Paranamer does not return parameter names

Question

I am using paranamer.jar to get the parameter names of a method. But it does not get any parameter names.

    Class c = Class.forName("com.soa1.MyClass");
    Class[] argTypes = { java.lang.String.class };
    Method method=ABC.class.getMethod("getData",argTypes);
Paranamer paranamer = new CachingParanamer();
    String[] parameterNames = paranamer.lookupParameterNames(method,false);

Have a look at [this question](http://stackoverflow.com/questions/939194/preserving-parameter-argument-names-in-compiled-java-classes), but it will depend on how you are compiling your code; are you using an IDE? are you compiling from the command line? — Craig, Jun 20 '13 at 01:42
I am using eclipse. Are there any settings that I can change? — Parag Phadtare, Jun 20 '13 at 01:48
To preserve names in the class file for debugging purposes try: "project properties" -> "Java compiler" -> "Add variable attributes to generated class files". But also read @Chris' answer for other possible solutions — Craig, Jun 20 '13 at 01:50

score 3 · Answer 1 · answered Jun 20 '13 at 01:43

Did the parameter names come from somewhere? According to ParaNamer's documentation, it uses several ways to obtain parameter names:

Via a __PARANAMER_DATA field. Obviously, this only works if your class has such a field.
Via debug information in your .class file. Obviously, this only works if your class was compiled with debugging information.
Via a @Named annotation. Obviously, this only works if your method parameters contain such an annotation.

If none of these apply to your class, then sorry, parameter names will not be available.

I am following option 2. But it still does not work. I have the following settings in my eclipse. "project properties" -> "Java compiler" -> "Add variable attributes to generated class files" — Parag Phadtare, Jun 20 '13 at 18:14

score 0 · Answer 2 · answered Jul 03 '13 at 15:06

Use this:

Paranamer paranamer = new AdaptiveParanamer();

Instead this:

Paranamer paranamer = new CachingParanamer();

If are not working yet, tell me, cause I have trouble with paranamer too - after help of a brazilian friend I've learned how it works. See ya!

score 0 · Answer 3 · answered Dec 29 '13 at 10:17

keep the debug information when compiling

if you are compiling with eclipse so check the option keep debug information in project-properties-java compiler

if you are compiling with javac add -g option

and in your code use Paranamer paranamer = new AdaptiveParanamer();

Paranamer does not return parameter names

3 Answers3