ReceiverMain.java

import java.net.*; import java.io.*; class RequesterMain {

ObjectOutputStream out;
ObjectInputStream in;
Socket connection=null;
String message,message1;
RequesterMain(){}
void run()
{
    try
    {


        connection=new Socket("localhost",19999);
        InputStreamReader isr=new InputStreamReader(System.in);
        BufferedReader stdin=new BufferedReader(isr);
        out=new ObjectOutputStream(connection.getOutputStream());
        in=new ObjectInputStream(connection.getInputStream());
        System.out.println("connected to port"+connection.getLocalPort());
        try
        {
        message=(String)in.readObject();
        System.out.println(message);
        }
        catch(ClassNotFoundException e)
        {
            System.out.println("Exception is"+e);
        }
        message="";
        System.out.println("Enter the  number :");
        message1=stdin.readLine();
        out.writeObject(message1);
        out.flush();

        try
        {
        message=(String)in.readObject();
        System.out.println(message);
        }
        catch(ClassNotFoundException e)
        {
            System.out.println("Exception is"+e);
        }
        System.out.println(" The binary  form of  number is:"+message);

    }
    catch(UnknownHostException ae)
    {
        System.out.println("Exception is"+ae);
    }
    catch(IOException e)
    {
        System.out.println("Exception is"+e);
    }
    try
    {
    out.close();
        in.close();
        connection.close();
    }
    catch(IOException e)
    {
        System.out.println("Exception is"+e);
    }

}


public  static void main(String args[])throws IOException
{
    RequesterMain s=new RequesterMain();
    s.run();
}

}

ServerMain.java

import java.net.*; import java.io.*; class ServerMain {

ServerSocket server;
ObjectOutputStream out;
ObjectInputStream in;
Socket connection1=null;
String message,message1,message2="";
int i=7;
ServerMain(){}
void run()
{
    try
    {
        System.out.println("waiting  for  connection");
        message="hi  i  am server";
        server=new ServerSocket(19999,10);

        connection1=server.accept();
        System.out.println("connected to port"+connection1.getLocalPort());
        out=new ObjectOutputStream(connection1.getOutputStream());
        in=new ObjectInputStream(connection1.getInputStream());
        out.writeObject(message);
        out.flush();
        try
        {
        message1=(String)in.readObject();
        System.out.println(message1);
        }
        catch(ClassNotFoundException e)
        {
            System.out.println("Exception is"+e);
        }
        int m;
        int n=Integer.parseInt(message1);
        message1="";
        while(n>0)
        {
         m=n%2;
             message1=message1+m;
         n=n/2;

         i--;
        }
        System.out.println(message1);
         n=message1.length();
        System.out.println("string in reversed order is ");
        for(int i=n-1;i>=0;i--)
        {
        char c=message1.charAt(i);
        message2+=c;
        }

        out.writeObject(message2);
        out.flush();            

    }
    catch(UnknownHostException ae){
        System.out.println("Exception is"+ae);
    }
    catch(IOException e)
    {
        System.out.println("Exception is"+e);
    }
    try
    {
    out.close();
        in.close();
        connection1.close();
    }
    catch(IOException e)
    {
        System.out.println("Exception is"+e);
    }   }



public  static void main(String args[])throws IOException
{
    ServerMain s=new ServerMain();
    s.run();
}

}

run first ServerMain in one cmd and ReceiverMain.java in another cmd.

ReceiverMain.java

import java.net.*; import java.io.*; class RequesterMain {

ObjectOutputStream out;
ObjectInputStream in;
Socket connection=null;
String message,message1;
RequesterMain(){}
void run()
{
    try
    {


        connection=new Socket("localhost",19999);
        InputStreamReader isr=new InputStreamReader(System.in);
        BufferedReader stdin=new BufferedReader(isr);
        out=new ObjectOutputStream(connection.getOutputStream());
        in=new ObjectInputStream(connection.getInputStream());
        System.out.println("connected to port"+connection.getLocalPort());
        try
        {
        message=(String)in.readObject();
        System.out.println(message);
        }
        catch(ClassNotFoundException e)
        {
            System.out.println("Exception is"+e);
        }
        message="";
        System.out.println("Enter the  number :");
        message1=stdin.readLine();
        out.writeObject(message1);
        out.flush();

        try
        {
        message=(String)in.readObject();
        System.out.println(message);
        }
        catch(ClassNotFoundException e)
        {
            System.out.println("Exception is"+e);
        }
        System.out.println(" The binary  form of  number is:"+message);

    }
    catch(UnknownHostException ae)
    {
        System.out.println("Exception is"+ae);
    }
    catch(IOException e)
    {
        System.out.println("Exception is"+e);
    }
    try
    {
    out.close();
        in.close();
        connection.close();
    }
    catch(IOException e)
    {
        System.out.println("Exception is"+e);
    }

}


public  static void main(String args[])throws IOException
{
    RequesterMain s=new RequesterMain();
    s.run();
}

}

ServerMain.java

import java.net.*; import java.io.*; class ServerMain {

ServerSocket server;
ObjectOutputStream out;
ObjectInputStream in;
Socket connection1=null;
String message,message1,message2="";
int i=7;
ServerMain(){}
void run()
{
    try
    {
        System.out.println("waiting  for  connection");
        message="hi  i  am server";
        server=new ServerSocket(19999,10);

        connection1=server.accept();
        System.out.println("connected to port"+connection1.getLocalPort());
        out=new ObjectOutputStream(connection1.getOutputStream());
        in=new ObjectInputStream(connection1.getInputStream());
        out.writeObject(message);
        out.flush();
        try
        {
        message1=(String)in.readObject();
        System.out.println(message1);
        }
        catch(ClassNotFoundException e)
        {
            System.out.println("Exception is"+e);
        }
        int m;
        int n=Integer.parseInt(message1);
        message1="";
        while(n>0)
        {
         m=n%2;
             message1=message1+m;
         n=n/2;

         i--;
        }
        System.out.println(message1);
         n=message1.length();
        System.out.println("string in reversed order is ");
        for(int i=n-1;i>=0;i--)
        {
        char c=message1.charAt(i);
        message2+=c;
        }

        out.writeObject(message2);
        out.flush();            

    }
    catch(UnknownHostException ae){
        System.out.println("Exception is"+ae);
    }
    catch(IOException e)
    {
        System.out.println("Exception is"+e);
    }
    try
    {
    out.close();
        in.close();
        connection1.close();
    }
    catch(IOException e)
    {
        System.out.println("Exception is"+e);
    }   }



public  static void main(String args[])throws IOException
{
    ServerMain s=new ServerMain();
    s.run();
}

}

run first ServerMain in one cmd and ReceiverMain.java in another cmd.