why split function behave like this in java?

Question

if I do

    String a = ""
    String b = a.split(" ")[0];

It is not giving ArrayIndexOutOfBoundException

but when I do

    String a = " "
    String b = a.split(" ")[0];

It is giving me ArrayIndexOutOfBoundException

again when I do

    String a = " abc"
    String b = a.split(" ")[0];

It is not giving me Exception WHY SO?

Answer 1

It's kind of weird.

Thing is, in your first example, the empty String "" is a String, not null. So when you say: Split this "" with the token " ", the patterns doesn't match, and the array you get is the original String. Same as if you did

String a = "abc";
String b = a.split(" ")[0];

The pattern to split doesn't match, so you get one token, the original String.

You get an exception on the second case because the COMPLETE content of your String is exactly the delimiter you've passed to split, so you end up with an empty array.

Let me know if you want some further details, but this is pretty much it.