Server

package serverelisa;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;

public class ServerElisa {

    boolean stop = true;
    Socket socket;
    int n = 0;

    ServerElisa() {
        try {
            ServerSocket ss = new ServerSocket(33061);
            while (stop) {
                System.out.println("Receiving data:");
                try {
                    socket = ss.accept();
                    DataInputStream in = new DataInputStream(socket.getInputStream());

                    String[] str = in.readUTF().split(" ");

                    if (!str[0].equals("")) {
                        System.out.println(str[0] + " " + str[1] + " " + str[2]);

                        int a = Integer.parseInt(str[0]);
                        char s = str[1].charAt(0);
                        int b = Integer.parseInt(str[2]);

                        if(s=='+'){
                            n=a+b;
                        }else if(s=='*'){
                            n=a*b;
                        }else if(s=='-'){
                            n=a-b;
                        }else if(s=='/'){
                            n=a/b;
                        }

                        stop = false;
                    }

                    socket.close();

                } catch (IOException ex) {
                    //Logger.getLogger(Client.class.getName()).log(Level.SEVERE, null, ex);
                }
            }

            System.out.println("Connection closed");

        } catch (IOException ex) {
            Logger.getLogger(ServerElisa.class.getName()).log(Level.SEVERE, null, ex);
        }

        try {
            socket = new Socket("127.0.0.1", 1000);
            DataOutputStream tmpOut = new DataOutputStream(socket.getOutputStream());
            tmpOut.writeUTF(n + "");
            System.out.println("sent");
            tmpOut.flush();
        } catch (IOException ex) {
            Logger.getLogger(ServerElisa.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    public static void main(String[] args) {
        ServerElisa se = new ServerElisa();
    }

}