BufferedReader vs Scanner, and FileInputStream vs FileReader?

Question

Can someone explain to me why can I use FileInputStream or FileReader for a BufferedReader? What's the difference? And at the same time what is the advantage of a Scanner over a BufferedReader? I was reading that it helps by tokenizing, but what does that mean?

Answer 1

Dexter's answer is already useful, but some extra explanation might still help:

In genereal: An InputStream only provides access to byte data from a source. A Reader can be wrapped around a stream and adds proper text encoding, so you can now read chars. A BufferedReader can be wrapped around a Reader to buffer operations, so instead of 1 byte per call, it reads a bunch at once, thereby reducing system calls and improving performance in most cases.

For files:

A FileInputStream is the most basic way to read data from files. If you do not want to handle text encoding on your own, you can wrap it into a InputStreamReader, which can be wrapped into a BufferedReader. Alternatively, you can use a FilerReader, which should basically do the same thing as FileInputStream + InputStreamReader.

Now if you do not want to just read arbitrary text, but specific data types (int, long, double,...) or regular expressions, Scanner is quite useful. But as mentioned, it will add some overhead for building those expressions, so only use it when needed.