Java正则表达式-拆分带前导特殊字符的字符串

Question

I am trying to split a string that contains whitespaces and special characters. The string starts with special characters. When I run the code, the first array element is an empty string.

String s = ",hm  ..To?day,.. is not T,uesday.";
String[] sArr = s.split("[^a-zA-Z]+\\s*");

Expected result is ["hm", "To", "day", "is", "not", "T", "uesday"]

Can someone explain how this is happening?

Actual result is ["", "hm", "To", "day", "is", "not", "T", "uesday"]

Answer 1

Split is behaving as expected by splitting off a zero-length string at the start before the first comma.

To fix, first remove all splitting chars from the start:

String[] sArr = s.replaceAll("^([^a-zA-Z]*\\s*)*", "").split("[^a-zA-Z]+\\s*");

Note that I've altered the removal regex to trim any sequence of spaces and non-letters from the front.

You don't need to remove from the tail because split discards empty trailing elements from the result.

Answer 2

我将其简化为两步过程，而不是尝试实现纯正则表达式split()操作：

s.replaceAll( '[^a-zA-Z]+', ' ' ).trim().split( ' ' )