Print the input, see what's wrong with your code.

so clever dude...

also: don't forget to always use the spoiler tag when discussing code. (I have added the tag for you)

as i said im a beginner i dont understand that stack trace, i searched on google too about this program and the line which i have wrote are musch same. but still im not getting where is the problem
if also added this line at the begining
if(array.lengh < 1 || array == null) return array; // but still error.
and is there any way by which i get notification without tapping evertime on notification icon.
and thank u, for replying back :)

sort of, yes. Because in that case, the fact that you didn't find it yet just means one thing: you didn't actually take the time to read the different bits of information already available to you.

Keep in mind that on codewars, you can print the inputs or whatever you want to the console, from within your function (console.log, in JS edit: System.out.println rather, since you seem to be doing Java). That might help too.

cheers

in short ur telling me to find the error by myself, is it

:(

Hi,

1. spoiler flag, please, when you post code
2. you'll quickly discover that 99,99% of the time, on published kata with thousands of solutions already, when someone "thinks that my code is correct but..." that someone did something wrong somewhere. And you did...
3. read the info you have, for your problem: the name of the failed tests is a strong indication already. And you surely got an error message or maybe a traceback about an error -> read it. If you wanna learn programming, you have to be able to extract usefull information on your own, from this kind of stuff.

Everything you need is already available to you to solve your problem. Just dig into it.

cheers