How to Split Comma-Separated Text with Quotes Using Regular Expressions?

Splitting Comma-Separated Text with Quotes

In certain scenarios where text data contains comma-separated values, it becomes necessary to split the data based on commas. However, challenges arise when the data contains strings with embedded commas within quotes.

To address this, a versatile solution is to employ a regular expression that specifically targets commas located outside of double quotes:

str.split(",(?=(?:[^\"]*\"[^\"]*\")*[^\"]*$)");

Dissecting this regex:

• :, represents the target comma between data values.
• (?=...$) is a look-ahead assertion, indicating that the comma must be followed by the remaining expression.
• (?:[^"]*"[^"]*")* matches zero or more repetitions of pairs of double quotes, ensuring that any embedded commas are excluded from the split.
• [^"]* corresponds to any non-quote characters after the last double quote or the beginning of the string.

Alternatively, the same regex can be written in a more readable format using the (?x) modifier, which allows multi-line expressions to enhance readability:

String[] arr = str.split("(?x)   " + 
                     ",          " +   // Split on comma
                     "(?=        " +   // Followed by
                     "  (?:      " +   // Start a non-capture group
                     "    [^\"]* " +   // 0 or more non-quote characters
                     "    \"     " +   // 1 quote
                     "    [^\"]* " +   // 0 or more non-quote characters
                     "    \"     " +   // 1 quote
                     "  )*       " +   // 0 or more repetition of non-capture group (multiple of 2 quotes will be even)
                     "  [^\"]*   " +   // Finally 0 or more non-quotes
                     "  $        " +   // Till the end  (This is necessary, else every comma will satisfy the condition)
                     ")          "     // End look-ahead
                         );

This solution effectively resolves the issue of splitting comma-separated text while preserving the integrity of strings containing commas enclosed within double quotes.

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