1. 8/30/2018
CPRG 215 Introduction to Object-Oriented Programming with Java Module 5- The java.io Package Topic 5.1 Input and Output Streams, Readers and Writers
Produced by Harvey Peters, 2008
Copyright SAIT

2. Please read the following sections
in your textbook
Core Java, Volume II–Advanced Features, Eighth Edition
By Cay S. Horstmann & Gary Cornell
Chapter 1 - Streams and Files
Streams
CPRG 215 Module 5.1- Input and Output Streams, Readers and Writers
Copyright SAIT

3. java.io Designed for maximum flexibility
Numerous classes for specific types of data
Handles 8-bit and 16-bit formats to accommodate binary, ASCII and Unicode data
Can connect to
Keyboard/console
Standard Input (STDIN)
Standard Output (STDOUT)
Standard Error (STDERR)
Files
Processes
Network sockets
CPRG 215 Module 5.1- Input and Output Streams, Readers and Writers
Copyright SAIT
Topic 5.1.1

4. java.io
Based on the metaphor of streams of data flowing in and out of a program
InputStream and OutputStream are basic classes
Build advanced handling by joining objects together
CPRG 215 Module 5.1- Input and Output Streams, Readers and Writers
Copyright SAIT
Topic 5.1.1

5. Input
Calling System.in returns an InputStream that is connected to the keyboard
This InputStream can be used as a constructor argument to create other streams
Each stream has read methods
Read at whatever point is needed
CPRG 215 Module 5.1- Input and Output Streams, Readers and Writers
Copyright SAIT
Topic 5.1.2

6. Output Don’t forget to flush the buffer!
Output can go to various destinations
For files, attach a FileOutputStream to a file
To improve efficiency of writing attach a buffer
Write to the buffer, data flows through the other objects to the file
Don’t forget to flush the buffer!
CPRG 215 Module 5.1- Input and Output Streams, Readers and Writers
Copyright SAIT
Topic 5.1.3

7. Input Stream Methods The three basic read() methods The other methods
int read()
int read(byte[])
int read(byte[], int, int)
The other methods
void close()
int available()
skip(long)
boolean markSupported()
void mark(int)
void reset(int)
CPRG 215 Module 5.1- Input and Output Streams, Readers and Writers
Copyright SAIT
Topic 5.1.4

8. Output Stream Methods The three basic write() methods
void write(int)
void write(byte[])
void write(byte[], int, int)
The other methods
void close()
void flush()
CPRG 215 Module 5.1- Input and Output Streams, Readers and Writers
Copyright SAIT
Topic 5.1.5

9. Readers and Writers Java is based on Unicode characters - 16 bits
Most hardware is 8-bit
InputStreams & OutputStreams are 8-bit
Read and write bytes
Readers & Writers provided to handle 16-bit data
Read and Write chars
Files can connect to streams or readers & writers
Automatic conversion between 16 and 8 bit
CPRG 215 Module 5.1- Input and Output Streams, Readers and Writers
Copyright SAIT
Topic 5.1.6