how do i implement this to function in serializable

[tohobaby]

i have write this layout but dunno how to write this 3 function in serializable...can u all help me? Y.Y
this was the question:

Write a programme to keep your friends telephone numbers. You should be able to;
a. Add a new name and number
b. Look up a number given a name
c. Save the data to an object file when you terminate the programme
d. Restore the saved data when the program is rerun

the layout:

import java.util.*;

class Menu {
	public static void main(String args[])throws Exception{
	 int option;
	   do {
	   	 menu();
	   	 option = getOption();
	   	 processOption(option);
	   }while (true);

	}

	private static void menu() {
	  System.out.println("1->Add new number");
	  System.out.println("2->Search new number");
	  System.out.println("3->Exit");
	  System.out.println("---------------------");
	}

	private static int getOption() throws Exception{
	  int option;
	  Scanner sc = new Scanner(System.in);
      System.out.print("Please enter an option: ");

      option = sc.nextInt();
      return option;
	}
	private static  void processOption(int o) throws Exception
		 {
	  switch(o){
	  	case 1:{
	  		System.out.println("You select one");

	  		break;
	  	    }
	  	case 2: {
	  		System.out.println("You select two");
	  		break;
	  	    }
	  	case 3: {
	  		System.out.println("Bye Bye");
	  		System.exit(0);
	  	   }
	  	default:
	  		System.out.println("Invalid option!");
	  }
	  	System.out.println("Press any key to continue");
	  	System.in.read();

	}
}