null pointer exception in multi threading

Guys, I am getting null pointer exception in my server multi threading code.
The error occurs towards the end of the code where I close my server (server.close();)

I have intialized the server with a null value inside run(). But actually i want to close the server which i created inside main(). But I cant access it from outside main(). how do i solve this issue???

Code:

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import java.io.*;
import java.net.*;
import java.util.logging.Level;
import java.util.logging.Logger;

public class server implements Runnable {

    Socket socket = null;

    public server(Socket socket) {
        this.socket = socket;
    }

    public static void main(String args[]) {

        ServerSocket server = null;
        Socket socket = null;

        try {
            //create socket
            server = new ServerSocket(5000, 100);
            System.out.println("Waiting for connection");

        } catch (IOException ex) {
            Logger.getLogger(server.class.getName()).log(Level.SEVERE, null, ex);
        }
        while (true) {
            try {
                //accept nxt connection request
                socket = server.accept();
                System.out.println("Connection received from " + socket.getInetAddress().getHostName());

                server myServer = new server(socket);
                Thread t = new Thread(myServer);
                Thread t1 = Thread.currentThread();
                String name = t1.getName();
                t.start();
                System.out.println(" thread name is:" +name);

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

    public void run() {

        ObjectInputStream in = null;
        ObjectOutputStream out = null;
        boolean exit = false;
        ServerSocket server = null;

        try {
            //get input and output streams
            out = new ObjectOutputStream(socket.getOutputStream());
            in = new ObjectInputStream(socket.getInputStream());
            System.out.println("Connection successfull");
           
            //reading input string
            String inputStr = (String) in.readObject();
            System.out.println("client> " + inputStr);
            if (!inputStr.equals("exit")) {
                if (inputStr.equals("vivek")) {
                    out.writeObject("Granted");
                } else {
                    out.writeObject("Denied");
                }
            } else {
                exit = true;
                out.writeObject("exiting");
            }
            //close connection
            in.close();
            out.close();
            socket.close();
        } catch (IOException ex) {
            Logger.getLogger(server.class.getName()).log(Level.SEVERE, null, ex);
        } catch (Exception e) {
            System.err.println("Exception: " + e.getMessage());
            e.printStackTrace();
        } finally {
            try {
                server.close();
            } catch (IOException ex) {
                Logger.getLogger(server.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }
}

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Just use basic OOPs techniques. Give the server class a private ServerSocket variable and pass a reference to the ServerSocket created in main into your "server" class object via its constructor or via a public setServerSocket method that you create.

how do I do that? this si what I did. is it correct?

Code:

---


 private ServerSocket server = null;



    public server(Socket socket, ServerSocket server) {
        this.socket = socket;
        this.server = server;
    }

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Quote:

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Originally Posted by niteangell21

how do I do that? this si what I did. is it correct?

Code:

---


 private ServerSocket server = null;



    public server(Socket socket, ServerSocket server) {
        this.socket = socket;
        this.server = server;
    }

---

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So far looks OK, but bottom line is, does it work? Does it fix your problem?

no it didnt. still getting null pointer exception

Quote:

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Originally Posted by niteangell21

no it didnt. still getting null pointer exception

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So debug it. Find the line that has the NPE, see which object is null, and then trace back in your code to find out why the object hasn't been initialized.