Regex for splitting a string delimited by | when not enclosed on double quotes

Question

I need a regex to count the number of columns in a pipe delimited string in java. The column data will always be enclosed by double quotes or it will be empty.

eg:

"1234"|"Name"||"Some description with ||| in it"|"Last Column"

The above should be counted as 5 columns including one empty column after "Name" column.

Thanks

Answer 1

Here's one way to do it:

String input =
    "\"1234\"|\"Name\"||\"Some description with ||| in it\"|\"Last Column\"";
//  \_______/ \______/\/\_________________________________/ \_____________/    
//      1        2    3                 4                          5

int cols = input.replaceAll("\"[^\"]*\"", "")  // remove "..."
                .replaceAll("[^|]", "")        // remove anything else than |
                .length() + 1;                 // Count the remaining |, add 1

System.out.println(cols);   // 5

IMO it's not very robust though. I wouldn't recommend using regular expressions if you plan on handling escaped quotes, for instance.

Answer 2

Slightly improved the expressions in aioobe's answer:

int cols = input.replaceAll("\"(?:[^\"\\]+|\\.)*\"|[^|]+", "")
                .length() + 1;

Handles escapes in quotes, and uses a single expression to remove everything except the delimiters.