Replacing single '\' with '\\' in Java

Question

How do I replace a single '\' with '\\'? When I run replaceAll() then I get this error message.

Exception in thread "main" java.util.regex.PatternSyntaxException:
                           Unexpected internal error near index 1 \
                                                                  ^
    at java.util.regex.Pattern.error(Pattern.java:1713)
    at java.util.regex.Pattern.compile(Pattern.java:1466)
    at java.util.regex.Pattern.<init>(Pattern.java:1133)
    at java.util.regex.Pattern.compile(Pattern.java:823)
    at java.lang.String.replaceAll(String.java:2190)
    at NewClass.main(NewClass.java:13)
Java Result: 1

My code:

public class NewClass {
    public static void main(String[] args) {
        String str = "C:\\Documents and Settings\\HUSAIN\\My Documents\\My Palettes";
        str = str.replaceAll("\\", "\\\\");
        System.out.println(str);
    }
}

Answer 1

\ is also a special character in regexp. This is why you should do something like this:

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