import java.util.*;

public class Cryptogram
{
	private static Vector encoded;
	private static Vector decoded;
	private static String message;
	private static Scanner keyboard;
	private static boolean noStarLeft;
	private static Character letterToBeReplaced;
	private static Character charToReplaceWith;
	private static boolean invalidTarget;
	private static boolean invalidReplace;
	private static Character input;
	private static boolean isDecoded;

	public static void main(String[] args) throws MissingLetterException,
			InvalidInputException
	{
		encoded = new Vector();
		decoded = new Vector();
		message = "A B C '";
		keyboard = new Scanner(System.in);
		noStarLeft = false;
		isDecoded = false;

		// encoded works fine
		for (int i = 0; i < message.length(); i++)
		{
			Character c = message.charAt(i);

			// making encoded
			encoded.add(c);

			// now making decoded
			if (Character.isLetter(c))
				decoded.add((Character) '*');
			else
				decoded.add(c);
		}

		while (!noStarLeft && !isDecoded)
		{
			invalidTarget = true;
			invalidReplace = true;

			System.out.println(encoded);
			System.out.println(decoded);

			while (invalidTarget)
			{
				System.out.print("Pick a letter from encoded message: ");
				input = (Character) keyboard.nextLine().toUpperCase().charAt(0);

				if (encoded.contains(input))
				{
					letterToBeReplaced = input;
					invalidTarget = false;
				}
				else
				{
					throw new MissingLetterException(
							"Letter was not found in encoded message");
				}
			}

			while (invalidReplace)
			{
				System.out.print("\nReplace with which letter (A-Z, *): ");
				input = (Character) keyboard.nextLine().toUpperCase().charAt(0);

				if (Character.isLetter(input) == true
						|| input.equals((Character) '*'))
				{
					charToReplaceWith = input;
					invalidReplace = false;
				}
				else
				{
					throw new InvalidInputException("Invalid Input.");
				}
			}

			for (int j = 0; j < encoded.indexOf(encoded.lastElement()); j++)
			{
				if (encoded.get(j).equals(letterToBeReplaced))
				{
					decoded.set(j, charToReplaceWith);
				}
			}

			if (decoded.contains((Character) '*'))
				noStarLeft = false;
			else
			{
				noStarLeft = true;

				System.out.print("\nIs the message decoded? ");

				input = (Character) keyboard.nextLine().toUpperCase().charAt(0);

				if (input == 'Y')
					isDecoded = true;
				else
					isDecoded = false;
			}
		}
	}
}