java.lang.StackOverflowError while using a RegEx to Parse big strings

Question

This is my Regex

((?:(?:'[^']*')|[^;])*)[;]

It tokenizes a string on semicolons. For example,

Hello world; I am having a problem; using regex;

Result is three strings

Hello world
I am having a problem
using regex

But when I use a large input string I get this error

Exception in thread "main" java.lang.StackOverflowError
at java.util.regex.Pattern$GroupHead.match(Pattern.java:4168)
at java.util.regex.Pattern$Loop.match(Pattern.java:4295)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4227)
at java.util.regex.Pattern$BranchConn.match(Pattern.java:4078)
at java.util.regex.Pattern$CharProperty.match(Pattern.java:3345)
at java.util.regex.Pattern$Branch.match(Pattern.java:4114)
at java.util.regex.Pattern$GroupHead.match(Pattern.java:4168)
at java.util.regex.Pattern$Loop.match(Pattern.java:4295)
at java.util.regex.Pattern$GroupTail.match(Pattern.java:4227)

How is this caused and how can I solve it?

Answer 1

Unfortunately, Java's builtin regex support has problems with regexes containing repetitive alternative paths (that is, (A|B)*). This is compiled into a recursive call, which results in a StackOverflow error when used on a very large string.

A possible solution is to rewrite your regex to not use a repititive alternative, but if your goal is to tokenize a string on semicolons, you don't need a complex regex at all really, just use String.split() with a simple ";" as the argument.