提供正则表达式时，Java中的String.split（）方法到底如何工作？

提供正则表达式时，Java中的String.split（）方法到底如何工作？

它

"\S"

在正则表达式引擎中表示

S

非空白字符的每个字符上进行拆分。

因此，让我们尝试分割

"xx"

非空白（

S

）。由于此正则表达式可以用一个字符进行匹配，因此可以对其进行迭代以标记拆分的位置（我们将使用竖线

|

进行表示）。

• 是

  'x'

  一个非空白？是的，让我们标记一下

  | x

• 是

  ' '

  一个非空白？不，所以我们保持原样
• 是最后一个

  'x'

  非空白吗？是的，让我们标记一下

  | |

因此，作为结果，我们需要在开始和结束时拆分字符串，这最初会给我们结果数组

["", " ", ""]   ^    ^ - here we split

但是由于删除了结尾的 空字符串 ，结果将是

[""," "]     <- result        ,""] <- removed trailing empty string

因此split返回

["", " "]

仅包含两个元素的数组。

顺便说一句。要关闭删除最后一个空字符串的 *** 作，您需要使用

split(regex,limit)

limit的负值，例如

split("\S",-1)

。

---

现在回到您的示例。如果您有数据，则将每个

I am preparing for OCPJP| || ||||||||| ||| |||||

意思是

 ""|" "|""|" "|""|""|""|""|""|""|""|""|" "|""|""|" "|""|""|""|""|""

所以这代表这个数组

[""," ",""," ","","","","","","","",""," ","",""," ","","","","",""]

但是由于

""

删除了结尾的空字符串（如果它们的存在是由split引起的-
有关更多信息，请访问：混淆String.split的输出）

[""," ",""," ","","","","","","","",""," ","",""," ","","","","",""]^^ ^^ ^^ ^^ ^^

您得到的结果数组仅包含以下部分：

[""," ",""," ","","","","","","","",""," ","",""," "]

正好是16个元素