Working of split method for 0.0.0.0. && 0.0.0.0

Question

`

class GfG{
public String multiply(String a,String b){
        String s = "0.0.0.0";
        String[] str = s.split("\\.");
        for(String p:str){
            System.out.println(p);
        }
        return "";
    }
}

` I am splitting "0.0.0.0" and "0.0.0.0.". In both the cases i m getting same array of strings i.e 4 "0" strings. Can someone explain how this split is working for the two above cases.

i added the code for "0.0.0.0" – Akash Panigrahi May 25 '19 at 18:49 — Akash Panigrahi, May 25 '19 at 18:49
Try String[] str = s.split("\\.", -1); and see the magic. – Sambit May 25 '19 at 18:57 — Sambit, May 25 '19 at 18:57

score 2 · Answer 1 · answered May 25 '19 at 18:52

The reason that you are not receiving the empty string that you think should have been returned at the end is by design in split.

From the docs:

public String[] split(String regex)

This method works as if by invoking the two-argument split method with the given expression and a limit argument of zero. Trailing empty strings are therefore not included in the resulting array

The important part of this is that Trailing empty string are therefore not included.

Reference: Official documentation

score 1 · Answer 2 · answered May 25 '19 at 18:50

It appears that you ran the following

jshell> "0.0.0.0".split("\\.")
$1 ==> String[4] { "0", "0", "0", "0" }

jshell> "0.0.0.0.".split("\\.")
$2 ==> String[4] { "0", "0", "0", "0" }

and you are happy with the first result but you are wondering why the last result is not

String[4] { "0", "0", "0", "0", "" }

This is a good question to ask because if the dot was at the beginning of the string you would get the empty string!

jshell> ".0.0.0.0".split("\\.")
$3 ==> String[5] { "", "0", "0", "0", "0" }

This is just how split works. If there is a delimiter at the end of the string, no empty string is returned.

Duplicate of Java String split removed empty values, where it is explained in detail.

Working of split method for 0.0.0.0. && 0.0.0.0

2 Answers2