Hangman Game Using Class - It Keeps On Bringing Up Exception Error

I wrote a program that would play a game of Hangman. It plays the game but it keeps on bringing up a exception error. This is my class code

import java.util.ArrayList;
class Assignment2Q4
{
private final ArrayList<Character> guessList = new ArrayList<>();
private final char[] charArray;
private final String secretWord;
private int guesses;

[Code] ....

This is the output that is given:

Enter the secret word:
pizza
Guess a letter:
d
?????
Guess a letter:

[Code] .....

Also when I guess the first letter of the word correctly it stops the program without going further on with the guessing.

Like for ex. P????