tailieunhanh - Lecture Java™ How to Program (8/e) - Chapter 17: Files, streams and object serialization
After completing this unit, you should be able to: To create, read, write and update files; to use class File to retrieve information about files and directories; the Java input/output stream class hierarchy; the differences between text files and binary files; sequential-access and random-access file processing; to use classes Scanner and Formatter to process text files;. | Java How to Program, 8/e (C) 2010 Pearson Education, Inc. All rights reserved. (C) 2010 Pearson Education, Inc. All rights reserved. (C) 2010 Pearson Education, Inc. All rights reserved. Data stored in variables and arrays is temporary It’s lost when a local variable goes out of scope or when the program terminates For long-term retention of data, computers use files. Computers store files on secondary storage devices hard disks, optical disks, flash drives and magnetic tapes. Data maintained in files is persistent data because it exists beyond the duration of program execution. (C) 2010 Pearson Education, Inc. All rights reserved. Ultimately, a computer processes data items as combinations of zeros and ones It’s simple and economical for engineers to build electronic devices that can assume two stable states—one representing 0 and the other representing 1. The smallest data item in a computer can assume the value 0 or the value 1. Such a data item is called a bit . | Java How to Program, 8/e (C) 2010 Pearson Education, Inc. All rights reserved. (C) 2010 Pearson Education, Inc. All rights reserved. (C) 2010 Pearson Education, Inc. All rights reserved. Data stored in variables and arrays is temporary It’s lost when a local variable goes out of scope or when the program terminates For long-term retention of data, computers use files. Computers store files on secondary storage devices hard disks, optical disks, flash drives and magnetic tapes. Data maintained in files is persistent data because it exists beyond the duration of program execution. (C) 2010 Pearson Education, Inc. All rights reserved. Ultimately, a computer processes data items as combinations of zeros and ones It’s simple and economical for engineers to build electronic devices that can assume two stable states—one representing 0 and the other representing 1. The smallest data item in a computer can assume the value 0 or the value 1. Such a data item is called a bit Short for “binary digit”—a digit that can assume one of two values. (C) 2010 Pearson Education, Inc. All rights reserved. Programmers prefer to work with decimal digits (0–9), letters (A–Z and a–z), and special symbols (., $, @, %, &, *, (, ), –, +, ", :, ? and / ). Known as characters. Character set—the set of all the characters used to write programs and represent data items. Java uses Unicode characters that are composed of two bytes, each composed of eight bits Java type byte can be used to represent byte data. Unicode contains characters for many of the world’s languages. (C) 2010 Pearson Education, Inc. All rights reserved. Fields are composed of characters or bytes. A field is a group of characters or bytes that conveys meaning. Data items processed by computers form a data hierarchy that becomes larger and more complex in structure as we progress from bits to characters to fields, and so on. (C) 2010 Pearson Education, Inc. All rights reserved. Typically, several .
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