Regex for parsing queryString

Question

Hi am looking for an Regular Expression which parses QueryString.Am using the below regex:

Pattern pr1=Pattern.compile("[\\?&](?<name>[^&=]+)=(?<value>[^&=]+)");

But its throwing

java.util.regex.PatternSyntaxException: Look-behind group does not have an obvious maximum length near index 18
[\?&](?<name>[^&=]+)=(?<value>[^&=]+)
                  ^

Can anyone help me on

Are you sure that you're using Java 7 / JDK 1.7? Because it looks like the regex-engine isn't recognizing the named capture-group notation. — ruakh
– ruakh, Commented Feb 14, 2012 at 16:15
doing this without a regex is (I think) a lot more clear and straightforward. — Kevin
– Kevin, Commented Feb 14, 2012 at 16:26

anubhava · Accepted Answer · 2012-02-14 16:52:58Z

6

Java <1.7 doesn't support named groups so change your regex to:

Pattern pr1 = Pattern.compile("[\\?&]([^&=]+)=([^&=]+)");

and then from the Matcher, get group # 1 and # 2 for the name and value.

Update:

String str =
        "http://test.abc.com/test/http/com/google/www/:/?code=1234&Id=123354455656%22";
Pattern pt = Pattern.compile("[\\?&]([^&=]+)=([^&=]+)");
Matcher m = pt.matcher(str);
if (m.find())
    System.out.printf("name=[%s], value=[%s]%n", m.group(1), m.group(2));

OUTPUT:

name=[code], value=[1234]

edited Feb 14, 2012 at 16:52

answered Feb 14, 2012 at 16:20

anubhava

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2 Comments

rkhm Over a year ago

StringBuffer str1=new StringBuffer("test.abc.com/test/http/com/google/www/:/…);

rkhm Over a year ago

My url goes like the above one.can u help me.am getting an error as match not found

Diego · Accepted Answer · 2012-02-14 16:16:18Z

0

I don't know what you are trying to accomplish with "%5b^&=%5d+">. Sounds like it's complaining about the >. This can help: http://stevenbenner.com/2010/03/javascript-regex-trick-parse-a-query-string-into-an-object/

answered Feb 14, 2012 at 16:16

Diego

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Comments

Radu Simionescu · Accepted Answer · 2015-11-30 00:33:52Z

0

Lookbehind expressions must look for a fixed length string. You cannot use regex features such as * ? + inside lookbehind assertions. (?<name>[^&=]+) is a lookbehind denoted by '?<' and it contains a '+'. Maybe you wanted to comment out the '<'?

answered Nov 30, 2015 at 0:33

Radu Simionescu

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