Thread: NullPointerException in Poker's program

Hi, working on a poker program(isn't everybody?) After searching for hours on the web I'm hoping someone here can help me. Here is the problematic snippet below.

// this part works fine
for (Player player : players){
            player = new Player();
            player.pocketCard1 = new Card(deck.deal());
            System.out.print(player.pocketCard1.toString() + " ");
            player.pocketCard2 = new Card(deck.deal());
            System.out.print(player.pocketCard2.toString() + " ");
        }
 
// this part throws a null pointer exception
        System.out.print(players[0].pocketCard1.toString() + " ");

It seems like the assignments I made to pocketCard1 simply disappear when the for loop ends. Can I not use a for loop to set data members? The second piece of code does exactly the same thing as the first.
I'm pulling my hair out here.
-dean_martin

Hello dean_martin and welcome to the forums

Could you please attach all of the code so I can compile it and see the error for myself?

Ok here is everything:

edit: I'm using NetBeans 6.5.1

public enum Suit {
   DIAMONDS,
   CLUBS,
   HEARTS,
   SPADES
 
}
 
public enum Rank {
    DEUCE, THREE, FOUR, FIVE, SIX, SEVEN,
    EIGHT, NINE, TEN, JACK, QUEEN, KING, ACE
}
 
public class Card{
    Rank rank;
    Suit suit;
 
    public Card(){}
 
    public Card(Card card) {
        this.rank = card.rank;
        this.suit = card.suit;
    }
 
    public Card(Rank rank, Suit suit) {
        this.rank = rank;
        this.suit = suit;
    }
 
    public Suit getSuit() {
        return suit;
    }
 
    public Rank getRank() {
        return rank;
    }
 
    @Override
    public String toString() {
        return rank + " of " + suit;
    }
}
 
public class Deck{
    Card[] cards = new Card[52];
    int index;
 
    public Deck() {
        index = 0;
        int i = 0;
        for (Suit suit : Suit.values()) {
            for (Rank rank : Rank.values()) {
                cards[i++] = new Card(rank, suit);
            }
        }
    }
 
    @Override
    public String toString(){
        String allCards = "";
        for (Card card : cards){
            allCards += card.toString() + "\n";
        }
        return allCards;
    }
 
    public void shuffle(){
        for (int i = 0; i < this.cards.length; i++){
            int randomIndex = (int) (Math.random() * this.cards.length);
            Card current = this.cards[i];            
            this.cards[i] = this.cards[randomIndex];
            this.cards[randomIndex] = current;
        }
    }    
 
    public Card deal(){
        return this.cards[index++];
    }
}
 
public class Player {
    String name;
    int bankroll;
    int chipstack;
    Card pocketCard1;
    Card pocketCard2;
    String handRank;
 
    public Player(){
    }
 
    public void setPocketCards(Card card1, Card card2){
        pocketCard1 = card1;
        pocketCard2 = card2;
    }
}
 
public class Main{
 
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {        
        Deck deck = new Deck();
        deck.shuffle();
 
        int numberOfPlayers = 2;
        Player[] players = new Player[numberOfPlayers];
        for (Player player : players){
            player = new Player();
            player.pocketCard1 = new Card(deck.deal());
            System.out.print(player.pocketCard1.toString() + " ");
            player.pocketCard2 = new Card(deck.deal());
            System.out.print(player.pocketCard2.toString() + " ");
        }
        System.out.print(players[0].pocketCard1.toString() + " ");
 
//        for (Player player : players){
//            System.out.println("" +
//            player.pocketCard1.toString() +
//            player.pocketCard2.toString());
//        }
 
        Card[] communityCards = new Card[5];
        for (Card card : communityCards){
            card = new Card(deck.deal());
 
//        for (Card card : communityCards){
//            System.out.println(" " + card.toString());
        }
 
 
    }
 
}

Thanks for that dean,

I can see the exception. I will look into it now..

Dean, if this wasn't generating an exception, what is your expected output for:

System.out.print(players[0].pocketCard1.toString() + " ");

?

Hello dean,

The enhanced for loop is something that is reasonably new to myself. I have always used the regular for loop to print array data in the past. This will not cause any performance issues so there is no reason not to use regular for loops but like you say, its best practise to keep up with coding standards.

players[0] is being returned as null. I'm having a play with it now.

You will have to excuse my slow replies. I am at work so doing 10000 things at once

Ah OK yes that makes sense. Learning new things every day!

I'm glad you have resolved this. Thank you for marking your thread as solved