Create an application which transfer file form server to client using UDP in JAVA

Server.java

package filetransfr;

import java.io.*;

import java.net.*;

public class Filetransfr {   

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

        boolean flg;

        byte data[]=new byte[100];

        System.out.println("Server is Ready...");

        int cprt=777,sprt=888;

        InetAddress xn= InetAddress.getLocalHost();

        DatagramPacket dp=new DatagramPacket(data, data.length, xn, sprt);

        DatagramSocket ds=new DatagramSocket(cprt);

        ds.receive(dp);      

        ds.close();

        String fname=new String(dp.getData(),0,dp.getLength());

        System.out.println("Received File Name From Client : " + fname);

        File f=new File(fname);

        if(f.exists()) flg=true;

        else flg=false;

        String dt;

        if(flg==true)

            dt="yes";

        else

            dt="no";

        System.out.println("File Found : " + dt);

        data=dt.getBytes();

        dp=new DatagramPacket(data, data.length, xn, sprt);

        ds=new DatagramSocket(cprt);

        ds.send(dp);

        System.out.println("File Found Status Send To Client...");

        ds.close();

        if(flg==true){

            FileReader rd=new FileReader(f);

            BufferedReader br=new BufferedReader(rd);

            String str=null;

            System.out.println("Send File Data To Client ...");

            while((str=br.readLine())!=null){

                ds=new DatagramSocket(cprt);

                data=str.getBytes();

                dp=new DatagramPacket(data, data.length, xn, sprt);               

                ds.send(dp);

                ds.close();

            }           

        }

        else{

            System.out.println("File Found : " + dt);

        }       

      }

}

Client.java

package filetransfr;

import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

import java.net.Socket;

public class clnt   {

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

        BufferedReader br=new BufferedReader(new InputStreamReader(System.in) );

        System.out.print("Enter FileName : ");

        String fnm=br.readLine();       

        byte data[]=new byte[100];

        int cprt=777,sprt=888;

        InetAddress xn= InetAddress.getLocalHost();       

        data=fnm.getBytes();

        DatagramPacket dp=new DatagramPacket(data, data.length, xn, cprt);

        DatagramSocket ds=new DatagramSocket(sprt);

        ds.send(dp);

        System.out.println("Send File Name To Server...");

        ds.close();       

        dp=new DatagramPacket(data, data.length, xn, cprt);

        ds=new DatagramSocket(sprt);

        ds.receive(dp);

        String s=new String(dp.getData(),0,dp.getLength());

        System.out.println("Received File Found Status ...");

        System.out.println("File Found : " + s);       

        System.out.println("Received File Data From Server....");

        System.out.println("File Data Are :");

        while(true)

        {

            ds.receive(dp);

            s=new String(dp.getData(),0,dp.getLength());

            if(s==null)

            {

                break;

            }

            System.out.println(s);

        }       

    }   

}