How to replace a specidfic character in a phrase

[Carcharoth]

I want to replace the 3 last characters of file, just before the dot in extension.

I know there is a command to do it but i just can't fine it.

I want it to go like this

 
Var file = self.location.toString();
Var MyVar= ( 3 last characters before extension)
 
 
   If MyVar="_en" replace with "_gr"
 
           else replace with "_en"
 
   end if
 
 

To give you an idea of what i'm trying to do,
In the end i want it to be able to replace "SomePage_en" with "Somepage_gr" and the opposite
Excuse my ignorance in Java but i just started using it today.

[jkmyoung]

Sorry, are you trying to rename a file, or edit a file's contents?
If the former, look at the File.renameTo function.
http://java.sun.com/javase/6/docs/ap...(java.io.File)