[JAVA] Lỗi không không chạy được

[12520276]

Hiện tại mình có 2 flie ,Client - kết nối -Server . Nhưng khi run file server.java thì bị lỗi.Nhờ mọi người giúp mình.

import java.io.*;
import java.net.*;

public class Server {
    public static void main(String[] argv) throws Exception{
        ServerSocket welcomeSocket= new ServerSocket(6789);
        while(true){
            Socket connectSocket = welcomeSocket.accept();
            BufferedReader inFormClient =new BufferedReader(new InputStreamReader(connectSocket.getInputStream()));
            //doc data
           String c = inFormClient.readLine();
           String d = inFormClient.readLine();  
           float a = Float.parseFloat(c);
           float b = Float.parseFloat(d);
           float sum = a+b;
           String result = sum + "\n";
           
       //Gui data ve cho Client
       DataOutputStream outToClient = new DataOutputStream(connectSocket.getOutputStream());
       outToClient.writeBytes(result);
       
    }
    }
}

Client.java

import java.io.*;
import java.net.*;

public class Client {
  
                                     
   
    public static void main(String argv[]) throws Exception{
        String a,b;
        
        Socket clientSocket = new Socket("NguyenNam",8888);
        BufferedReader inFormUse =new BufferedReader(new InputStreamReader(System.in));
            //Nhap data vao
        System.out.println("a = ");
        a=inFormUse.readLine();
        System.out.println("b = ");
        b=inFormUse.readLine();
        
            //
        DataOutputStream outToServer =new DataOutputStream(clientSocket.getOutputStream());
            
            
            //Gui data toi server
        outToServer.writeBytes(a + "" );
        outToServer.writeBytes(b + "");
            //
        BufferedReader inFormServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
            
            //Doc data tu server ve
        String result=inFormServer.readLine();
        System.out.print("CLient");
            
            //Dong ket noi 
        
        clientSocket.close();
    
      
        
    }
                           
}