(receiver side) Java Program to implement Stop and Wait Protocol while sending a message travelling from sender to receiver (CN)

/*Aim: A Java Program implementing Stop and Wait Protocol while sending a message travelling from sender to receiver. */
/*For complete explanation visit: Prof. Brinda's Blog*/
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class Reciever{
ServerSocket reciever;
Socket connection=null;
ObjectOutputStream out;
ObjectInputStream in;
String packet,ack,data="";
int i=0,sequence=0;
Reciever()
{
}
public void run(){
try{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
reciever = new ServerSocket(2009,10);
System.out.println("waiting for connection...");
connection=reciever.accept();
sequence=0;
System.out.println("Connection established :");
out=new ObjectOutputStream(connection.getOutputStream());
out.flush();
in=new ObjectInputStream(connection.getInputStream());
out.writeObject("connected .");
do{
try{
packet=(String)in.readObject();
if(Integer.valueOf(packet.substring(0,1))==sequence){
data+=packet.substring(1);
sequence=(sequence==0)?1:0;
System.out.println("\n\nreceiver >"+packet);
}
else
{
System.out.println("\n\nreceiver >"+packet +" duplicate data");
}
if(i<3){
out.writeObject(String.valueOf(sequence));i++;
}
else{
out.writeObject(String.valueOf((sequence+1)%2));
i=0;
}
}
catch(Exception e){}
}while(!packet.equals("end"));
System.out.println("Data recived="+data);
out.writeObject("connection ended .");
}
catch(Exception e){}
finally{
try{
in.close();
out.close();
reciever.close();
}
catch(Exception e){}
}
}
public static void main(String args[]){
Reciever s=new Reciever();
while(true){
s.run();
}
}
}