如何在Java中用/替换\\？

Question

I tried with following regex, but it didn't work.

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

Exception:

java.util.regex.PatternSyntaxException: Unexpected internal error near index 1 \\ ^ at java.util.regex.Pattern.error(Unknown Source) at java.util.regex.Pattern.compile(Unknown Source) at java.util.regex.Pattern.(Unknown Source) at java.util.regex.Pattern.compile(Unknown Source) at java.lang.String.replaceAll(Unknown Source)

Answer 1

Your code should not even compile.

"\\" escapes the " so that the string continues. Writing String h = "\\"hello\\""; makes the string h contain "hello" .

If we change then change it to it to "\\\\" (escaping the backslash) we run into another problem. The regular expression then tries to escape the next character. For example writing "\\\\d+" is a valid regular expression (matching digits).

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In you case however you do not need regular expressions at all. Just use the replace(char, char) method of the string, it replaces all characters.

myString.replace('\\', '/');

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By the way, if you are replacing paths, you should look at File.separator to get the systems path separator character .

Answer 2

Sometimes you need 4 slashes, because backslash is an escape character for regex as well. Try

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