How to extract parameters from a given url

Question

In Java I have:

String params = \"depCity=PAR&roomType=D&depCity=NYC\";

I want to get values of depCity parameters (PA

Answer 1

Not sure how you used find and group, but this works fine:

String params = "depCity=PAR&roomType=D&depCity=NYC";

try {
    Pattern p = Pattern.compile("depCity=([^&]+)");
    Matcher m = p.matcher(params);
    while (m.find()) {
        System.out.println(m.group());
    } 
} catch (PatternSyntaxException ex) {
    // error handling
}

However, If you only want the values, not the key depCity= then you can either use m.group(1) or use a regex with lookarounds:

Pattern p = Pattern.compile("(?<=depCity=).*?(?=&|$)");

It works in the same Java code as above. It tries to find a start position right after depCity=. Then matches anything but as little as possible until it reaches a point facing & or end of input.