Bug in util.introspection.ClassMap (with Fix)

[Sven Meier]

Hi

I have found a bug in

 org.apache.velocity.util.introspection.ClassMap

and would like to suggest a fix for it.

Please see below and advise if you need more information - feedback
appreciated!

Thanks a bunch

Sven

=======================================================================

Nightly build :

 http://jakarta.apache.org/builds/jakarta-velocity/nightly/2002-03-14/

Type:

 org.apache.velocity.util.introspection.ClassMap

Method:

 private static String makeMethodKey(String method, Object[] params)

Description:

 This method calculates a key for given method-name and parameters.
 It's really just a helper but it has a side-effect. It changes the
 given array's content!

 The bug manifests itself as described in

  http://www.mail-archive.com/velocity-user@jakarta.apache.org/msg05999.html

 If you put a null-value in a context's collection or a business-
 object returns null then makeMethodKey turns the null into
 ClassMap.OBJECT. This only happens the first time when the key
 hasn't been computed before.

Resolution:

 Remove the side-effect :

 =========== diff ===============================

 D:\sven\changes>diff ClassMap.java ..\original\ClassMap.java
 275,282c275,276
 <             // 20020314 [EMAIL PROTECTED]
 <             // Instead of changing the input params-array with
 <             //   params[j] = OBJECT
 <             // we keep the 'null'-check local
 <             Object arg = params[j];
 <             if (arg == null) {
 <                 arg = OBJECT;
 <             }
 ---
 >             if (params[j] == null)
 >                 params[j] = OBJECT;
 284c278
 <             methodKey.append(arg.getClass().getName());
 ---
 >             methodKey.append(params[j].getClass().getName());

 =========== result ===============================

    private static String makeMethodKey(String method, Object[] params)
    {
        StringBuffer methodKey = new StringBuffer().append(method);

        for (int j = 0; j < params.length; j++)
        {
            // 20020314 [EMAIL PROTECTED]
            // Instead of changing the input params-array with
            //   params[j] = OBJECT
            // we keep the 'null'-check local
            Object arg = params[j];
            if (arg == null) {
                arg = OBJECT;
            }

            methodKey.append(arg.getClass().getName());
        }

        return methodKey.toString();
    }





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