Java - replace all instances of path separators with system path separator

Question

I've taken the regex matching both slash and backslash from this answer: Regex to match both slash in JAVA

    String path = "C:\\system/properties\\\\all//";
    String replaced = path.replaceAll("[/\\\\]+", 
        System.getProperty("file.separator"));

However, I get the error:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 1

What is wrong with this regex? Removing + doesn't change anything, the error message is the same...

Answer 1

It is documented in the Javadoc:

Note that backslashes (\) and dollar signs ($) in the replacement string may cause the results to be different than if it were being treated as a literal replacement string; see Matcher.replaceAll. Use Matcher.quoteReplacement(java.lang.String) to suppress the special meaning of these characters, if desired.

So you can try this:

String replaced = path.replaceAll("[/\\\\]+", Matcher.quoteReplacement(System.
            getProperty("file.separator")));

Answer 2

This should work:

String path = "C:\\system/properties\\\\all//";

Edit: modified following contents of assylias' answer

System.out.println(path.replaceAll("(\\\\+|/+)", Matcher.quoteReplacement(System.getProperty("file.separator"))));

End of edit

Output (for me - I use a mac):

C:/system/properties/all/

So it will "normalize" the double separators.