So what are you saying is the problem then? That writing to the BufferedOutputStream for each character is CPU-inefficient and he should be doing this?

    public static void main(String[] args) throws IOException {
        byte[] buffer = new byte[1 << 12];
        for (;;) {
            int nRead = System.in.read(buffer);
            if (nRead == -1) return;
            System.out.write(buffer, 0, nRead);
        }
    }

If so, fair enough, but it's reasonable to go with the simpler solution if you're not given any particular performance requirements.