tij 中的代码，仔细研究一下
运行结果：
---------- java ----------
Bowl(1)
Bowl(2)
Table()
f(1)
Bowl(4)
Bowl(5)
Bowl(3)
Cupboard()
f(2)
Creating new Cupboard() in main
Bowl(3)
Cupboard()
f(2)
Creating new Cupboard() in main
Bowl(3)
Cupboard()
f(2)
f2(1)
f3(1)
Trackback: http://tb.donews.net/TrackBack.aspx?PostId=224229