Object object) {
    if (object instanceof ExplicitOrdering) {

      fail();
    } catch (IncomparableValueException expected) {
      assertEquals(0, expected.value);
    }
    reserializeAndAssert(c);
  }

  public void testExplicit_one() {
    Comparator<Integer> c = Ordering.explicit(0);
    assertEquals(0, c.compare(0, 0));
    try {
      c.compare(0, 1);
      fail();
    } catch (IncomparableValueException expected) {
      assertEquals(1, expected.value);

      fail();
    } catch (IncomparableValueException expected) {
      assertEquals(0, expected.value);
    }
    reserializeAndAssert(c);
  }

  public void testExplicit_one() {
    Comparator<Integer> c = Ordering.explicit(0);
    assertEquals(0, c.compare(0, 0));
    try {
      c.compare(0, 1);
      fail();
    } catch (IncomparableValueException expected) {
      assertEquals(1, expected.value);

   * Extending {@link ClassCastException} may seem odd, but it is required.
   */
  @VisibleForTesting
  static class IncomparableValueException extends ClassCastException {
    final Object value;

    IncomparableValueException(Object value) {
      super("Cannot compare value: " + value);
      this.value = value;
    }

    private static final long serialVersionUID = 0;
  }