File Handling program using Java

import java.io.*;
import java.util.*;
class record implements Serializable
{
static Scanner input=new Scanner(System.in);
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
int roll;
String name;

void insert()
{
try
{
System.out.println(“\n Enter Roll No:: “);
roll=input.nextInt();
System.out.println(“\n Enetr Name:: “);
name=br.readLine();
FileOutputStream fout=new FileOutputStream(“Student.txt”,true);
byte buff[]=name.getBytes();
fout.write((char)roll);
fout.write(‘\n’);
fout.write(buff);
fout.write(‘\n’);
fout.close();
}
catch(Exception e)
{
System.out.println(e.getMessage());
}
}
void delete(int r)
{
try
{
FileInputStream fin = new FileInputStream(“student.txt”);
FileOutputStream fout=new FileOutputStream(“temp.txt”);

while(true)
{
int a=fin.read();
if(a==-1)
break;
if(a!=r)
{
fout.write((byte)a);
a=fin.read();
fout.write(a);
while(true)
{
a=fin.read();
if(a==’\n’)
break;
fout.write(a);
}
fout.write(a);
}
else
{
a=fin.read();
do{
a=fin.read();
}while(a!=’\n’);
}
}
fin.close();
fout.close();
File f=new File(“student.txt”);
File f1=new File(“temp.txt”);
if(f.delete())
f1.renameTo(new File(“student.txt”));
else
System.out.println(“Error”);

}
catch(Exception e)
{
System.out.println(e.getMessage());
}
}
void showdata(int r)
{
try
{
FileInputStream fin=new FileInputStream(“student.txt”);
while(true)
{

int a=fin.read();
if(a==-1)
break;
if(a==r)
{
System.out.println(“roll no:: “+a);
a=fin.read();
System.out.println(“Name:: “);
do
{
a=fin.read();
System.out.print((char)a);
}while(a!=’\n’);
}
else
{
do
{
a=fin.read();
}while(a!=’\n’);
}

}

}
catch(Exception e)
{
System.out.println(e.getMessage());
}
}

void show()
{
try
{

FileInputStream fin=new FileInputStream(“student.txt”);
while(true)
{
int a=fin.read();
if(a==-1)
break;
System.out.println(“roll no:: “+a);
a=fin.read();
System.out.println(“Name:: “);
do
{
a=fin.read();
System.out.print((char)a);
}while(a!=’\n’);

}

}
catch(Exception e)
{
System.out.println(e.getMessage());
}
}
}

public class Student extends record
{
public static void main(String args[])
{
try
{
while(true){
System.out.println(“\nEnter your choice : “);
System.out.println(“1:Insert.”);
System.out.println(“2:Delete.”);
System.out.println(“3:View record.”);
System.out.println(“4:View All.\n”);
int choice=input.nextInt();
record r=new record();
switch(choice)
{
case 1:
r.insert();
break;
case 2:
System.out.println(“Enter roll no. : “);
int roll=input.nextInt();
r.delete(roll);
break;
case 3:
System.out.println(“Enter roll no. : “);
roll=input.nextInt();
r.showdata(roll);
break;
case 4:
r.show();
break;
default:
System.out.println(“Invalid Entry !!”);
break;
}
}
}
catch(Exception e)
{
System.out.println(e.getMessage());
}
}
}