Splitting on multiple delimiters but keep the delimiters on the same string

Question

I want help with regular expressions to solve the following problem:

I have a string such as \"1£23$456$£$\"

when I split on it I want the output in my strin

Answer 1

You probably want this

Matcher m = Pattern.compile("[^$£]*(\\$|£)").matcher(input);

Answer 2

Use the more powerful Matcher functionality instead of String.split. The below code should work, but has not been optimized:

Pattern pattern = Pattern.compile("\\d*(\\$|£)");

String input = "1£23$456$£$";
Matcher matcher = pattern.matcher(input);
List<String> output = new ArrayList<>();
while (matcher.find()) {
    output.add(matcher.group());
}

Printing out output.toString() generates:

[1£, 23$, 456$, £, $]

---

Updated requirements:

1. Also include delimiter characters: +, -, *, and /
2. Non-delimiter characters are only digits with optional spaces before the delimiters.
3. Any such spaces are part of the value, not delimiters themselves.

Use the regular expression: \\d*\\s*[-\\+\\*/\\$£]

That pattern, with this given input:

1£23$456$£$7+89-1011*121314/1 £23 $456 $ £ $7 +89 -1011 * 121314 /

Will generate this output:

[1£, 23$, 456$, £, $, 7+, 89-, 1011*, 121314/, 1 £, 23 $, 456 $, £, $, 7 +, 89 -, 1011 *, 121314 /]

Answer 3

Use a look behind, which is non-consuming:

String[] parts = str.split("(?<=\\D)");

That's all there is to it. The regex means to split "just after every non-digit", which seems to be exactly your intention.

---

Some test code:

String str = "1£23$456$£$";
String[] parts = str.split("(?<=\\D)");
System.out.println( Arrays.toString( parts));

Output:

[1£, 23$, 456$, £, $]