Regex causing Pattern Syntax Exception

Question

I am trying to create a #replaceAll regex to file out certain characters.

I tried the following

msg.replaceAll("[^\\w~!@#$%^&*()-=_+`[]{}\\|:;'\"<>,./\\]", "");

but it gave me this error

INFO Caused by: java.util.regex.PatternSyntaxException: Unclosed character class near index 36
07.09 00:07:24 [Server] INFO [^\w~!@#$%^&*()-=_+`[]{}\|:;'"<>,./\]
07.09 00:07:24 [Server] INFO ^

I've tried searching online but don't know exactly what I'm doing wrong.

You need to escape -, [ and ] inside your character class — Nick
– Nick, Commented Sep 7, 2019 at 4:38

flyingfox · Accepted Answer · 2019-09-07 04:45:20Z

1

For your regex expression,you have add \\ before the last ] and do not escape for the first [,and also you need to escape -,after changing it to

[^\w~!@#$%^&*()\-=_+`\[\]{}\|:;'\"<>,./]

it works fine in my side

msg = msg.replaceAll("[^\\w~!@#$%^&*()\\-=_+`\\[\\]{}\\|:;'\\\"<>,./]", "");

answered Sep 7, 2019 at 4:45

flyingfox

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5 Comments

Dan Over a year ago

This worked but for some reason it's not replacing '\'

flyingfox Over a year ago

@Dan for '\' you need to escape itself

Dan Over a year ago

Isn't that way '\\\' does?

flyingfox Over a year ago

@Dan you need to use '\\\\' four backslash instead

user85421 Over a year ago

BTW it is not the "before the last ]" - the last one should not be escaped since closing the [] pattern (example/code is correct (in that regard))

Emma Marcier · Accepted Answer · 2019-09-07 04:59:46Z

1

My guess is that maybe this expression might be desired or close to one:

import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class re{

    public static void main(String[] args){


        final String regex = "[^\\w~!@#$%^&*()=_+`\\[\\]{}|:;'\"<>,.\\\/-]";
        final String string = "ábécédééefg";
        final String subst = "";

        final Pattern pattern = Pattern.compile(regex);
        final Matcher matcher = pattern.matcher(string);

        final String result = matcher.replaceAll(subst);

        System.out.println(result);

    }
}

Output

bcdefg

If you wish to explore/simplify/modify the expression, it's been explained on the top right panel of regex101.com. If you'd like, you can also watch in this link, how it would match against some sample inputs.

edited Sep 7, 2019 at 4:59

answered Sep 7, 2019 at 4:47

Emma Marcier

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1 Comment

user85421 Over a year ago

just a little note: regex101 does not have the Java flavor, there might be some minor differences

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