Ordering of values in HttpServletRequest.getParameterValues()

Question

HttpServletRequest.getParameterValues() returns a String[] containing all values of a given HTTP request parameter. Does anyone know if the order o

Answer 1

The javadoc for ServletRequest (v2.5 javadoc) does not mention anything about the ordering of values for that method. As such, I wouldn't rely on the order being preserved.

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Update: also checked the spec document for 2.5, contains the following information relating to getParameterValues(). It does not mention anything about ordering with respect to the query string, so I think the behaviour you are seeing is implementation detail, not defined as part of the interface.

The parameters are stored as a set of name-value pairs. Multiple parameter values can exist for any given parameter name. The following methods of the ServletRequest interface are available to access parameters:

• getParameter
• getParameterNames
• getParameterValues
• getParameterMap

The getParameterValues method returns an array of String objects containing all the parameter values associated with a parameter name. The value returned from the getParameter method must be the first value in the array of String objects returned by getParameterValues. The getParameterMap method returns a java.util.Map of the parameter of the request, which contains names as keys and parameter values as map values.

For future reference, the Java Servlet specs can be downloaded from Sun, I mean Oracle's website. You can double check the specific servlet version you're interested in there.