Hi Friend,

Try the following code:

import java.io.*;
import java.util.*;
class Directory implements Comparable{
int id;
String name;
String address;
int phoneNo;

public int getId(){
return id;
}
public void setId(int id){
this.id=id;
}

public String getName(){
return name;
}
public void setName(String name){
this.name=name;
}
public String getAddress(){
return address;
}
public void setAddress(String address){
this.address=address;
}
public int getPhoneNo(){
return phoneNo;
}
public void setPhoneNo(int phoneNo){
this.phoneNo=phoneNo;
}

public int compareTo(Object ob) throws ClassCastException {
if (!(ob instanceof Directory))
throw new ClassCastException("Error");
int ide = ((Directory) ob).getId();
return this.id - ide;
}
}
public class TelephoneDirectory{

public static void main(String[] args) throws Exception{
Scanner scan = new Scanner(System.in);
int menu = 0;
System.out.println("Telephone Directory Management System");
System.out.println();
System.out.println("1. Accept Data");
System.out.println("2. Search");
System.out.println("3. Sort Data");
System.out.println("4. List of all persons");
System.out.println("5. Exit");
boolean quit = false;
do{
System.out.print("Please enter your choice: ");
menu = scan.nextInt();
System.out.println();

switch(menu){
case 1:
System.out.print("Enter student ID: ");
int ID = scan.nextInt();
System.out.print("Enter Name: ");
String name= scan.next();
System.out.print("Enter Address: ");
String address=scan.next();
System.out.println("Enter Phone No: ");
int no=scan.nextInt();
FileWriter fw = new FileWriter(new File("directory.txt"),true);
BufferedWriter out = new BufferedWriter(fw);
out.write(ID+" "+name+" "+address+" "+no);
out.newLine();
out.close();
break;
case 2:
System.out.print("Enter name to search information: ");
String n=scan.next();
File f = new File("directory.txt");
try {
BufferedReader freader = new BufferedReader(new FileReader(f));
String s;
while ((s = freader.readLine()) != null) {
String[] st = s.split(" ");
String id = st[0];
String nm = st[1];
String add = st[2];
String phoneNo = st[3];
if (n.equals(nm)) {
System.out.println("***********Information**************");
System.out.println("Address : "+add);
System.out.println("PhoneNo : "+phoneNo);
}
}
freader.close();
} catch (Exception e) {
}
break;

continue.........

case 3:
File file = new File("directory.txt");
FileInputStream fstream = new FileInputStream(file);
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader( new InputStreamReader(in));
String strLine;
ArrayList list = new ArrayList();
while ((strLine = br.readLine()) != null) {
list.add(strLine);
}
int j = 0;
Directory data[] = new Directory[list.size()];
try {
Iterator itr;
for (itr = list.iterator(); itr.hasNext();) {
String str = itr.next().toString();
String[] splitSt = str.split(" ");
String id = "", nn = "", add = "", pno = "";
for (int i = 0; i < splitSt.length; i++) {
id = splitSt[0];
nn = splitSt[1];
add = splitSt[2];
pno = splitSt[3];

}
data[j] = new Directory();
data[j].setId(Integer.parseInt(id));
data[j].setName(nn);
data[j].setAddress(add);
data[j].setPhoneNo(Integer.parseInt(pno));

j++;
}

BufferedWriter bw = new BufferedWriter(new FileWriter(file,true));
Arrays.sort(data);
System.out.println("********Sorted by id********");
String strVal = "";
for (int i = 0; i < 8; i++) {
Directory show = data[i];
int ide = show.getId();
String nnn = show.getName();
String add = show.getAddress();
int phone = show.getPhoneNo();
System.out.println(ide+" "+nnn+" "+add+" "+phone);
}
} catch (Exception e) {
}
break;

case 4:

FileInputStream fis = new FileInputStream( new File("directory.txt"));
DataInputStream dis = new DataInputStream(fis);
BufferedReader reader = new BufferedReader( new InputStreamReader(dis));
String st;
ArrayList al = new ArrayList();
while ((st = reader.readLine()) != null) {
al.add(st);
}
Iterator itr;
for (itr=al.iterator(); itr.hasNext(); ){
String str=itr.next().toString();
String [] splitSt =str.split(" ");
String id="",na="",ada="",ph="";
for (int i = 0 ; i < splitSt.length ; i++) {
id=splitSt[0];
na=splitSt[1];
ada=splitSt[2];
ph=splitSt[3];
}
System.out.println(id+" "+na+" "+ada+" "+ph);
}
break;
case 5:
quit = true;
break;
default:
System.out.println("Invalid Entry!");
}
}
while (!quit);
}
}

Thanks