Removing whitespace in Java string?

Question

Hi guys, I'm writing a parser for some LISP files. I'm trying to get rid of leading whitespace in a string. The string contents are along the lines of:

         :FUNCTION (LAMBDA
                   (DELTA
                    PLASMA-IN-0)
                 (IF
                  (OR
                   (>=
                    #61=(+
                         (*
                          1
                          DELTA)
                         PLASMA-IN-0)
                    100)
                   (<=
                    #61#
                    0))
                  PLASMA-IN-0
                  #61#))

The tabs are all printed as 4 spaces in the file, so I want to get rid of these leading tabs.

I tried to do this: string.replaceAll("\\s{4}", " ") - but it had no effect at all on the string.

Does anyone know what I'm doing wrong? Is it because it is a multi-line string?

Thanks

Answer 1

String.trim();

Should work.

Answer 2

Your original regular expression didn't work because you forgot to escape the backslash. This should do what you were originally trying to do:

string.replaceAll("\\s{4}", " ")

EDIT: I didn't realize that you did not, in fact, forget to escape the backslash, and that Stack Overflow "ate" one of your backslashes, as Alan Moore pointed out in one of the comments to this answer (the only difference between "\s" and "\\s" is backticks around the text). That being said, my original answer isn't going to be of much help to you, so...

In order for this to be effective, you have to do something with the output from String#replaceAll, since it returns a new String instead of modifying the existing one (Strings are immutable, as William Brendel noted in his comment to your question).

string = string.replaceAll("\\s{4}", " ")

Since this answer didn't actually add anything of value, instead of deleting it, I'm making it Community Wiki.