Java Splitting a String

Question

I have this string

G234101,Non-Essential,ATPases,Respiration chain complexes,"Auxotrophies, carbon and",PS00017,2,IONIC HOMEOSTASIS,mitochondria.

That I have been trying to split in java. The file is comma delimeted but some of the strings have commas within them and I don't want them to get split up. Currently in the above example

"Auxotrophies, carbon and"

is getting split into two strings.

Any suggestions on how to best split this up by comma's. Not all of the strings have the " " for example the following string:

G234103,Essential,Protein Kinases,?,Cell cycle defects,PS00479,2,CELLULAR COMMUNICATION/SIGNAL TRANSDUCTION,cytoplasm.

This is why character encodings are used. Do not place it in quotes, change the comma to something like %2C, then decode after. — Vetsin
– Vetsin, Commented May 23, 2012 at 22:39
I think you could tokenize first using " and iterating over all tokens, again tokenize using , — Garbage
– Garbage, Commented May 26, 2012 at 16:46

Malcolm Smith · Accepted Answer · 2012-05-25 08:09:30Z

2

http://opencsv.sourceforge.net/

But if you really do need to reinvent the wheel (homework), you need to use a more complicated regular expression than just "what,ever".split(","). It's not simple though. And you might be better off creating your own custom Lexer. http://en.wikipedia.org/wiki/Lexical_analysis

This isn't too hard in your case. As you process your text character by character you just need to keep track of opening and closing quotes to decide when to ignore commas and when to act on them.

Also see StreamTokenizer for a built-in configurable Lexer - you should be able to use this to meet your requirements.

edited May 25, 2012 at 8:09

answered May 23, 2012 at 22:41

Malcolm Smith

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1 Comment

Ray Toal Over a year ago

+1 An existing CSV parser is the only reasonable answer for this task, unless it is homework. :)

mart2001 · Accepted Answer · 2012-05-23 22:42:36Z

1

I would think that this would be a multi step process. First, find all the comma's in quotes from your original string, replace it with something like {comma}. You can do this with some regex. Then on the new string, split the new string with the comma symbol(,). Then go through your list, and replace the {comma} with the comma symbol {,}.

answered May 23, 2012 at 22:42

mart2001

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Chii Over a year ago

what if the text in one of the csv columns contains the literal '{comma}'? replacing the comma doesn't actually solve the problem. It might make the problem less likely, but this is a hack.

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