In my Java application I need to find indices and split strings using the same "target" for both occasions. The target is simply a dot.

Finding indices (by indexOf and lastIndexOf) does not use regex, so

String target = "."; String someString = "123.456"; int index = someString.indexOf(target); // index == 3

gives me the index I need.

However, I also want to use this "target" to split some strings. But now the target string is interpreted as a regex string. So I can't use the same target string as before when I want to split a string...

String target = "."; String someString = "123.456"; String[] someStringSplit = someString.split(target); // someStringSplit is an empty array

So I need either of the following:

  1. A way to split into an array by a non-regex target
  2. A way to "convert" a non-regex target string into a regex string

Can someone help? Would you agree that it seems a bit odd of the standard java platform to use regex for "split" while not using regex for "indexOf"?

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3 Answers

You need to escape your "target" in order to use it as a regex. Try 

String[] someStringSplit = someString.split(Pattern.quote(target));

and let me know if that helps.

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You can try this one.

String target = "."; String someString = "123.456"; StringTokenizer tokenValue = new StringTokenizer(someString, target); while (tokenValue.hasMoreTokens()) { System.out.println(tokenValue.nextToken()); }
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String::split do split without regex if the regex is:

  • a one-char String and this character is not one of the RegEx's meta characters .$|()[{^?*+\\
  • two-char String and the first char is the backslash and the second is not the ascii digit or ascii letter.

Please see String::split() source code for details.

For escaped '.' target it is going to be split without regex.

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