stripping elements of different length from a file name java

Hi: As a company we get a lot of orders sent in csv format by email. I use  a third party  program called 'attachment save'  which runs in outlook and saves all attachments to a particular directory. Since it is not unknown for the files from different customers to have the same name, the program adds the date. Thus an attached file j031251.csv  is saved as J0312512016-01-27 12-11.csv .
I then use java to pick out files from a certain customer (in this case always has "wp201" in his filename:

for (int i = 0; i < files.length; i++) {
            fileName = files(i).getName();   // (i put in brackets not parenthesis)
            if(fileName.contains("WP201")){
            //rename file to take date & time off    
             String abc = new String(fileName);
             String xyz = new String(abc.substring(0,(abc.length()-20))+abc.substring((abc.length()-4),abc.length()))  ;            
            //end rename file to take date & time off    
               
                File currentFile = new File(dir + "\\" + abc);
                           success = currentFile.renameTo(new File(dew + "\\" + xyz));
                if(success){        
                    System.out.println("File Copied: "+ currentFile);
                    currentFile.delete();
                }
                else System.out.println("NOT Copied: " + currentFile);          
           }
        }    
Which strips out the date and puts the file in a specific folder. It does this by counting back from the end of the file; easy as the date is always 16 characters.
However, now another customer wants special treatment; but his file is the same as a lot of other peoples files. 'Attachment save' will allow me to insert the senders address like so: "J031251XXXcustomer.co.ukYYY2016-01-27 12-11.csv", where I insert XXX and YYY as delimiters, but can choose anything. Is there a way of stripping out everything after the XXX but BEFORE the ".csv"? This is because , of course, customer addresses will be of different length and file types will be different.