java input-output stream files #java #javatutorial #programming

java input-output stream files #java #javatutorial #programming
#javaprogramming MANAGING INPUT/OUTPUT FILES IN JAVA
STREAMS FILES IN JAVA
WE HAVE USED VARIABLES AND ARRAYS FOR SORTING DATA INSIDE THE PROGRAMS.
PROBLEMS:
1- THE DATA IS LOST EITHER WHEN A VARIABLE GOES OUT OF SCOPE OR WHEN THE PORGRAM IS TERMINATED.
2- IT IS A DIFFICULT TO HANDLE LARGE VOULMES OF DATA USING VARIABES AND ARRAYS.
THE DATA IS STORED IN THESE DEVICES USING CONCEPT OF FILES. DATA STORTED IN FILES IS OFTEN CALLED PERSISTENT DATA.
A file is a collection of related records in placed in a particular area on the disk. A records in composed a several fields and filed is a group of charterers.
Storing and managing data using file is known as file processing. Which tasks such as creating files, updating files and manipulation of data.
The process of reading and writing objects is called object serialization.
Concepts of Streams: the flow of data into a program and output means the flow of data out of a program.
Java uses the concept of streams to represent the ordered sequence of data.
A stream presents a uniform, easy-to-use , object oriented interface between the program and the input/output decives .
Keyboard

Java program Screen
Mouse Printer
Memory Memory
Disk Disk
Network Network
Sources : Destination
Relationship of java program with i/o devices

A stream in java is path along which data flows. It has a source of data and destination for that data as depicted


Stream classes : java.io package contains a large number of stream classes that provide processing all types of data.
1- Byte stream classes that provides support for handling I/O operations on bytes.
2- Character stream classes that provide support for managing I/O operations on characters.



Java stream classes
Byte Stream Classes Characters stream classes
Input stream , output stream reader , writer
Memory , file , pipe memory , file , pipe

Byte Stream classes : to provide functional features for creating and manipulating streams and files for reading and writing bytes.
Input stream classes : used to read 8-bit bytes include a super class known as InputStream and a number of subclasses for supporting various input-related functions.
Objects
InputStream
FileInput Stram PipeInput Stream ByteArray Input Stream Sequence input stream Object Input Stream String buffer input stream

FilterInputStream
BufferInputStream PublishedInputStream
DataInputStream
DataInput
(Hierarchy of input stream classes)


The super class InputStream is an abstract class, cannot create instance of this class.
Input functions perform:
1- Reading bytes
2- Closing streams
3- Marking ahead in a stream
4- Finding the number of bytes in a stream.
Read(), read (byte b[]) ,available(), skip(n) , reset(), close()
Output Stream Classes: is an abstract class and therefore we cannot instantiate it. The several subclasses of the outputstream can be used for performing the output operation.
Tasks : writing bytes , closing streams, flushing streams.
Character stream classes: reader and writer stream classes
Reader stream classes : are designed to read character from the fiels. Reader is the base class for all other classes.
The reader class contains methods that are identical to those available in the inputstream class.
Writer stream: designed to perform all output operations on files.
objects
Reader
BufferReader StringReader
CharArrayReader PipeReader
InputStreamReader FilterReader
FileReader PushbackReader
Hierarchy of reader stream classes
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FileNotFoundException :
InperruptedIOException:
IOException
Creating of files :
- Name of a file
- Data type to be stored
- Purpose (reading , writing or updating)
- Method of creating the file