Open String filepath to BufferedReader (Doesn't include imports).

private static BufferedReader openFile(String filename) throws FileNotFoundException

    /**
     * Opens a file into a BufferedReader.
     *
     * @param filename A file to read.
     * @return A BufferedReader for reading the file.
     * @throws FileNotFoundException
     */
    private static BufferedReader openFile(String filename) throws FileNotFoundException {
        return new BufferedReader(new FileReader(filename));
    }