java.lang.NullPointerException

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Date: 26 Mar 2005 15:34:47 -0800

Hi there I was wondering if someone can help me. I m fairly new to
java. I m developing a game where a user is trying to guess the letter
of an hindden word.

I ve developed 4 classes but I ve got problem with only 1 the class
Guesser.

1st class;

import java.io.*;

public class EasyInput
{

    BufferedReader in = new BufferedReader(new
InputStreamReader(System.in));

    public char readChar()
    {
        char c = 0;

        try
        {
            String str = in.readLine();

            if( !str.equals(""))
            {
                c = str.charAt(0);
            }
        }
        catch(Exception e)
        {
            System.out.println("Sorry, character input is required
here.");
        }

        return c;
    }
}

2nd class;

public class Player
{
  private String name;
  private int score;

    public void setName(String n)
    {
     name = n;
    }

  public String getName()
    {
     return name;
    }

  public void incrementScore()
    {
     score++;
    }

  public int getScore()
    {
     return score;
    }

  public boolean sameScore(Player p)
    {
     return (score == p.getScore());
    }

  public String toString()
    {
     String nameScore;
     nameScore = name + " ("+score + " points).";
     return nameScore;
    }

  public Player(String aPlayerName)
    {
     name = aPlayerName;
     score = 0;
    }

}

3rd class;

public class Guesser extends Player
{
  private char guess;
  private int turns;
  private char[]guessedAlready;

  public final static int MAX_RIGHT_GUESSES = 26;
  private final static char EXIT_CHARACTER = '*';

  public Guesser(String aName)
    {
     super(aName);
     turns = 0;
     guess = '\u0000';
     char[]guessedAlready = new char[MAX_RIGHT_GUESSES];
    }

  // method to tell if the received character is
  // a lowercase letter of the English alphabet
  public boolean isLetter(char ch)
    {
     if(ch >= 'a' && ch <= 'z')
       return true;
    else
       return false;
    }

  //return true if the received character has been
  // stored in the guessedAlready array before, otherwise return false
    public boolean isGuessedAlready(char ch)
    {
    int i = 0;
    boolean guessed = false;
    while(i < MAX_RIGHT_GUESSES)
       {
        if(ch == guessedAlready[i])
          {
           guessed = true;
           i++;
          }
        else
           i++;
        }
    return guessed;
    }

  // return true if a valid letter or exit character
  // is received as argument, otherwise it returns false

    public boolean isValid(char ch)
    {
      boolean valid = false;
     if((isLetter(ch)&& !isGuessedAlready(ch))|| ch == EXIT_CHARACTER)
        valid = true;
     if(!isLetter(ch))
        System.out.println("We \'re only using lower-case letters");
     if(!isGuessedAlready(ch))
        System.out.println("You guessed that one already!");
    return valid;
    }

  // a method to get a character from the keyboard
  private char readChar()
  {
    return new EasyInput().readChar();
  }

  // guess is set to either the exit character
  // or a valid guess (lowercase letter, not guessed already).

    public void setGuess(String prompt)
    {
     System.out.println(prompt);
     if(this.isLetter(readChar())&& !this.isGuessedAlready(readChar()))
        {
         guess = readChar();
         guessedAlready[turns] = guess;
         turns++;
        }
     else
        guess = EXIT_CHARACTER;
    }

  // return the value of the guess variable
    public char getGuess()
    {
     return guess;
    }

  // to return the value of the exit character
  public char getExitCharacter()
    {
     return EXIT_CHARACTER;
    }

  // Write a toString method
    public String toString()
  {
    String z = "";
    for(int i = 0; i < MAX_RIGHT_GUESSES; i++)
         {
         z = z + guessedAlready[i];
         }
    return super.toString()+ " Guesses [ "+ z +" ]";

  }
}

I cannot understand why I get the following error:

java.lang.NullPointerException

        at Guesser.toString(Guesser.java:120)

        at TestGuesser.main(TestGuesser.java:25)

Exception in thread "main"

Can anyone point me to the right direction????
Thanks Max :-)

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