Thread: I need help with ArrayIndexOutOfBounds exception!

Hi all,

I am writing a program for school, and am stuck. The program is throwing an ArrayIndexOutOfBounds exception, which I realize means that my array has an index that is less than zero, but I can't see how that's happening. Can you please look over my code and see if it's something obvious? The program generates a random number and then compares a user guess to that number and provides feedback regarding how close the guess is. The problem happens about halfway down at "engine.generateNewSecret()". When I run this method independently, it will create the array without a problem, but inside of the 'mother' program it throws the exception.

Here you go:

import java.util.Scanner;
 
public class Bagel {
 
	public static void main(String[] args) {
 
		System.out.println("Welcome!"); // it's nice to be nice :)
 
		Scanner keyboard = new Scanner(System.in);
		Engine engine = new Engine(); // declare object instances for this class
		Player player = new Player();
		Validator validator = new Validator();
 
		boolean reset = true; // menu switch
 
		while (reset == true) {
 
			System.out.println("\nEnter the number of digits to use: ");
			engine.numDigits = keyboard.nextByte(); // gets the numDigits
 
 
			System.out.println("\nEnter the player's name: ");
			player.name = keyboard.next(); // gets the player's name
 
			boolean play = true; // menu switch
 
			while (play == true) {
				for (int gameCount = 1; gameCount > 0; gameCount++) {
					System.out.println("\n Starting game " + gameCount);
 
					engine.generateNewSecret(); // [B]here's the problem![/B]
					int numberOfGuesses = 0;
					int newNumberOfGuesses;
					while (true) {
						newNumberOfGuesses = numberOfGuesses;
						System.out.println("\nEnter guess: ");
						player.askForGuess();
						validator.validateGuess(engine.getSecret(),
								player.guess, engine.getNumDigits());
						if (validator.validateGuess(engine.getSecret(),
								player.guess, engine.getNumDigits()) == false) 
						{
							numberOfGuesses++;
							continue;
						}
 
						else
							break;
					}
					gameCount++;
					System.out.println("Congratulations! You won in "
							+ numberOfGuesses + "moves!");
					if (newNumberOfGuesses < numberOfGuesses)
						player.fastestWin = newNumberOfGuesses;
					else
						player.fastestWin = numberOfGuesses;
					System.out.println("\nStatistics for " + player.name + ":");
					System.out.println("\nGames completed: " + gameCount);
					System.out.println("\nNumber of digits: "
							+ engine.getNumDigits());
					System.out.println("\nFastest win: " + player.fastestWin);
				}
				System.out.println("p - Play again\nr - Reset game\nq - Quit");
				System.out.println("\nWhat would you like to do?");
				String menu = keyboard.nextLine().trim().toLowerCase().substring(0,1);
				if (menu == "p")
					play = true;
				else if (menu == "r") {
					play = false;
					reset = true;
				} else if (menu == "q")
				{
					System.out.println("/nGoodbye!");
					System.exit(0);
 
 
				}
 
 
			}
 
		}
 
	}
 
}

Here's the code for the Engine class:

 
import java.util.Random;
 
 
public class Engine {
	Random random = new Random();
	byte numDigits;
	byte[] secretNumber = new byte[numDigits];
 
 
 
 
 
public void generateNewSecret()
{
	 int number = random.nextInt(((int)Math.pow(10, numDigits) - ((int)Math.pow(10, numDigits-1)))) + ((int)Math.pow(10, numDigits-1));
	 int temp = numDigits;
	 for (int i = 0; i < numDigits; i++)
		{
 
		    secretNumber[i] = (byte)((number/(Math.pow(10, temp-1))));  // [B]Exception here![/B]
		    if (number<10)
		    	break;
			number = number%((int)(Math.pow(10, temp-1)));
 
			temp--;
 
		}
}
 
public byte getNumDigits()
{
	return numDigits;
}
public byte[] getSecret()
{
	return secretNumber;
}
 
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
 
	}
 
}