Java: splitting a comma-separated string but ignoring commas in quotes

Question

I have a string vaguely like this:

foo,bar,c;qual=\"baz,blurb\",d;junk=\"quux,syzygy\"

that I want to split by commas -- but I need to igno

Answer 1

I was impatient and chose not to wait for answers... for reference it doesn't look that hard to do something like this (which works for my application, I don't need to worry about escaped quotes, as the stuff in quotes is limited to a few constrained forms):

final static private Pattern splitSearchPattern = Pattern.compile("[\",]"); 
private List<String> splitByCommasNotInQuotes(String s) {
    if (s == null)
        return Collections.emptyList();

    List<String> list = new ArrayList<String>();
    Matcher m = splitSearchPattern.matcher(s);
    int pos = 0;
    boolean quoteMode = false;
    while (m.find())
    {
        String sep = m.group();
        if ("\"".equals(sep))
        {
            quoteMode = !quoteMode;
        }
        else if (!quoteMode && ",".equals(sep))
        {
            int toPos = m.start(); 
            list.add(s.substring(pos, toPos));
            pos = m.end();
        }
    }
    if (pos < s.length())
        list.add(s.substring(pos));
    return list;
}

(exercise for the reader: extend to handling escaped quotes by looking for backslashes also.)

Answer 2

I would do something like this:

boolean foundQuote = false;

if(charAtIndex(currentStringIndex) == '"')
{
   foundQuote = true;
}

if(foundQuote == true)
{
   //do nothing
}

else 

{
  string[] split = currentString.split(',');  
}

Answer 3

Try a lookaround like (?!\"),(?!\"). This should match , that are not surrounded by ".

Answer 4

Rather than use lookahead and other crazy regex, just pull out the quotes first. That is, for every quote grouping, replace that grouping with __IDENTIFIER_1 or some other indicator, and map that grouping to a map of string,string.

After you split on comma, replace all mapped identifiers with the original string values.

Answer 5

http://sourceforge.net/projects/javacsv/

https://github.com/pupi1985/JavaCSV-Reloaded (fork of the previous library that will allow the generated output to have Windows line terminators \r\n when not running Windows)

http://opencsv.sourceforge.net/

CSV API for Java

Can you recommend a Java library for reading (and possibly writing) CSV files?

Java lib or app to convert CSV to XML file?