Empty是任何字符串的子集。

Empty is a subset of any string.

将它们视为每两个字符之间的差异。

Think of them as what is between every two characters.

存在无限数字的方式在任何大小的线上的点......

Kind of the way there are an infinite number of points on any sized line...

（嗯......我想知道如果我使用微积分来连接无数个空字符串我会得到什么）

(Hmm... I wonder what I would get if I used calculus to concatenate an infinite number of empty strings)

请注意.equals（）仅限。

Note that "".equals("") only though.