Retrieving string in between two characters

Question

I have a string, and if the string contains a special character(that i have chosen) such as "+" i want to split the string basically and take the string after it until it encounters another special character such as another "+" or "-" sign(keep in mind that these are special characters only because i want them to be).

So lets say i have this string:

String strng = "hi+hello-bye/34";

so i want what ever method you use to solve this problem to some way return the strings hello or bye or 34 alone. And if the string hand two "+" signs i also want it to return first string after those two "+" characters.

so something like this:

strng.split("\\+"); 

but instead of it returning "hello-bye/34" it only returns "hello".

Answer 1

One option here is to split the input string on the multiple special character delimiters you have in mind, while retaining these delimiters in the actual split results. Then, iterate over the array of parts and return the part which occurs immediately after the special delimiter of interest.

Here is a concise method implementing this logic. I assume that your set of delimiters is +, -, * and /, though you can easily change this to whatever you wish.

public String findMatch(String input, String delimiter) {
    String[] parts = input.split("((?<=[+\\-*/])|(?=[+\\-*/]))");
    String prev = null;
    for (String part : parts) {
        if (delimiter.equals(prev)) {
            return part;
        }
        prev = part;
    }

    return null;   // default value if no match found
}

Note: This method will return null if it iterates over the split input string and cannot find the special delimiter, or perhaps finds it as the last element in the array with no string proceeding it. You are free to change the default return value to whatever you wish.