The File IO

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First program to understand FileInputStream class -: 

import java.io.FileInputStream;

public class DemoOfFileInputStreamPartOne
{
public static void main(String[] args)
{
try
{
  // create object of scanner to get input from keyboard

   Scanner sc = new Scanner(System.in);

   System.out.print("Enter a the name of file with path to open in read mode: ");

String filepath = sc.nextLine();

// open this file in read mode
FileInputStream fi = new FileInputStream
(filepath);

// start an inifinite loop
while(true)
{
// fetch a byte from file and store it
int var = fi.read();

// check for end of the data
if(var == -1)
{
break; // go out of loop
}

// convert the byte into the ASCII char and store
char ch = (char)var;

System.out.print(ch);
}

// close the file
fi.close();

}
catch(Exception e)
{
System.out.println("error "+e);
}
}
}

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Second program to understand FileInputStream class -: 

import java.io.FileInputStream;

public class DemoOfFileInputStreamPartTwo 

{

public static void main(String[] args) 

{

try

{

  // create object of scanner to get input from keyboard

   Scanner sc = new Scanner(System.in);

   System.out.print("Enter a the name of file with path to open in read mode: ");

String filepath = sc.nextLine();

// open this file in read mode

FileInputStream fi = new FileInputStream(filepath);

// get no of bytes those can be read by the read() method

int size = fi.available();

// create an array of byte to store the data of file

byte[] array = new byte[size];

// fetch file data and store it inside this array

fi.read(array);

// convert array of byte into string

String str = new String(array);

System.out.println(str);

// close the file

fi.close();

}

catch(Exception e)

{

System.out.println("error "+e);

}

}

}

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First program to understand FileOutputStream class -: 

import java.io.FileOutputStream;

public class DemoOfFileOutputStreamPartOne 

{

public static void main(String[] args) 

{

try 

{

  // create object of scanner to get input from keyboard

   Scanner sc = new Scanner(System.in);

   System.out.print("Enter a the name of file with path to open in write mode: ");

String filepath1 = sc.nextLine();

   System.out.print("Enter a the name of file with path to open in append mode: ");

String filepath2 = sc.nextLine();

// open a file in write mode

FileOutputStream fo1 = new FileOutputStream(filepath1,false);

// open a file in append mode

FileOutputStream fo2 = new FileOutputStream

(filepath2,true);

System.out.println("files has been created");

  // close the files
fo1.close();
fo2.close();

} 

catch (Exception e) 

{

System.out.println("error "+e);

}

}

}

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Second program to understand FileOutputStream class -: 

import java.io.FileOutputStream;

public class DemoOfFileOutputStreamPartTwo

{

public static void main(String[] args) 

{

try 

{

  // create object of scanner to get input from keyboard

   Scanner sc = new Scanner(System.in);

   System.out.print("Enter a the name of file with path to open in write mode: ");

String filepath = sc.nextLine();

   System.out.print("Enter the data to be stored inside the file: ");

String filedata = sc.nextLine();

// open a file in write mode

FileOutputStream fo = new FileOutputStream

(filepath,false);

// convert string into array of byte and store 

byte[] array = text.getBytes();

// fetch the data of array using for loop

for (int i = 0; i < array.length; i++) 

{

// store the data of ith element of array inside file

fo.write(array[i]);

}

// close the file

fo.close();

} 

catch (Exception e) 

{

System.out.println("error "+e);

}

}

}

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Third program to understand FileOutputStream class -: 

import java.io.FileOutputStream;

public class DemoOfFileOutputStreamPartThree

{

public static void main(String[] args) 

{

try 

{

   // create object of scanner to get input from keyboard
   Scanner sc = new Scanner(System.in);

   System.out.print("Enter a the name of file with path to open in read mode: ");

String filepath = sc.nextLine();

// open  file in write mode

FileOutputStream fo = new FileOutputStream(filepath,false);

// convert string into array of byte and store 

byte[] array = text.getBytes();

// store the data of file inside the array in one go (matlab ek baar mai)

fo.write(array);

// close the file

fo.close();

} 

catch (Exception e) 

{

System.out.println("error "+e);

}

}

}

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