gistfile1.java

package tcp;
import java.io.*; 
import java.net.*; 

/**
 *
 * @author Rashid
 */
public class Server {
        public static void main(String[] args ) throws Exception{
            
       String clientSentence; 
      String capitalizedSentence; 

      // Creating Server Port 6789
      ServerSocket welcomeSocket = new ServerSocket(6789); 
      System.out.println("Server Started and listening to the port 6789");

  
      while(true) { 
          
  // The server accepts the waiting client
            Socket connectionSocket = welcomeSocket.accept(); 
 // IN           
BufferedReader inFromClient = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream())); // OUT
DataOutputStream  outToClient = new DataOutputStream(connectionSocket.getOutputStream()); 

           // READ LINE
           clientSentence = inFromClient.readLine();
           // UPPER CASE 
           capitalizedSentence = clientSentence.toUpperCase() + '\n'; 
           outToClient.writeBytes(capitalizedSentence); 
        
        } 
    } 
} 
 

gistfile2.java

package tcp;
import java.io.*; 
import java.net.*; 

public class TCP {

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

// File Reading
//-----------------

// -----------------

 // Open Connection to the Port 6789
 // First Parameter is Server-Address and Second: is the  Port
    Socket clientSocket = new Socket("localhost",6789);
  BufferedReader inFromUser =  new BufferedReader(new InputStreamReader(System.in)); 

	PrintWriter toServer = null;
    	toServer = new PrintWriter(clientSocket.getOutputStream(), true);
        
    DataOutputStream outToServer =  new DataOutputStream(clientSocket.getOutputStream()); 

    }
    
}