Replaced use of DataInputStream with BufferedReader for console input

Using the readLine() method with DataInputStream is deprecated because of some improper conversion of bytes. I performed the recommended replacement, as seen in the Java documentation, of making it use a BufferedReader instead.

I also made it a class-wide static variable which is initialized in the main(...) function, so that it is available for input across all functions in the class, rather than declaring a new stream in every function that needs input.