Example 4 (4)
Possible application code:
Date today = …;Date easter = new Date(2001, 4, 15);today.advance(16);if (today.compareTo(easter) < 0) System.out.println(today.toString());
Impossible application code:
today.d += 16;System.out.println(today.y + '-' + today.m + '-' + today.d);