Write program in which server listens on port for incoming connection from client program. When server connects to a client it reads one line of text from client, reverse chars in a line and sends them back to the client.

Source Code:

Client side:

import java.io.*;

import java.net.*;

import java.util.*;

class tcpclient

{

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

      {

                  Scanner sc=new Scanner(System.in);

                  System.out.println("Enter Port:");

                  int port=sc.nextInt();                                

                  Socket soc=new Socket(InetAddress.getLocalHost(),port);

                  InputStream in=soc.getInputStream();

                  OutputStream out=soc.getOutputStream();            

                  System.out.println("Give your data:");

                  String str;

                  str=sc.next();                      

                  byte buf[]=str.getBytes();

                  out.write(buf);                   

                  int c;

                  str="";

                  byte buff[]=new byte[100];

                  c=in.read(buff);

                  for(int i=0;i<c;i++)

                              str = str+(char)buff[i];

                  System.out.print("Reverse string received from server is : "+str);                     

      }

}

Server side

import java.net.*;

import java.io.*;

import java.util.*;

class tcpserver

{

      public static void main(String args[]) throws IOException

      {

                  Scanner sc=new Scanner(System.in);             

                  System.out.println("Enter Port:");

                  int port=sc.nextInt();                    

                  ServerSocket ss=new ServerSocket(port);

                  System.out.println("Waiting for Client...");

                  Socket soc=ss.accept();               

                  InputStream in=soc.getInputStream();

                  OutputStream out=soc.getOutputStream();            

                  String str = " ";

                  byte buf[]=new byte[100];

                  int n=in.read(buf);

                  for(int i=0;i<n;i++)

                              str = str+(char)buf[i];

                  System.out.println("Received: "+str);             

                  String str1 = " ";

                  for(int i = str.length()-1;i>=0;i--)

                              str1 = str1+str.charAt(i);

                  byte buff[] = str1.getBytes();

                  System.out.println("Writing to client");

                  out.write(buff);

      }

}  

Output: