string.split（“（？！^）”）说明

Question

I'm trying to split the characters of the String to a String array. I found the solution here .

The solution is perfect, however I don't get how .split("(?!^)") worked. I'm familiar with the basics of split() method. Can someone provide an explanation?

Answer 1

(?!^) is a regular expression consisting of a negative lookahead . ^ is an anchor used to signify the start of the string. (?!^) matches all 0-length strings that are not followed by ^ , the start of the string. In other words, it matches all 0-length strings except that at the start of the string.

For example, in the string abc , there will be 3 matches: one between a and b , one between b and c , and one after the c . Splitting on these matches produces the desired array (note that the 1-argument version of split() discards any trailing empty strings, which is why none are included in the resulting array).