Question

I can’t get these examples from the SUN tutorial of String split:

E.g. for "boo:and:foo"

Regex   Limit   Result  

o   5   { "b", "", ":and:f", "", "" }  
o   -2  { "b", "", ":and:f", "", "" }  
o   0   { "b", "", ":and:f" }  

I can’t understand the result.
I read that for negative limit the pattern is applied as many times as possible and for positive limit it is applied n-1 times etc.

But I can’t understand how the resulting array is formed in each case.

E.g. in first case why we have 1 “” in location 1 but 2 “” in locations 3 and 4?
Same for the rest.

Any help?

Answer 1

Let’s start by understanding all possible splits. I think "b" and ":and:f" are clear.

The empty strings came from splitting between o‘s (fo-""-o,bo-""-o), and splitting after the last o – until the end of the string, which is again – an empty strng.

So totally we have 5 matching strings that the split can return.

If we split using 5 – we return at most 5 substrings, whcih is exactly the 5 substrings we have, resulting in the first output:

If the limit n is greater than zero then the pattern will be applied
at most n – 1 times, the array’s length will be no greater than n, and
the array’s last entry will contain all input beyond the last matched
delimiter

If we split using -2, we return as much as possible [which is identical to 5 in this case]:

If n is non-positive then the pattern will be applied as many times as
possible and the array can have any length

If we split using 0, we return as much as possible – but we discard al the trailing empty strings:

If n is zero then the pattern will be applied as many times as
possible, the array can have any length, and trailing empty strings
will be discarded

Note: If you want to ignore the empty strings between occurances of o, you should split with the regex "o+" – which takes as much o‘s as possible, thus resulting in no empty strings from between o‘s