regexp split string by commas and spaces, but ignore the inside quotes and parentheses

This will work only for non-nested parentheses:

    $regex = <<<HERE
    /  "  ( (?:[^"\\]++|\\.)*+ ) "
     | '  ( (?:[^'\\]++|\\.)*+ ) '
     | ( ( [^)]*                  ) )
     | [s,]+
    /x
    HERE;

    $tags = preg_split($regex, $str, -1,
                         PREG_SPLIT_NO_EMPTY
                       | PREG_SPLIT_DELIM_CAPTURE);

The ++ and *+ will consume as much as they can and give nothing back for backtracking. This technique is described in perlre(1) as the most efficient way to do this kind of matching.

Here's a sample of a parser that would implement your need :

public static List<String> splitter(String input) {
    int nestingLevel=0;
    StringBuilder currentToken=new StringBuilder();
    List<String> result = new ArrayList<>();
    for (char c: input.toCharArray()) {
        if (nestingLevel==0 && c == '/') { // the character is a separator !
            result.add(currentToken.toString());
            currentToken=new StringBuilder();
        } else {
            if (c == '(') { nestingLevel++; }
            else if (c == ')' && nestingLevel > 0) { nestingLevel--; }

            currentToken.append(c);
        }
    }
    result.add(currentToken.toString());
    return result;
}

You can try it here.

Note that it doesn't lead to the expected output you posted, but I'm not sure what algorithm you were following to obtain such result. In particular I've made sure there's no "negative nesting level", so for starters the / in "Mango 003 )/( ASDJ" is considered outside of parenthesis and is parsed as a separator.

Anyway I'm sure you can tweak my answer much more easily than you would a regex answer, the whole point of my answer being to show that writing a parser to handle such problems is often more realistic than to bother trying to craft a regex.

Use a CSV parser like OpenCSV to take care of things like commas in quoted elements, values that span multiple lines etc. automatically. You can use the library to serialize your text back as CSV as well.

String str = "value1, value2, value3, value4, "value5, 1234", " +
        "value6, value7, "value8", value9, "value10, 123.23"";

CSVReader reader = new CSVReader(new StringReader(str));

String [] tokens;
while ((tokens = reader.readNext()) != null) {
    System.out.println(tokens[0]); // value1
    System.out.println(tokens[4]); // value5, 1234
    System.out.println(tokens[9]); // value10, 123.23
}