Why are you using the title "Console" for your class? There already is a Console class, so that is a potential course of confusion.
Why are you using input streams for text files, rather than BufferedReader and FileReader? FileInputStream and BufferedInputStream are not intended for text files.
Why are you using StringBuffer in a non-synchonised environment;
you should be using StringBuilder.
If you use the methods which allow you to read a line, you can simply check the length of the line; it is returned as a
String, so it has a method for finding its length. Remember a blank line would have length 0, whereas a line filled with spaces will have a greater length.
Simply seeking the new line (correctly called line-feed) character may be unreliable, since different operating systems use different combinations of characters to delimit the lines. If you do in fact find a line-feed character, that might mean you have reached the end of a line, rather than your having an empty line.