/** Let's experiment with some exception handling in Java
 *  Read a menu, and find the average price of the items.
 */
import java.io.*;
import java.util.*;

public class Driver
{
  public static void main(String [] args) throws IOException
  {
    BufferedReader in = null;

    try
    {
      in = new BufferedReader(new FileReader("menu.txt"));
    }
    catch (FileNotFoundException e)
    {
      System.out.println("Sorry, can't find menu file.");
      System.exit(1);
    }

    // Read lines of text from the menu file.  Each line contains an item
    // and a price.  Keep track of sum so we can figure the average.
    double sumPrices = 0.0;
    int numItems = 0;
    while(true)
    {
      String line = in.readLine();
      if (line == null)
	break;

      // Let's assume we can separate the tokens by a space.
      // Later, to make the program more robust, we can handle menu items
      // that are more than one word.
      StringTokenizer tok = new StringTokenizer(line, " ");

      // The price is the 2nd token, so skip first token.
      try
      {
        tok.nextToken();
        sumPrices += Double.parseDouble(tok.nextToken());
        ++numItems;
      }

      // If the line of text is not of the form [item, price], skip it.
      catch (NoSuchElementException e)
      {
	continue;
      }

      // If there's a number format exception,  also skip.
      catch (NumberFormatException e)
      {
	continue;
      }
    }
    in.close();

    double average = sumPrices / numItems;
    System.out.printf("Average menu item price is $ %.2f\n", average);
  }
}