Using split in Java String

Question

I need to split a String with dot '.'but with one catch as explained below For example, if a String is like this

   String str = "A.B.C"

then, splitting with dot, will give A,B and C .

But if the some part is marked with single inverted comma, then split should ignore it

String str = "A.B.'C.D'"

then, splitting with dot, should give A,B and CD .

How can I achieve this?

Answer 1

If the String is always in the given format, you could try : \\\\.(?![A-Za-z]') as regex

demo here

Answer 2

First, split at ' and afterwards, if any of the split results end in . , split at . as well again.

"A.B.'C.D'"
=>
"A.B.", "C.D"
=> "A", "B", "C.D"

Java 8 Example

public static void main(String[] args) {
    final String str = "A.B.'C.D'";
    final List<String> result = new ArrayList<>();

    for (String singleQuoteSplitResultArrayElement : str.split("'")) {
        if (singleQuoteSplitResultArrayElement.endsWith(".")) {
            Collections.addAll(result, singleQuoteSplitResultArrayElement.split("\\."));
        } else {
            result.add(singleQuoteSplitResultArrayElement);
        }
    }

    System.out.println(result.stream().collect(Collectors.joining(", ")));
}

Answer 3

What you can do is as follows - will work with single letter and multiple letter tokens:

String input = "A.B.'C.D'";
//                                              | not following capital letter(s) and '
//                                              |           | dot (escaped)
//                                              |           |  | not followed by 
//                                              |           |  | capital letter(s) and '
System.out.println(Arrays.toString(input.split("(?<![A-Z]+?')\\.(?![A-Z]+?')")));

Output

[A, B, 'C.D']

Note

If you want it case-insensitive, prepend (?i) to the Pattern : (?i)(?<![AZ]+?')\\\\.(?![AZ]+?')")

Answer 4

I don't know of a method in the standard library that does this. It is not too difficult to write yourself, though:

public static String[] splitByDots(String s)
{
    List<String> ss = new ArrayList<>();
    boolean inString = false;
    int start = 0;

    for (int p = 0; p < s.length(); p++) {
        char ch = s.charAt(p);
        if (ch == '\'') {
            inString = !inString;
        }
        else if (ch == '.') { 
            if (!inString) {
                ss.add(s.substring(start, p));
                start = p + 1;
            }
        }
    }

    ss.add(s.substring(start));
    return ss.toArray(new String[ss.size()]);
}

If you want to trim whitespace or remove the quote characters, you will have to tweak the above code a bit, but otherwise it does what you asked for.