Because in my application I also want to give the user the option to use no stopword-filter. Otherwise if no WVTConfiguration.STEP_WORDFILTER is set, a default-stopword-filter will be executed which filters all 3-character-words which isn't what I want.
Hope someone can help me.
Answer by Ingo Mierswa:
I must admit that I don't see any problem with the line
StopWordFilterFile stopfilter = new StopWordFilterFile(new FileReader(new File(Constants.STOPWORDS_PATH + filename)), false);
The constructor is still there and therefore this should not be problem. Although the problem might be that we changed the way text processing should be performed: now inner operators should be used instead of the one big WVToolOperator in previous releases. The single big operator is now deprecated and will no longer be supported in future versions. Maybe this is the reason for the problem.
Instead of using the method "setMinNumChars" you could now use the operator "TokenLengthFilter".
I would really recommend to redefine you text processing process in the GUI by using inner operators (have a look at the samples delivered together with the text plugin) and change you program according to this new architecture. It is actually more convenient and more powerful now.
How to load processes in XML from the forum into RapidMiner: Read this!