1 private int hash; // Default to 0
 2 public int hashCode() {
 3         int h = hash;
 4         if (h == 0 && value.length > 0) {
 5             char val[] = value;
 6             for (int i = 0; i < value.length; i++) {
 7                 h = 31 * h + val[i];
 8             }
 9             hash = h;
10         }
11         return h;
12 }