String replaceAll method removes backslashes in replacement string

[Raja Kannappan]

When I use String replaceAll() method, it removes all the backslashes in my replacement string. The matcher class in jdk explicity removes all the backslashes. Is there any way to avoid this?

when I do str.replaceAll("xyz", "c:\\temp\\xyz"); it replaces xyz with ctempxyz instead of c:\temp\xyz.

Does anyone know how to replace the string without replacing slashes? Any help is greatly appreciated. Thanks.
[ February 15, 2008: Message edited by: Raja Kannappan ]

[Garrett Rowe]

You have to use four backslashes:

public class Replace
{
   public static void main(String[] args)
   {
      String aStr = "xyz";
      String replacement = aStr.replaceAll("xyz", "c:\\\\temp\\\\xyz");
      System.out.println(replacement);
   }
}

[Raja Kannappan]

I tried that before and it worked, but I had problems converting my input replacement string (coming from user) to the desired format. Previously, I tried replacement = replacement.replaceAll("\\", "\\\\"); but it gave me error. Now, i tried replacement = replacement.replaceAll("\\\\", "\\\\\\\\"); and it works fine.

The problem is solved but I don't understand why we have to put four slashes. I understand that we put two back slashes instead of one backslash as a escape
construct so that second backslash is actually taken as a character. But, I don't understand why we have to use four slashes. Can anyone please explain?

Thanks.

[Garrett Rowe]

[Raja]:But, I don't understand why we have to use four slashes. Can anyone please explain?


Obviously a forward slash is a special character in a String, but a forward slash is also a special character in a regex. The forward slash has to be escaped with another forward slash in order for the regex engine to view it as a literal '\' character. Both forward slashes have to be escaped so that the String class views them as literal '\'. Therefore you end up needing four forward slashed.

[Raja Kannappan]

Thanks Garrett. That helps!
[ February 17, 2008: Message edited by: Raja Kannappan ]

[Stefan Wagner]

replace foreward by backward in Garretts text.

slash=forward slash=/=uphill
backslash=\=downhill

It's a latin alphabet, so you have to read from left to right.

[Garrett Rowe]

[Stefan]: replace foreward by backward in Garretts text.

slash=forward slash=/=uphill
backslash=\=downhill

It's a latin alphabet, so you have to read from left to right.

Thanks for the correction. I always get those confused. Now how do I remember the difference between a stalactite and a stalagmite.

[Stefan Wagner]

Originally posted by Garrett Rowe:

Thanks for the correction. I always get those confused. Now how do I remember the difference between a stalactite and a stalagmite.

The m in stalagmite has 3 feet at the bottom, and the t in stalagtite has a hook at the top.

[John O'Hanley]

There is an alternative to replaceAll that avoids regular expressions:

The String.replace(CharSequence, CharSequence) method

See as well :
javapractices.com