Java RegEx find, except when between quotes

Question

I need a Java RegEx to split, or find something in a string, but exclude stuff that's between double quotes. What I do now is this:

String withoutQuotes = str.replaceAll("\\\".*?\\\"", "placeholder");
withoutQuotes = withoutQuotes.replaceAll(" ","");

but this doesn't work nice with indexOf, and I also need to be able to split, for example:

String str = "hello;world;how;\"are;you?\""
String[] strArray = str.split(/*some regex*/);
// strArray now contains: ["hello", "world", "how", "\"are you?\"]

quotes are always balanced
quotes can be escaped with \"

Any help is appreciated

Are quotes always balanced? And can these quotes be escaped using `\"` — anubhava, Nov 04 '13 at 15:46
oh sorry, forgot to mention. Yes, quotes are balanced, and yes, they can be escaped with \" — Dirk, Nov 04 '13 at 15:50
What do you mean the first thing doesn't work nice with indexOf? — cangrejo, Nov 04 '13 at 16:10
if you save the index, and then use it on the original string, it won't be the same char, because the placeholder will probably have a different length from the original quoted text — Dirk, Nov 04 '13 at 16:31

anubhava · Accepted Answer · 2013-11-04T17:15:58.620

5

Ok here is a code that will work for you:

String str = "a \"hello world;\";b \"hi there!\"";
String[] arr = str.split(";(?=(([^\"]*\"){2})*[^\"]*$)");
System.out.println(Arrays.toString(arr));

This regex find a semi-colon if it is followed by even number of double quotes (which means ; is outside quotes).

OUTPUT:

[a "hello world;", b "hi there!"]

PS: It doesn't take care of escaped quotes like \"

edited Nov 04 '13 at 17:15

answered Nov 04 '13 at 16:52

anubhava

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It works almost perfectly, but when I try this: `a "hello world;"; b "hi there!";`, it returns `["a "hello world"",""","b "hi there""]` – Dirk Nov 04 '13 at 17:09
Can you give me a valid Java String value that I can try. – anubhava Nov 04 '13 at 17:10
Here you go: `a \"hello world;\";b \"hi there!\"` – Dirk Nov 04 '13 at 17:11
see updated answer though `It doesn't take care of escaped quotes like \"` – anubhava Nov 04 '13 at 17:16
is there an easy way to add that? otherwhise I'll think of some other way to accomplish that – Dirk Nov 04 '13 at 17:18
That's what I tried but it broke this simple case as well. I believe doing all that via regex will immensely difficult. – anubhava Nov 04 '13 at 17:20
OK, then I'll think up something else. Thank you for your time again – Dirk Nov 04 '13 at 17:20

score 0 · Answer 2 · edited May 23 '17 at 12:11

Resurrecting this question because it had a simple regex solution that wasn't mentioned. (Found your question while doing some research for a regex bounty quest.)

\"[^\"]*\"|(;)

The left side of the alternation matches complete quoted strings. We will ignore these matches. The right side matches and captures semi-colons to Group 1, and we know they are the right semi-colons because they were not matched by the expression on the left.

Here is working code (see online demo):

import java.util.*;
import java.io.*;
import java.util.regex.*;
import java.util.List;

class Program {
public static void main (String[] args) throws java.lang.Exception  {

String subject = "hello;world;how;\"are;you?\"";
Pattern regex = Pattern.compile("\"[^\"]*\"|(;)");
Matcher m = regex.matcher(subject);
StringBuffer b= new StringBuffer();
while (m.find()) {
    if(m.group(1) != null) m.appendReplacement(b, "SplitHere");
    else m.appendReplacement(b, m.group(0));
}
m.appendTail(b);
String replaced = b.toString();
String[] splits = replaced.split("SplitHere");
for (String split : splits) System.out.println(split);
} // end main
} // end Program

Reference

Java RegEx find, except when between quotes

2 Answers2