How to extract parameters from a given url

In Java I have:

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

I want to get values of depCity parameters (PAR,NYC).

So I created regex:

String regex = "depCity=([^&]+)";
Pattern p = Pattern.compile(regex);
Matcher m = p.matcher(params);

m.find() is returning false. m.groups() is returning IllegalArgumentException.

What am I doing wrong?