Tips for writing a file parser in Java? [closed]

Question

EDIT: I'm mostly parsing "comma-seperated values", fuzzy brought that term to my attention.

Interpreting the blocks of CSV are the main question here.

I know how to read the file into something like a String[] and some of the basic features of String, but I don't think using methods like contains() and analyzing everything character by character will work.

What are some ways I can do this in a smarter way?

Example of a line:

-barfoob: boobs, foob, "foo bar"

Answer 1

Depending on how complicated your "schema" is, a regular expression might be what you want. If there is a lot of nesting then it might be easiest to convert to XML or JSON and use a prebuilt parser.

Answer 2

People are right about standard formats being best practice, but let's set that aside.

Assuming that the example you give is representative, the task is pretty trivial.

You show a line with an initial token, demarked with a colon-space, then a list of comma-separated values. Separate at that first colon-space, and then use split() on the part to the right. Handling of the quotes is trivial, too.

Answer 3

Since the input is "formatted similarly to HTML", then it is likely that your data is best represented using a tree-like structure, and also, it is likely that it is XML or similar to XML.

If this is the case, I propose the smartest way to parse your file is to use an XML parser.

Here are some resources you may find helpful:

• A chapter on XML parsing from Sun: http://java.sun.com/developer/Books/xmljava/ch03.pdf
• An article that might help you get started qucikly: http://onjava.com/pub/a/onjava/2002/06/26/xml.html

HTH

Answer 4

If the XML is valid, I personally prefer using http://www.xom.nu simply because it features a nice DOM model. As pointed out, though, there are parsers in J2SE.

Answer 5

This and digging through wikipedia for related articles will probably suffice.

Answer 6

There's a reason that everyone assumes you're talking about XML: inventing a proprietary text-based file format requires very strong justification in the face of the maturity and easy availability of XML parsers.

And your question indicates that you have very little prior knowledge about parsers (otherwise you'd be writing an ANTLR or JavaCC grammar instead of asking this question) - which is another strong argument against rolling your own, except as a learning experience.