Java URLDecoder throws exception when used with a string containing a %

Question

I have a problem with the URLDecoder of Java. I am escaping a String in JavaScript, and send it to a java servlet. Then I decode the escaped String with the following line: ``` URLDecoder.decode(request.getParameter("text"), "UTF-8"); ``` This works fine for every special characters I have tried, the only one making problems is the '%'. Everytime I use this character in the string, I get the following exception: ``` java.lang.IllegalArgumentException: URLDecoder: Incomplete trailing escape (%) pattern java.net.URLDecoder.decode(URLDecoder.java:187) at.fhv.students.rotter.ajax.count.CountServlet.doGet(CountServlet.java:31) javax.servlet.http.HttpServlet.service(HttpServlet.java:621) javax.servlet.http.HttpServlet.service(HttpServlet.java:722) ``` Is this a known bug? Or is it really my mistake?

Accepted Answer

It is not a bug. You send a wrong encoded String. The `%`-sign has to be encoded as `%25`

If you call request.getParameter(), I think you get a decoded String.

Java URLDecoder throws exception when used with a string containing a %

Solution

Problem