Removing file extension using REGEX

Question

                // User didn't add the XLS extension; add it automatically
                if (file.getName ().lastIndexOf (".") > 0)
                    fileName = file.getName ().toLowerCase ().replaceAll (".*$", ".xls");
                    System.out.println ("*** ALREADY HAS AN EXTENSION ***");
                    System.out.println ("Renamed to " + fileName);
                ...What I'm trying to do is remove a file extension from a string and add my own. For example, in my application, I'm checking to see if there is a period in the file.getName() string. If there is, I want to replace anything from the period on with nothing, but I don't think my regular expression is right.
If I type in "file.txt", I get:
*** ALREADY HAS AN EXTENSION ***
Renamed to .xls.xls
Basically, my regular expression is incorrect, but I don't see what I'm missing.

Answer 1

    private void saveFile ()
        useFileFilter (".xls", "Excel Files (*.xls)");
        String fileName;
        int returnVal = fc.showSaveDialog (this);
        if (returnVal == JFileChooser.APPROVE_OPTION)
            File file = fc.getSelectedFile ();
            if (file.getName ().endsWith (CustomFilter.getExtension()))
                // User kept the XLS extension
                fileName = file.getName ();
                System.out.println ("Saving " + fileName);
            else
                // User added their own extension; change it
                if (file.getName ().lastIndexOf (".") != -1)
                    fileName = file.getName ().replaceAll ("\\..+", "") + CustomFilter.getExtension();
                    System.out.println ("*** ALREADY HAS AN EXTENSION ***");
                    System.out.println ("Renamed to " + fileName);
                // User didn't add an extension; add it
                else
                    fileName = file.getName () + CustomFilter.getExtension();
                    System.out.println ("*** Saving " + fileName);
        else
            System.out.println ("User cancelled the dialog.");
    }I found that your regex works best in this case.fileName = file.getName ().replaceAll ("\\..+", "") + CustomFilter.getExtension();If I try to save a file as tEsT.tar.gz, my output is:
*** ALREADY HAS AN EXTENSION ***
Renamed to tEsT.xls.
If I used the other user's example:fileName = file.getName ().replaceAll ("\\.[^.]*$", "") + CustomFilter.getExtension();it wouldn't be correct. If I entered a filename such as tEsT.tar.gz, my output would be:
*** ALREADY HAS AN EXTENSION ***
Renamed to tEsT.tar.xls