35. 使用实例属性替代序数

    1. public enum Ensemble {
    2.     SOLO(1), DUET(2), TRIO(3), QUARTET(4), QUINTET(5),
    3.     NONET(9), DECTET(10), TRIPLE_QUARTET(12);
    6.     Ensemble(int size) { this.numberOfMusicians = size; }
    7. }