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I need to parse complex (non fixed length) csv files to Java objects in order to compare its values. I first tried the Flatform Parsing Framework, i liked the approach of describing the values in an extra (xml) document. Maybe it's the right tool for simple csv (and also flat) files. Nevertheless my csv files contains lines that vary in quantity of fields - sometimes they span across multiple lines. There are also dependencies among those fields.

Here's a little sample: (each type has a certain amount of extra parameters)

    ; <COMMENTS (to be ignored)>
    <NAME>,<TYPE_A>,<DESCRIPTION>,<PARAMETER>
    <NAME>,<TYPE_B>,<DESCRIPTION>,<PARAMETER>,<PARAMETER>
    <NAME>,<TYPE_C>,<DESCRIPTION>,<PARAMETER>,<PARAMETER>,<PARAMETER>,<PARAMETER>
    <NAME>,<TYPE_D>,<DESCRIPTION>,<PARAMETER>,<PARAMETER>,<PARAMETER>,<PARAMETER>, -
                              <PARAMETER>,<PARAMETER>, -
                              <PARAMETER>,<PARAMETER>
    <NAME>,<TYPE_B>,<DESCRIPTION>,<PARAMETER>,<PARAMETER>
    <NAME>,<TYPE_A>,<DESCRIPTION>,<PARAMETER>

So i need something to describe and parse the csv file in a more complex manner. I'm new to this, I've heard about parser generator - is that what I need?

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    There is whole java parser framework (actually, that's a big understatement, but fits here) - take a look at antlr.org Commented Jul 14, 2011 at 7:15
  • Colleagues of mine used to write grammars for the boost.spirit framework (C++). I need to check a Java equivalent. ANTLR seems to be a perfect opportunity - and complex i guess. Commented Jul 14, 2011 at 9:16
  • The fact that you have - that act as line continuations and comments, make it ill suited for a CSV parser. You'd have to rewrite an existing CSV parser to account for them, in which case I'd simply write a small grammar and let JavaCC or ANTLR generate a parser. Commented Jul 14, 2011 at 14:50
  • @Bart: Are you experienced with ANTLR? Is there any sample how to parse text to Java objects? Commented Jul 15, 2011 at 6:27
  • @mamuesstack, yes, I know a little about ANTLR. Could you edit your original question and explain a bit about what type of objects you want to create? Is each line with a different number of <PARAMETER>s a different object? Commented Jul 15, 2011 at 6:33

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Try OpenCSV (see http://opencsv.sourceforge.net/#what-features). It handles embedded carriage returns just fine.

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hmm, the documentation is bad, there are only some standard examples. The parsing of multiple lines works fine. But I guess my csv files vary so much, that I also need to check the parser generators (e.g. ANTLR)
I'm curious: why exactly do you need a parser generator? I mean, I understand if you WANT a parser generater, but NEED is a strong word. They are CSV files. They are generated by some program. There are limits on what the program does (I assume its a sane program).
It's just about the variety of the CSV values. There are exceptions on how the single lines need to be processed. For instance, with OpenCSV I don't know how to recognize fields that are spanned over multiple lines with an '-' (minus) between (line 5 of the sample). A field is always closed by an ',', the whole field set by CR. And as is mentioned before: the documentation isn't that helpful
@Femi, I had a quick look at OpenCSV, but could not find a way to account for commented lines (; ... \n) or to indicate that - \n should be treated as a line continuation. AFAIK, this input isn't CSV.
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One option is to use the Scanner class or you might want to check out the Spring Batch. Ive never actually used SB but given batch jobs often read from simple text files i believe i read it caters for this including all sorts of object mapping.

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In the end I created my own solution using the Scanner class and some RegExp. Thanks!
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You may also try japaki

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Japaki sound interesting. I ended up using the Scanner class and appropriate RegExps to parse the file. Next time, I definitely give Japaki a try

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