Why do you get the different sized arrays from invoking split() on an empty string and a string which consists of only separators

Question

After you split an empty string, you get an array of 1 element After you split a string that have only separators/delimiters(for example, only special characters which the split(\W) will remove), you get an array of 0 elements?

They both lead to empty tokens so surely they have the same length arrays? But why not?

Related: https://stackoverflow.com/questions/14414582/java-split-string-to-array — Mark Rotteveel, Sep 04 '17 at 07:33

Slava Vedenin · Accepted Answer · 2017-09-04T07:29:17.150

3

Because, split have two case:

If no match was found, return new String[] { this }, for example:

"1111".split(",") // {"1111"}
" ".split(",") // {" "}
"".split(",") // {""}

It match was found, return new String[resultSegmentCount], when resultSegmentCount = 0, for example:

 " , ".split(",") // {" ", " "}
 " ,".split(",") // {" "}
 ", ".split(",") // {" "}
 ",".split(",") // {}

edited Sep 04 '17 at 07:29

answered Sep 03 '17 at 19:39

Slava Vedenin

58,326
13
40
59

You can see the current source code of the `String.split(String, int)` method [at grepcode](http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/8u40-b25/java/lang/String.java#String.split%28java.lang.String%2Cint%29). Note that `String.split(String)` simply calls `String.split(String, int)` with an integer argument of zero. – Bobulous Sep 03 '17 at 19:42

Why do you get the different sized arrays from invoking split() on an empty string and a string which consists of only separators

1 Answers1