Homework - Java.security.AccessControlException? Urgent!

import java.io.*;
import java.net.*;
import javax.swing.*;
 
public class AppletClient extends JApplet {
  // Label for displaying the visit count
  private JLabel jlblCount = new JLabel();
 
  // Indicate if it runs as application
  private boolean isStandAlone = false;
 
  // Host name or ip
  private String host = "localhost";
 
  /** Initialize the applet */
  public void init() {
    add(jlblCount);
 
    try {
      // Create a socket to connect to the server
      Socket socket;
      if (isStandAlone)
        socket = new Socket(host, 8000);
      else
        socket = new Socket(getCodeBase().getHost(), 8000);
 
      // Create an input stream to receive data from the server
      DataInputStream inputFromServer =
        new DataInputStream(socket.getInputStream());
 
      // Receive the count from the server and display it on label
      int count = inputFromServer.readInt();
      jlblCount.setText("You are visitor number " + count);
 
      // Close the stream
      inputFromServer.close();
    }
    catch (IOException ex) {
      ex.printStackTrace();
    }
  }
 
  /** Run the applet as an application */
  public static void main(String[] args) {
    // Create a frame
    JFrame frame = new JFrame("Applet Client");
 
    // Create an instance of the applet
    AppletClient applet = new AppletClient();
    applet.isStandAlone = true;
 
    // Get host
    if (args.length == 1) applet.host = args[0];
 
    // Add the applet instance to the frame
    frame.add(applet, java.awt.BorderLayout.CENTER);
 
    // Invoke init() and start()
    applet.init();
    applet.start();
 
    // Display the frame
    frame.pack();
    frame.setVisible(true);
  }
}

import java.io.*;
import java.net.*;
import java.util.*;
import java.awt.*;
import javax.swing.*;
 
public class Server extends JFrame {
  // Text area for displaying contents
  private JTextArea jta = new JTextArea();
 
  public static void main(String[] args) {
    new Server();
  }
 
  public Server() {
    // Place text area on the frame
    setLayout(new BorderLayout());
    add(new JScrollPane(jta), BorderLayout.CENTER);
 
    setTitle("Server");
    setSize(500, 300);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setVisible(true); // It is necessary to show the frame here!
 
    try {
      // Create a server socket
      ServerSocket serverSocket = new ServerSocket(8000);
      jta.append("Server started at " + new Date() + '\n');
 
      // Listen for a connection request
      Socket socket = serverSocket.accept();
 
      // Create data input and output streams
      DataInputStream inputFromClient = new DataInputStream(
        socket.getInputStream());
      DataOutputStream outputToClient = new DataOutputStream(
        socket.getOutputStream());
 
      while (true) {
        // Receive radius from the client
        double radius = inputFromClient.readDouble();
 
        // Compute area
        double area = radius * radius * Math.PI;
 
        // Send area back to the client
        outputToClient.writeDouble(area);
 
        jta.append("Radius received from client: " + radius + '\n');
        jta.append("Area found: " + area + '\n');
      }
    }
    catch(IOException ex) {
      System.err.println(ex);
    }
  }
}