FILE IO IN JAVA AND ITS DETAIL DESCRIPTION, Thesis of Java Programming

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Streams and Input/Output Files

Part I

Chapter- 07

Mohammed Husain Bohara

Streams & Files

The objectives of this chapter are:

To understand the principles of I/O

streams and where to use them

To understand the options and limitations

of I/O streams

To become comfortable with the

mechanisms for accessing the file system

Limitation

 The data is lost when variable goes out of

scope or when the program terminates.

That is data is stored in temporary/mail

memory is released when program

terminates.

 It is difficult to handle large volumes of

data.

Solution

 We can overcome this problem by storing

data on secondary storage devices such

as floppy or hard disks.

 The data is stored in these devices using

the concept of Files and such data is

often called persistent data.

C Input/Output Revision

FILE* fp;

fp = fopen(“In.file”, “rw”);

fscanf(fp, ……);

frpintf(fp, …..);

fread(………, fp);

fwrite(……….., fp);

Java Application Requirement

abc.txt Java Application xyz.txt

FIS

read

FOS

write

Will it Compile or not

javap java.io.FileInputStream

Output

 Data will be copied successfully

What will be the output here?

import java.io.*;

class FileIOExample

{

public static void main(String[] args) throws FileNotFoundException, IOException { FileInputStream fis = new FileInputStream("abc.txt"); FileOutputStream fos = new FileOutputStream("xyz.txt"); int c; while((c=fis.read())!=-1) { System.out.println(c); fos.write(c); } fis.close(); fos.close(); }

}

I/O and Data Movement

 The flow of data into a program

(input) may come from different

devices such as keyboard,

mouse, memory, disk, network,

or another program.

 The flow of data out of a

program (output) may go to the

screen, printer, memory, disk,

network, another program.

 Both input and output share a

certain common property such as

unidirectional movement of data

• a sequence of bytes and

characters and support to the

sequential access to the data.

Streams

 Java Uses the concept of

Streams to represent the

ordered sequence of data, a

common characteristic shared

by all I/O devices.

 Streams presents a uniform,

easy to use, object oriented

interface between the

program and I/O devices.

 A stream in Java is a path

along which data flows (like a

river or pipe along which

water flows).

Java Stream Classes

 Input/Output related classes are defined in

java.io package.

 Input/Output in Java is defined in terms of

streams.

 A stream is a sequence of data, of no

particular length.

 Java classes can be categorised into two

groups based on the data type one which

they operate:

 Byte streams

 Character Streams

Streams

Byte Streams Character streams

Operated on 8 bit (

byte) data.

Operates on 16-bit

(2 byte) unicode

characters.

Input

streams/Output

streams

Readers/ Writers