Complete Program:

// File: Restaurant.java
public class Restaurant
{
   private final double SOUP = 2.50;
   private final double WINGS = 0.15;
   private final double BURGER = 4.95;
   private final double CHICKENSANDWICH = 5.95;
   private final double FRIES = 1.99;
   private final double PIE = 2.95;
   private final double ICECREAM = 2.99;
   private final double SOFTDRINK = 1.50;
   private final double COFFEE = 1.00;
   private final double DISCOUNT = 0.25;
   private final double TAX = 0.05;

   private int age;
   private int soup;
   private int wings;
   private int burger;
   private int chickensandwich;
   private int fries;
   private int pie;
   private int icecream;
   private int softdrink;
   private int cofee;

   private double totalbill;

   public Restaurant()
   {
       this.age = 0;
       this.soup = 0;
       this.wings = 0;
       this.burger = 0;
       this.chickensandwich = 0;
       this.fries = 0;
       this.pie = 0;
       this.icecream = 0;
       this.softdrink = 0;
       this.cofee = 0;

       this.totalbill = 0.0;
   }

   public Restaurant(int age, int soup, int wings, int burger, int chickensandwich, int fries, int pie, int icecream, int softdrink, int cofee)
   {
       this.age = age;
       this.soup = soup;
       this.wings = wings;
       this.burger = burger;
       this.chickensandwich = chickensandwich;
       this.fries = fries;
       this.pie = pie;
       this.icecream = icecream;
       this.softdrink = softdrink;
       this.cofee = cofee;
       calculateTotalbill();
   }

   private void calculateTotalbill()
   {
       if(age <= 12)
           totalbill = 0;
       else
           totalbill = soup * SOUP + wings * WINGS + burger * BURGER + chickensandwich * CHICKENSANDWICH
                   + fries * FRIES + pie * PIE + icecream * ICECREAM + softdrink * SOFTDRINK + cofee * COFFEE;

       if((age >= 13 && age >= 18) || age >= 65)
           totalbill = totalbill - totalbill * DISCOUNT;

       if(age <= 12 || (age > 18 && age < 65))
           totalbill = totalbill + totalbill * TAX;
   }

   public double getTotalbill()
   {
       return totalbill;
   }

   public int getAge()
   {
       return age;
   }
}

// File: RestaurantBill.java
import java.util.*;
public class RestaurantBill
{
   public static void main(String[] args)
   {
       Scanner input = new Scanner(System.in);
       int n;
       int age;
       int soup;
       int wings;
       int burger;
       int chickensandwich;
       int fries;
       int pie;
       int icecream;
       int softdrink;
       int cofee;
       int count;
       int more = 0;

       do
       {
           System.out.print("Number of persons: ");
           n = input.nextInt();

           Restaurant[] orders = new Restaurant[n];

           System.out.println("Every person who eats at this restaurant orders exactly three items. Never greater, never fewer.");

           for(int i = 0; i < n; i++)
           {
               soup = 0;
               wings = 0;
               burger = 0;
               chickensandwich = 0;
               fries = 0;
               pie = 0;
               icecream = 0;
               softdrink = 0;
               cofee = 0;
               count = 0;
               System.out.println("Enter order for person " + (i + 1) + ":");

               System.out.print("Age: ");
               age = input.nextInt();

               System.out.print("Soup: ");
               soup = input.nextInt();

               if(soup > 0)
                   count++;

               System.out.print("Wings: ");
               wings = input.nextInt();

               if(wings > 0)
                   count++;

               System.out.print("Burger: ");
               burger = input.nextInt();

               if(wings > 0)
                   count++;

               if(count == 3)
               {
                   System.out.println("You ordered three items. Thank you.");
                   orders[i] = new Restaurant(age, soup, wings, burger, chickensandwich, fries, pie, icecream, softdrink, cofee);
               }
               else
               {
                   System.out.print("Chickensandwich: ");
                   chickensandwich = input.nextInt();

                   if(chickensandwich > 0)
                       count++;

                   if(count == 3)
                   {
                       System.out.println("You ordered three items. Thank you.");
                       orders[i] = new Restaurant(age, soup, wings, burger, chickensandwich, fries, pie, icecream, softdrink, cofee);
                   }
                   else
                   {
                       System.out.print("Fries: ");
                       fries = input.nextInt();

                       if(fries > 0)
                           count++;

                       if(count == 3)
                       {
                           System.out.println("You ordered three items. Thank you.");
                           orders[i] = new Restaurant(age, soup, wings, burger, chickensandwich, fries, pie, icecream, softdrink, cofee);
                       }
                       else
                       {
                           System.out.print("Pie: ");
                           pie = input.nextInt();

                           if(pie > 0)
                               count++;

                           if(count == 3)
                           {
                               System.out.println("You ordered three items. Thank you.");
                               orders[i] = new Restaurant(age, soup, wings, burger, chickensandwich, fries, pie, icecream, softdrink, cofee);
                           }
                           else
                           {
                               System.out.print("Icecream: ");
                               icecream = input.nextInt();

                               if(icecream > 0)
                                   count++;

                               if(count == 3)
                               {
                                   System.out.println("You ordered three items. Thank you.");
                                   orders[i] = new Restaurant(age, soup, wings, burger, chickensandwich, fries, pie, icecream, softdrink, cofee);
                               }
                               else
                               {
                                   System.out.print("Softdrink: ");
                                   softdrink = input.nextInt();

                                   if(softdrink > 0)
                                       count++;

                                   if(count == 3)
                                   {
                                       System.out.println("You ordered three items. Thank you.");
                                       orders[i] = new Restaurant(age, soup, wings, burger, chickensandwich, fries, pie, icecream, softdrink, cofee);
                                   }
                                   else
                                   {
                                       System.out.print("Cofee: ");
                                       cofee = input.nextInt();

                                       if(cofee > 0)
                                           count++;

                                       if(count == 3)
                                       {
                                           System.out.println("You ordered three items. Thank you.");
                                           orders[i] = new Restaurant(age, soup, wings, burger, chickensandwich, fries, pie, icecream, softdrink, cofee);
                                       }
                                       else
                                       {
                                           System.out.println("You ordered less than three items. Give the order again.");
                                           i--;
                                       }
                                   }
                               }
                           }
                       }
                   }
               }
           }

           System.out.printf("\n%-10s%4d%10.2f\n", "PERSON#", "AGE", "TOTALBILL");
           double grandTotal = 0;
           for(int i = 0; i < n; i++)
           {
               System.out.printf("%-10d%4d%10.2f\n", (i + 1), orders[i].getAge(), orders[i].getTotalbill());
               grandTotal = grandTotal + orders[i].getTotalbill();
           }
           System.out.printf("Grand tatal = $ %.2f\n" + grandTotal);

           System.out.print("\nEnter 1 if there is one more family wants to give order: ");
           more = input.nextInt();
           System.out.println();
       }while(more == 1);
   }
}