Regex for splitting at every character but keeping numbers together

Question

I'm looking for a regex that will split a string as follows:

String input = "x^(24-3x)";
String[] signs = input.split("regex here");
for (int i = 0; i < signs.length; i++) { System.out.println(sings[i]); }

with the output resulting in:

"x", "^", "(", "24", "-", "3", "x", ")"

The string is split at every character. However, if there are digits next to each other, they should remain grouped in one string.

Answer 1

You can use this lookaround based regex:

String[] signs = input.split("(?<!^)(?=\\D)|(?<=\\D)");

RegEx Demo

RegEx Breakup

(?<!^)(?=\\D)  # assert if next char is non-digit and we're not at start
|              # regex alternation
(?<=\\D)       # assert if previous character is a non-digit