public static void testThis(String[] args)
	{
		boolean decode = false;

		if (args.length == 0) {
			System.out.println("usage:  java Base64 [-d[ecode]] filename");
			System.exit(0);
		}
		for (int i=0; i<args.length; i++) {
			if ("-decode".equalsIgnoreCase(args[i])) decode = true;
			else if ("-d".equalsIgnoreCase(args[i])) decode = true;
		}

		String filename = args[args.length-1];
		File file = new File(filename);
		if (!file.exists()) {
			System.out.println("Error:  file '" + filename + "' doesn't exist!");
			System.exit(0);
		}

		if (decode)
		{
			char[] encoded = readChars(file);
			byte[] decoded = decode(encoded);
			writeBytes(file, decoded);
		}
		else
		{
			byte[] decoded = readBytes(file);
			char[] encoded = encode(decoded);
			writeChars(file, encoded);
		}
	}