I don't understand how to use ObjectInputStream

Question

When I compile the below program, it gives me a "grade_c.java:87: Exception java.lang.ClassNotFoundException must be caught, or it must be declared in the throws clause of this method.
                    String today = (String)s.readObject();"
error. Can anyone tell me what I'm doing wrong?
//Mini-Project Grade C, by Gopinath Chandran, (18.04.2003)
//Fixtures Database to store 2003 FA Cup Semi finals
//Import neeeded classes
import javax.swing.*;
import java.util.*;
import java.io.*;
public class grade_c
     //used to count how many fixtures have been added
     static int num_fixtures = 0;
     public static void main (String[] args) throws IOException
     {//main
          //used to store users input
          int choice = 0; //used to store menu option entered
          int fixture_replace = 0; //used to store which fixture to change
          //declare reference to an array
          Fixture array[];
          array = new Fixture[4];
               choice = menu();          
          //While the user hasn't selected quit
          while (choice != 6)
               //Run main menu
               //If user chooses to enter a new fixture
               if (choice == 1)
                    //Check to see if all fixtures have been entered
                    if (num_fixtures == 4)
                         fixture_replace = Integer.parseInt(JOptionPane.showInputDialog("All fixtures have been entered, please enter which fixture to be replaced (1-4):\n"));
                           array[fixture_replace-1].home = JOptionPane.showInputDialog("Pleae enter the home team for this fixture, eg. Arsenal:\n");
                         array[fixture_replace-1].away = JOptionPane.showInputDialog("Pleae enter the away team for this fixture, eg. Tottenham:\n");          
                         array[fixture_replace-1].day = Integer.parseInt(JOptionPane.showInputDialog("Please enter the day from the date of this fixture, eg 9 or 17:\n"));
                         array[fixture_replace-1].month = Integer.parseInt(JOptionPane.showInputDialog("Please enter the month from the date of this fixture, eg 3 or 10:\n"));
                    //If less than 4 fixtures have been entered, ask user to input new fixture
                    else
                         array[num_fixtures] = new Fixture();
                         num_fixtures = num_fixtures + 1;                         
               if (choice == 2)
                    for (int i = 0; i<num_fixtures; ++i)
                         System.out.print("\n");
                         array.printFixture();
               if (choice == 3)
                    for (int counter = 0; counter < (num_fixtures); counter++)
                         if (array[counter].home.equals("Arsenal"))
                              System.out.print("\n\nItem was found at position" + counter + ".");; // return position where found
                              System.out.print("\n" + array[counter].home);
                         else
                              System.out.print("\n\nItem not found at " + counter + "!");
                              System.out.print("\n" + array[counter].home);
               if (choice == 4)
                    FileInputStream in = new FileInputStream("theTime");
                    ObjectInputStream s = new ObjectInputStream(in);
                    String today = (String)s.readObject();
                    Fixture test1 = (Fixture)s.readObject();
               if (choice == 5)
                    FileOutputStream out = new FileOutputStream("theTime");
                    ObjectOutputStream s = new ObjectOutputStream(out);
                    s.writeObject("Today");
                    s.writeObject(new Fixture());
                    s.flush();
               choice = menu();
          //Exit process
          System.out.print("\n\n\n\n");
          System.exit(0);
     static int menu()
          //used to store users input
          String temp;
          int a;
          //Asks the user if they want to enter a new date
          temp = JOptionPane.showInputDialog(null, "FA Cup 2003 Quarter Finals Fixtures (c) Go-Pez-Go Productions 2003\n\nMain Menu:\n\n1. Enter new fixtures [" + (num_fixtures) + " entered]\n2. Print Fixtures Entered\n3. Search for a team\n4. Load fixtures\n5. Save fixtures\n6. Quit\n");
          a = Integer.parseInt(temp);
          return a;     
class Fixture implements Serializable
     public String home;
     public String away;
     public int day;
     public int month;
     //Initialise a new Date object with the values passed
     public Fixture (String h, String a, int d, int m)
          home = h;
          away = a;
          day = d;
          month = m;
     public Fixture()
          home = JOptionPane.showInputDialog("Pleae enter the home team for this fixture, eg. Arsenal:\n");
          away = JOptionPane.showInputDialog("Pleae enter the away team for this fixture, eg. Tottenham:\n");          
          day = Integer.parseInt(JOptionPane.showInputDialog("Please enter the day from the date of this fixture, eg 9 or 17:\n"));
          month = Integer.parseInt(JOptionPane.showInputDialog("Please enter the month from the date of this fixture, eg 3 or 10:\n"));
     //method to print objects instance variables
     public void printFixture()
     System.out.print("\n" + home + " vs " + away + ", " + day + "/" + month + "/2003" + ".");

Answer 1

"grade_c.java:87: Exception java.lang.ClassNotFoundException must be caught"This error message is telling you to catch the exception. So...
try
  //your code
catch(java.lang.ClassNotFoundException exception)
  exception.printStackTrace();
}