Really frustrating Null Pointer Exception

Question

Hi I had the day off and was bored so I decided to start work on a poker game. Today I just started making a deck of cards and drawing a random card from it. However it isn't working as I get a very annoying null pointer exception which I don't understand. Anyway I will post my code:
public class DeckOfCards
     public static void main(String args[])
          Deck daDeck = new Deck();
          Card[] drawnCards = new Card[10];
          for (int i=0; i < 10; ++i)
               drawnCards[i] = daDeck.DrawCard();
               System.out.println(drawnCards.getTitle());
import java.util.*;
public class Deck
     Suit Hearts;
     Suit Diamonds;
     Suit Spades;
     Suit Clubs;
     public void Deck()
          Hearts = new Suit("Hearts");
          Diamonds = new Suit("Diamonds");
          Spades = new Suit("Spades");
          Clubs = new Suit("Clubs");
     public Card DrawCard()
          System.out.println("Drawing card...");
          Random generator = new Random();
          Card card = null;
          System.out.println("Card variable inited");
          while (card == null)
               System.out.println("Bleep");
               switch (generator.nextInt(4))
                    case 0:
                         System.out.println("0");
                         return Hearts.getAvailableCard();
                    case 1:
                         System.out.println("1");
                         return Diamonds.getAvailableCard();
                    case 2:
                         System.out.println("2");
                         return Spades.getAvailableCard();
                    case 3:
                         System.out.println("3");
                         return Clubs.getAvailableCard();
                    default:
                         System.out.println("none");                    
          System.out.println("Exited while loop");
          return card;
import java.util.*;
public class Suit
     Card[] cards = new Card[13];
     public Suit(String suit_)
          cards[0] = new Card("Two", suit_);
          cards[1] = new Card("Three", suit_);
          cards[2] = new Card("Four", suit_);
          cards[3] = new Card("Five", suit_);
          cards[4] = new Card("Six", suit_);
          cards[5] = new Card("Seven", suit_);
          cards[6] = new Card("Eight", suit_);
          cards[7] = new Card("Nine", suit_);
          cards[8] = new Card("Ten", suit_);
          cards[9] = new Card("Jack", suit_);
          cards[10] = new Card("Queen", suit_);
          cards[11] = new Card("King", suit_);
          cards[12] = new Card("Ace", suit_);
     public Card getAvailableCard()
          System.out.println("Getting an available card...");
          Random generator = new Random();
          Card card = new Card();
          int randomNo = generator.nextInt(13);
          System.out.println(randomNo);
          if (cards[randomNo].isAvailable())
               return cards[randomNo];
          return card;
public class Card
     String strValue;
     String suitName;
     int value;
     int suit;
     boolean available = true;
     public Card()
          strValue = "Out";
          suitName = "cards";
     public Card(String strValue_, String suitName_)
          strValue = strValue_;
          suitName = suitName_;
     public String getTitle()
          String title = strValue + " of " + suitName;
          return title;
     public void setAvailable(boolean available_)
          available = available_;
     public boolean isAvailable()
          return available;
What the program is meant to do is create a deck of cards, then pick ten cards, randomly picking a suit and card in that suit. If the card has already been drawn ( not available ) then the DrawCard() method should repick a suit and card and try again. The program may be doing something differently to what I have said and may be a bit messy just because I have messed around with things trying to understand why I am getting the exception. This is the exception:
Exception in thread "main" java.lang.NullPointerException
at Deck.DrawCard(Deck.java:34)
at DeckOfCards.main(DeckOfCards.java:13)
The program doesn't even make it to the first line of the getAvailableCard() method in the Suit Class.
So all I am asking is can anyone see why I am getting the null pointer exception and what action could I take to fix it. Thankyou to anyone who has read this.

Answer 1

Figure out what's null.
Print out cards and then cards[randomNo].
If those aren't null, then you need to look more closely at the erorr message and put in print statements to find out what is.
Whatever turns out to be null, you'll need to trace back and figure out why.
If it's the array, and the array is a member variable, then you need to know that reference member variables are initilaized to null.
If the array isn't null (because you did cards = new Card[something]) but cards[randomNo] is null, then it's because you didn't do this: for (int ix = 0; ix < cards.length; ix++) {
    cards[ix] = new Card(...);
}