Module# 12: Java IO Streams and File Lecture#43: IO with Byte Streams

// Example 43.1: Reading String, Integer and Double from Keyboard

import java.io.*;

public class KeyboardReading{

public static void main(String args[]) throws IOException {

DataInputStream dis = new DataInputStream(System.in);

System.out.println("Enter a String: ");

String str1 = dis.readLine();

System.out.println("Entered String value is: " + str1);

System.out.println("Enter a whole number: ");

String str2 = dis.readLine();

int x = Integer.parseInt(str2);

System.out.println("Enter a double value: ");

String str3 = dis.readLine();

double y = Double.parseDouble(str3);

if(x > y)

System.out.println("First number " +x + " is greater than second number " + y);

else

System.out.println("First number " +x + " is less than second number " + y);

dis.close();

}

}

// Example 43.2: Calculator using DataInputStream

import java.io.*;

class InterestCalculator {

public static void main(String args[ ] ) {

Float principalAmount = new Float(0);

Float rateOfInterest = new Float(0);

int numberOfYears = 0;

DataInputStream in = new DataInputStream(System.in);

String tempString;

System.out.print("Enter Principal Amount: ");

System.out.flush();

tempString = in.readLine();

principalAmount = Float.valueOf(tempString);

System.out.print("Enter Rate of Interest: ");

System.out.flush();

tempString = in.readLine();

rateOfInterest = Float.valueOf(tempString);

System.out.print("Enter Number of Years:");

System.out.flush();

tempString = in.readLine();

numberOfYears = Integer.parseInt(tempString);

// Input is over: calculate the interest

int interestTotal = principalAmount*rateOfInterest*numberOfYears;

System.out.println("Total Interest = " + interestTotal);

}

}

// Example 43.3: Reading bytes from a file and display data

// Read the file address from the Command Line

import java.io.*;

class ReadBytesDemo {

public static void main (String args[]) {

FileInputStream infile = null; // Create an input file stream

int b;

try {

infile = new FileInputStream(args[0]);

// Connect infile stream to the required file

while((b = infile.read()) != -1) {

System.out.print((char)b); // Read and display data

}

infile.close();

}

catch(IOException ioe) {

System.out.println(ioe);

}

}

}

class InputStreamTest {

public static void main (String args [ ] ) {

int size;

// To open a file input stream.

FileInputStream fin;

fin = new FileInputStream (" C:\WINDOWS\SYSTEM\SYSTEM.INI");

size = fin.available( );

// returns the number of bytes available

System.out.println("Total bytes ::" + size);

System.out.println ( " First ¼ is displayed : Using read( )");

for (int i = 0; i < size /4 ; i++ ) {

System.out.println ((char) fin.read( ) );

}

// Example 43.4: Reading a file using FileInputStream

class InputStreamTest {

public static void main (String args [ ] ) {

int size;

// To open a file input stream.

FileInputStream fin;

fin = new FileInputStream (" C:\WINDOWS\SYSTEM\SYSTEM.INI");

size = fin.available( );

// returns the number of bytes available

System.out.println("Total bytes ::" + size);

System.out.println ( " First ¼ is displayed : Using read( )");

for (int i = 0; i < size /4 ; i++ ) {

System.out.println ((char) fin.read( ) );

}

System.out.println (" Remaining bytes :" + fin.available( ) );

System.out.println ("Next ¼ is displayed : Using read( b[ ])");

byte b[] = new byte[size/4];

if (fin.read (b) != b.length )

System.err.println ("File reading error : ");

else {

String temp = new String (b, 0, 0, b.length );

// Convert the bytes into string

System.out.println (temp) ;

// display text string.

System.out.println (" Still available:"+fin.available( ) );

System.out.println (" skipping ¼ : Using skip ( )" );

fin.skip(size/4);

System.out.println (" File remaining for read ::"+fin.available( ) );

}

fin.close ( ); // Close the input stream

}

}