Splitting a String in Java by multiple regex

Question

I want to string split the following String

String ToSplit = "(2*(sqrt 9))/5";

into the following array of String:

String[] Splitted = {"(", "2", "*", "(", "sqrt", "9", ")", ")", "/", "5"};

To do this I use:

String[] Splitted = ToSplit.split("(?<=[^\\w\\s])(?=\\w)|(?<=\\w)(?=[^\\w\\s])|(?<=[^\\w\\s])(?=[^\\w\\s])|\\s+");

and it works perfectly, BUT, in other tests it envolves doubles, for example

String toSplit = " 2*sqrt(3.0) ";

and I want to split it this way:

String[] Splitted = {"2", "*", "sqrt", "(", "3.0", ")"};

But it is coming out

String[] Splitted = {"2", "*", "sqrt", "(", "3", ".", "0", ")"};

So, as you can see, in spite of having just the element "3.0" I get three elements {"3", ".", "0"}

How can I solve this issue?

Thanks in advance.

Answer 1

As an option, you can just concatenate the elements you need (this is just a sample code, I did not test it):

String[] splitted = {"2", "*", "sqrt", "(", "3", ".", "0", ")"};
List<String> a = new ArrayList<>();
for (int i = 0; i < splitted.length(); i++) {
    if (splitted[i].equals(".") && i > 0 && i < splitted.length() - 1) {
       a.set(a.size() - 1, a.get(i - 1) + "." + splitted[i + 1]);
       i+=2;
    } else {
       a.add(splitted[i]);
    }
}

//The elements you need are on the 'a' list.

But I suggest you following John Bollinger's advice. Write your own simple parser to split the input String. That is not that hard.