Exception in thread «main» java.lang.NullPointerException как устранить?

package Default;

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;

import javax.swing.JOptionPane;

public class Connect {
	int port = 2020;
	ServerSocket s;
	Scanner in ;
	PrintWriter w;

	private void connect() {
		Socket socket;
		try {
			socket = s.accept();
		} catch(IOException e) {
			JOptionPane.showMessageDialog(null, "Не могу установить соединение");
			return;
		}
		JOptionPane.showMessageDialog(null, "Соединение установлено");
		try { in =new Scanner(socket.getInputStream());
			w = new PrintWriter(socket.getOutputStream(), true);
		} catch(IOException e) {
			return;
		}
		JOptionPane.showMessageDialog(null, in);
	}

	public void sendClient(String command) {
    }

	public void Server() {
		try {
			s = new ServerSocket(port);
		} catch(IOException e) {
			JOptionPane.showMessageDialog(null, "Не могу создать сервер");
			System.exit(0);
		}

	}

	public void processing() {
		while (true) {
			connect();
		}
	}
}

Exception in thread "main" java.lang.NullPointerException
	at Default.Connect.connect(Connect.java:21)
	at Default.Connect.processing(Connect.java:54)
	at Default.Server.main(Server.java:8)