Java Quick Reference - java.io Package

Language Fundamentals

Operators and Assignments

Flow Control and Exceptions

Declarations and Access Control

Garbage Collection

Overloading and Overriding

Threads

The java.lang Package

The java.util Package

The java.awt Package

The java.io Package

References

Miscellaneous Notes

Tips & Traps

Mock Exams

The java.io Package - Overview

the package contains three main groups of classes and interfaces
1. classes to build data streams
2. classes and interfaces for serialization
3. classes and interfaces for working with the file system

Data Streams (JCL1)

data streams that read values from a data source are input streams
data streams that write values to a data repository are output streams
the data can be either byte or character values

DataStream SuperClasses
Byte Streams	Character Streams
abstract class InputStream	abstract class Reader
abstract class OutputStream	abstract class Writer

there are two classes which convert bytes to characters

    class InputStreamReader extends Reader
    class OutputStreamWriter extends Writer

data containers, for example files, usually provide methods which return a stream for either reading or writing
data streams can be chained together

Filter Streams

filter streams perform some processing or filtering as the data is passed through
a filter ouput stream performs the processing before the data is written out
a filter input stream performs the processing after the data is read from its original source

FilterStream SuperClasses
Byte Streams	Character Streams
class FilterInputStream	class FilterReader
class FilterOutputStream	class FilterWriter

there are number of filter streams for both byte streams

    BufferedInputStream                 BufferedOutputStream
    DataInputStream                     DataOutputStream
    LineNumberInputStream               PrintStream
    PushbackInputStream

and character streams

    BufferedReader                      PrintWriter
    LineNumberReader
    PushbackReader

In-Memory Streams

there are also classes for reading and writing data held in memory

    ByteArrayInputStream                CharArrayReader
    ByteArrayOutputStream               CharArrayWriter
                                        StringReader     
                                        StringWriter

the StringReader/Writer classes read data from a StringBuffer object

Pipes

there are classes that allow you to build streams that operate between threads

    PipedInputStream                    PipedReader
    PipedOutputStream                   PipedWriter

Files

there are a number of classes for working with the file system

    File                                
    FileDescriptor                      
    
    FileInputStream                     FileReader
    FileOutputStream                    FileWriter
    FilenameFilter
    FilePermission                      RandomAccessFile

note that File, FileDescriptor and RandomAccessFile are direct subclasses of Object

Note

The File class can be used to create directories

Serialization (JCL1)

serialization is the process of converting an object to a stream of bytes in such a manner that the original object can be rebuilt (lets you write an object to a file or other data container)

	Pkg Overview	Data Streams	Character Streams	Byte Streams	File Class	Readers & Writers
	Filter Streams	Data Input/Output	Reading & Writing Files	Serialization