Can I use an String array within split() to specifier delimiters?

user_1488434 0
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New to java/coding and trying to get to grips with it so thank you in advance for the help!

I have this string "s" I am splitting using a set of operators as delimiters.

String[] workableParts = s.split("(?<=[-+*/%^=])|(?=[-+*/%^=])");

I'm storing each split within the workableParts array with the delimiters also stored as part of the array - so for instance an input of 7+7 would be stored as:

workableParts[0]="7" workableParts[1]="+" workableParts[2]="7"

I also use this operator array elsewhere:

private String[] ops = {"-","+","*","/","%","^","="};

Is there a way I can use this to replace the text in the split above but maintain the same effect? The idea being that if I add operators at a later date I only have to update them in one place.

Many thanks,

Sam

delimiter arrays split java
2 Answers

One possible option is to convert your string array to a string using Arrays.toString(ops); and use that in the regex expression. This returns the string of the form [-,+,*,/,...].

Now, you can replace the , with an empty string "" and use the substring in your regex.

private String[] ops = {"-","+","*","/","%","^","="};
String joinedOps = Arrays.toString(strArray);
joinedOps = joinedOps.substring(1, str.length()-1).replace(",", "");
String regex = "...."+joinedOps+"...";
user_72528610

You could do something like this. Define you own split method and build the regex inside of it. When you change the ops array you will modify the regex.

Note: You must use caution in the placement of the ops so that they don't construct an unexpected character class. E.g. - should be at the front and ^ should never be.

static String[] ops = { "-", "+", "*", "/", "%", "^", "=" };

public static void main(String[] args) {
        String s = "7+7-8^2";

        String[] workableParts = opSplit(s);        
        System.out.println(Arrays.toString(workableParts));     
}

Prints

[7, +, 7, -, 8, ^, 2]

The method


public static String[] opSplit(String s) {
    String op = String.join("", ops);
    String regex = "(?<=[" + op + "])|(?=[" + op + "])";
    return s.split(regex);
}
user_15525340
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