Weirdness.

    public void localiseFile(File m3uFile, boolean replaceInsteadOfCopy) throws FileNotFoundException
    {
        try
        {
            if(!m3uFile.exists())
                throw new FileNotFoundException("M3U file at path doesn't exist: " + m3uFile.toString());

            File saveFile = new File(getSaveFilePathFromLoadFilePath(m3uFile.getCanonicalPath()));
            saveFile.mkdirs();

            if(saveFile.exists())
                saveFile.delete();

            saveFile.createNewFile();

            DataInputStream input = new DataInputStream(new FileInputStream(m3uFile));
            BufferedReader reader = new BufferedReader(new InputStreamReader(input));

            FileWriter output = new FileWriter(saveFile, true);
            PrintWriter writer = new PrintWriter(output);

            boolean firstLine = true;

            try
            {
                for(String line = ""; line != null; line = reader.readLine())
                    if(firstLine)
                    {
                        writer.print(localiseFileLine(m3uFile.getParentFile(), line));
                        firstLine = false;
                    }
                    else
                        writer.println(localiseFileLine(m3uFile.getParentFile(), line));
            }
            finally
            {
                input.close();
                reader.close();
                writer.flush();
                writer.close();
                output.close();
            }

            if(replaceInsteadOfCopy)
            {
                m3uFile.delete();
                saveFile.renameTo(m3uFile);
            }
        }
        catch(IOException exception)
        {
            if(exception instanceof FileNotFoundException)
                throw (FileNotFoundException)exception;

            throw new RuntimeException("Unexpected IO exception", exception);
        }

        jLabel1.setText("Localised!");
    }