如何获得有关Java流的完整图片？

Question

Whenever I have to work with topics like file-handling or socket-programming, I have to look for sample code on the internet to see how the xxStreamxx,xxReader,xxWriter classes are used. I want to be able to use them on my own and know how they work.

How do I go about learning that?

Answer 1

The main idea is simple.

Streams are for binary read/write. Readers/Writers are for character read/write (in Java byte is not a char, since char is unicode). If it is possible to convert binary stream into character sequence, there is an appropriate reader for a stream.

For example, FileInputStream extends InputStream is ty read file binary. If this is textual file to read, you wrap this object into InputStreamReader extends Reader providing character set. Now you are able to read characters.

If you want to do readLine() you need to wrap this reader into BufferedReader .

Similarly with writers.

So, the idea is wrapping to get new abilities.

Answer 2

In this website you could find a variety of examples on how to write your own streams in Java: http://java.sun.com/developer/technicalArticles/Streams/WritingIOSC/

Just looking at the examples sometimes helps you much more than the explanations...

Please scroll to the middle and bottom of the page.

Answer 3

First of all, you have to learn and understand what streams are. If you don't understand the concepts behind them, you will be always copying code. So read the "Basic I/O lesson of the java tutorial": http://docs.oracle.com/javase/tutorial/essential/io/streams.html . A comprehensive presentation about this topic is this one from javapassion.com: http://www.javapassion.com/javase/javaiostream.pdf .

While reading, as I usually told my students: "write code and make mistakes" :-)