I wish I could vote on Best Practices and Clever at the same time :)

Character.compare('1','2'); //out: -1
This output means that that "2:..." will go before "1:..." as required in the solution;

so clever done,i was stuck by this kata

Love it

Guys, correct me if im wrong but this solution proposes to use regex-based replaceAll() in a loop, which compiles and applies regex for every single char, which is, well, slow.

Something like this:
int[] a = {3, 2147483646};
int[] b = {9, 4};
returns true...