December 2009
Intermediate to advanced
1170 pages
28h 4m
English
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Chapter 19. Streams and Binary Input/Output
CHAPTER GOALS
To become familiar with the concepts of text and binary formats
To learn about encryption
To understand when to use sequential and random file access
To be able to read and write objects using serialization
In this chapter you will learn more about how to write Java programs that interact with disk files and other sources of bytes and characters. You will learn about text and binary formats, and about sequential and random access to the data in a file. We will discuss how you can use object serialization to save and load complex objects with very little effort. As an application of file processing, you will study a program for encrypting and decrypting sensitive data.
Readers, Writers, and Streams
There are two fundamentally different ways to store data: in text format or binaryformat. In text format, data items are represented in human-readable form, as a sequence of characters. For example, in text form, the integer 12,345 is stored as the sequence of five characters:
'1' '2' '3' '4' '5'
In binary form, data items are represented in bytes. A byte is composed of 8 bitsand can denote one of 256 values. For example, in binary format, the integer 12,345 is stored as a sequence of four bytes:
0 0 48 57(because 12,345 = 48 • 256 + 57).
The Java library provides two sets of classes for handling input and output. Streams handle binary data. Readers and writers handle data in text form. Figure 1 shows a part of the hierarchy of the Java classes ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.