How to get value of optional parameters from a url with regex in java

Question

I have some uris which I want to extract parameters if they are exist, I come up with this code. Can someone point me to fix regex to success.

cityId and countryId works as expected but Cant get only numbers after word '-a-'

Regex

// "/city/berlin-a-10284?cityId=123456&countryId=4545"
// "/city/berlin-a-10284"
// "/city/berlin-a-10284?cityId=123456"
// "/city/berlin-a-10284?countryId=4545"



private String ValueExtractor(String url, String searchWord) {

        String regex = "(?<=" + searchWord + ").*?(?=&|$)";
        Pattern pattern = Pattern.compile(regex);
        Matcher matcher = pattern.matcher(url);

        return matcher.find() ? matcher.group() : "";
}


String productId = "";
String cityId = "";
String countryId = "";

if (url.contains("-p-")) {
    productId = ValueExtractor(url, "-a-");
}

if (url.contains("cityId")) {
    cityId = ValueExtractor(url, "cityId=");

}

if (url.contains("countryId")) {
    countryId = ValueExtractor(url, "countryId=");

}

Expected results:

"/city/berlin-a-10284?cityId=123456&countryId=4545" 
productId:10284
cityId: 123456
countryId: 4545

"/city/berlin-a-10284"
productId:10284

"/city/berlin-a-10284?cityId=123456"
productId:10284
cityId: 123456

"/city/berlin-a-10284?countryId=4545"
productId:10284
countryId: 4545

new URI( string ).getPath() would be a better start. docs.oracle.com/en/java/javase/16/docs/api/java.base/java/net/… — markspace
– markspace, Commented Aug 26, 2021 at 20:37

Arvind Kumar Avinash · Accepted Answer · 2021-08-26 20:39:42Z

1

Cant get only numbers after word '-a-'

You can use the regex, (?<=-a-)\d+(?=[?&]|$) to retrieve this number.

(?<=-a-)\d+ specifies one or more digits preceded by -a-.
(?=[?&]|$) specifies positive lookahead for ?, or & or end of line.

answered Aug 26, 2021 at 20:39

Arvind Kumar Avinash

81k10 gold badges98 silver badges144 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

markspace Over a year ago

But regex seems like a poor tool for parsing URIs. Wouldn't using the URI class be better?

Arvind Kumar Avinash Over a year ago

@markspace - URI classes would definitely be better if the full path or parameters are to be extracted. In this particular case, the OP is looking to get a part of the path.

markspace Over a year ago

The OP also has a query string attached to the path in some cases. I really think using URI for parsing the path and the query would be better.

Arvind Kumar Avinash Over a year ago

@markspace - I respect your concern but I am being lazy to post another answer after getting tired of the whole day's work 😊. If you have time, please post an answer.

Collectives™ on Stack Overflow

How to get value of optional parameters from a url with regex in java

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related