server

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

public class CalcServer {
    public static void main(String [] args) throws Exception {
       int port = 1000;
       double a=0 ;
       double b=0 ;
       double res;
       String resp;
       ServerSocket Ss = new ServerSocket(port);
       while(true){
       Socket sk = Ss.accept();
       BufferedReader infromClient = new BufferedReader(
       new InputStreamReader(sk.getInputStream()));
       DataOutputStream outClient = new DataOutputStream(sk.getOutputStream());

       String line = infromClient.readLine();
       String [] tokens = line.split(" ");
       if(tokens.length != 3){
           resp = "parsing error";
       }
       try {
          a = Double.parseDouble(tokens[0]);
          b = Double.parseDouble(tokens[2]);
       }
       catch(Exception e){
          resp = "Invalid arguments";
       }
       if(tokens[1].equals("+")){
           res = a + b;
           resp = Double.toString(res);
       }
       else if(tokens[1].equals("-")){
           res = a-b;
           resp = Double.toString(res);
       }
       else if(tokens[1].equals("*")){
           res = a*b;
           resp = Double.toString(res);
       }
       else if(tokens[1].equals("/")){
           res = a/b;
           resp = Double.toString(res);
       }
       else {
           resp = "invalid math operation";
       }
       outClient.writeBytes(resp);
       infromClient.close();
       outClient.close();
       }

    }

}



package calcu;
import java.io.*;
import java.net.Socket;

public class CalClient {
    public static void main(String [] args){

        String sent;
        String res;
        try{
        Socket s =  new Socket("localhost",1000);
        BufferedReader infromUser = new BufferedReader(new InputStreamReader(System.in));
        DataOutputStream outToServer = new DataOutputStream(s.getOutputStream());
        BufferedReader infromServer = new BufferedReader(new InputStreamReader(s.getInputStream()));

        sent = infromUser.readLine();
        outToServer.writeBytes(sent+'\n');
        res = infromServer.readLine();
        System.out.println("from server : result "+ res);
     }
     catch (Exception e){
         e.printStackTrace();
     }

    }
}