Question

The following code fragment in Java:

"\\\\".replaceAll("\\\\", "\\");

throws the exception:

java.lang.StringIndexOutOfBoundsException: String index out of range: 1 (NO_SOURCE_FILE:0)

The javadoc on replaceAll does include a caveat on the use of backslashes and recommends using Matcher.replaceAll or Matcher.quoteReplacement. Does anybody have a snippet on how to replace all occurrences of two backslashes in a string with a single backslash ?

clarification

The actual literal shown above is only an example, the actually string can have many occurrences of two consecutive backslashes in different places.

Answer 1

You can simply do it with String#replace(): –

"\\\\".replace("\\\\", "\\")

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String#replaceAll takes a regex as parameter. So, you would have to escape the backslash twice. Once for Java and then for Regex. So, the actual replacement using replaceAll would look like: –

"\\\\".replaceAll("\\\\\\\\", "\\\\")

But you don’t really need a replaceAll here.