import java.util.Scanner;
import java.util.Hashtable;
import java.util.Enumeration;
import java.util.StringTokenizer;
import java.io.FileInputStream;
import java.io.FileNotFoundException;

/** Example of using a Java hash table (with 'keys' and 'values')
 *  In this example, we have different foods and what kinds (groups) they are.
 *  The hash table functions we will practice are:
 *    put, get, containsKey, containsValue, keys, toString
 *  Note:  a HashMap would do pretty much the same thing as a Hashtable.
 *
 *  Basically, we now have an array-type data structure that can be
 *  indexed by anything, such as by string.
 */
public class Driver
{
  public static void main(String [] args) throws FileNotFoundException
  {
    Scanner in = new Scanner(new FileInputStream("food.txt"));
    Scanner kbd = new Scanner(System.in);
    Hashtable table = new Hashtable();

    while(in.hasNextLine())
    {
      String line = in.nextLine();

      // On each line of input, we have a key and a value such as
      // banana = fruit   --> banana is the key & fruit is the value
      // We want to tell Java that banana is a kind of fruit....
      StringTokenizer tok = new StringTokenizer(line, "=");
      String key = tok.nextToken().trim();
      String value = tok.nextToken().trim();

      table.put(key, value);
    }

    // Now, we can print out the hashtable.  It has its own toString(),
    // and notice that the order is not the same as we read in.
    System.out.printf("\n%s\n", table);


    // Look up keys in the hash table.
    System.out.printf("\nEnter a food, and I'll tell you what kind it is:  ");
    String choice = kbd.nextLine();
    if (! table.containsKey(choice))
      System.out.printf("Sorry, I don't have %s on the menu.\n", choice);
    else
      System.out.printf("%s is a %s.\n", choice, table.get(choice));


    // Look up values in the hash table.
    System.out.printf("\nWhat type of food do you want?  ");
    choice = kbd.nextLine();
    if (table.containsValue(choice))
    {
      System.out.printf("Yes, I do have some %s.\n", choice);

      // Find all the foods that belong to that food group.
      // For some strange reason, keys() returns an Enumeration.
      Enumeration<String> foods = table.keys();
      while(foods.hasMoreElements())
      {
        String food = foods.nextElement();
        if (table.get(food).equals(choice))
          System.out.printf("\t%s\n", food);
      }
    }
    else
      System.out.printf("Sorry, I don't have any %s.\n", choice);
  }
}