Reading / Writing files using Sockets

Question

Hi there guys,
I am fairly new to this forum. I have been having a problem for the past three days. I am implementing a client/server implementation using Sockets which is a submodule of a project I am working on. What I want is that a files content are read and transferred over the network to the server that writes it down to a different file .
What the code presently does is :
<<<<Client Code >>>>
It reads a file input.txt and sends the content over the network to the server.
<<<< Server Code >>>
It reads the incoming data from the client and writes the data out to a file called output.txt
What I want now is that the server should read the file output.txt and send the contents to the client which reads it and then writes it down as a new file called serverouput.txt . After that I want to compare and see of the size of input.txt and serveroutput.txt . If both are same that means that data has been written reliably to the server.
I have been trying to implement it for a long time and nothing seems to work out. I am posting the code for both client and server below. Any help in finalising things would be really appreciated.
CLIENT CODE
import java.awt.Color;
import java.awt.BorderLayout;
import java.awt.event.*;
import javax.swing.*;
import java.util.Date;
import java.io.*;
import java.net.*;
class sc {
static final int PORT = 4444;          //Change this to the relevant port
static final String HOST = "127.0.0.1";
     //Change this to the relevant HOST,
//(where Server.java is running)
public static void main(String args[]) {
try {
System.out.print("Sending data...\n");
Socket skt = new Socket(HOST, PORT);
               // Set the socket option just in case server stalls
skt.setSoTimeout ( 2000 );
               skt.setSoKeepAlive(true);
//Create a file input stream and a buffered input stream.
FileInputStream fis = new FileInputStream("input.txt");
BufferedInputStream in = new BufferedInputStream(fis);
BufferedOutputStream out = new BufferedOutputStream( skt.getOutputStream() );
//Read, and write the file to the socket
int i;
while ((i = in.read()) != -1) {
out.write(i);
//System.out.println(i);
               // Enable SO_KEEPALIVE
out.flush();
out.close();
in.close();
skt.close();
catch( Exception e ) {
System.out.print("Error! It didn't work! " + e + "\n");
          catch( IOException e ) {
System.out.print("Error! It didn't work! " + e + "\n");
SERVER CODE
import java.awt.Color;
import java.awt.BorderLayout;
import java.awt.event.*;
import javax.swing.*;
import java.util.Date;
import java.io.*;
import java.net.*;
class ClientWorker implements Runnable {
private Socket client;
ClientWorker(Socket client) {
this.client = client;
public void run(){
try      {
FileOutputStream fos = new FileOutputStream("output.txt");
BufferedOutputStream out = new BufferedOutputStream(fos);
BufferedInputStream in = new BufferedInputStream( client.getInputStream() );
//Read, and write the file to the socket
int i;
while ((i = in.read()) != -1) {
out.write(i);
//System.out.println(i);
System.out.println("Receiving data...");
out.flush();
in.close();
out.close();
client.close();
// srvr.close();
System.out.println("Transfer complete.");
catch(Exception e) {
System.out.print("Error! It didn't work! " + e + "\n");
class ss1 {
ServerSocket server = null;
ss1(){ //Begin Constructor
} //End Constructor
public void listenSocket(){
try{
server = new ServerSocket(4444);
} catch (IOException e) {
System.out.println("Could not listen on port 4444");
System.exit(-1);
while(true){
ClientWorker w;
try{
w = new ClientWorker(server.accept());
Thread t = new Thread(w);
t.start();
} catch (IOException e) {
System.out.println("Accept failed: 4444");
System.exit(-1);
protected void finalize(){
//Objects created in run method are finalized when
//program terminates and thread exits
try{
server.close();
} catch (IOException e) {
System.out.println("Could not close socket");
System.exit(-1);
public static void main(String[] args){
ss1 frame = new ss1();
     frame.listenSocket();
}

Answer 1

............................................. After that I want to
compare and see of the size of input.txt and
serveroutput.txt . If both are same that means that
data has been written reliably to the server.You don't need to do this. TCP/IP ensures the reliable transmition of data. By using a socket you are automaticaly sure that the data is reliably transmitted (Unless there is some sort of exception).
To get the size of the files you can use a File object. Look it up in java.io package in API documentation.
java-code-snippet (without error checking)
File clientFile = new File("input.txt");
clientFile.length();