Thread: Trying to wrap my head around Objects with this simple Card Game!

Hey, i am a bit of a noob. I'm trying to get my head around Objects and how they work.

I was going over a Card game tutorial and i'm a bit confused on what is going on in some of these examples.

package javacards;
 
public class Card {
	private int rank, suit;
	//Declaring the Array of Cards.
	private static String[] suits = { "hearts", "spades", "diamonds", "clubs" };
	private static String[] ranks = { "Ace", "2", "3", "4", "5", "6", "7", "8",
			"9", "10", "Jack", "Queen", "King" };
 
 
	Card(int suit, int rank) {
		this.rank = rank;
		this.suit = suit;
	}
 
	public @Override String toString() {
		return ranks[rank] + " of " + suits[suit];
	}
 
	public int getRank() {
		switch(rank) {
		case 0: return 0;
		case 1: return 1;
		case 2: return 2;
		case 3: return 3;
		case 4: return 4;
		case 5: return 5;
		case 6: return 6;
		case 7: return 7;
		case 8: return 8;
		case 9: return 9;
		case 10: return 10;
		case 11: return 10;
		case 12: return 10;
		default: return 0;
		}
 
 
	}
 
	public int getSuit() {
		return suit;
	}
 
}

package javacards;
 
import java.util.Random;
 
public class Deck {
	private Card[] cards;
	int i;
 
	Deck()
	{
		i=51;
		cards = new Card[52];
		int x=0;
		for (int a=0; a<=3; a++)
		{
			for (int b=0; b<=12; b++)
			 {
			   cards[x] = new Card(a,b);
			   x++;
			 }
		}
	}
 
	public Card drawFromDeck()
	{
		Random generator = new Random();
		int index=0;
 
		do {
			index = generator.nextInt( 52 );
		} while (cards[index] == null);
 
		i--;
		Card temp = cards[index];
		cards[index]= null;
		return temp;
	}
 
	public int getTotalCards()
	{
		return i;
	}
}

package javacards;
 
public class Main {
 
	public static void main(String[] args)
	{
		Deck deck = new Deck();
		Card C;
 
		System.out.println( deck.getTotalCards() );	
 
	   while (deck.getTotalCards()!= 0 )
	   {
		   C = deck.drawFromDeck();
		   System.out.println( C.toString() );
	   }
	}
 
}

Okay, so i just have a few questions;

1. Once i have outputted a cards name, how do i assign it a integer value? So for a 8 of clubs to = 8? I tried to use the switch statements.

2. Since this is a typical Blackjack game, working with an Ace will be tricky, since it can also be a 1 or 11. Should i declare that value in the object somehow? or worry about declaring its value when the users is promoted to take the 1 or 11.'

3. in main, i don't under stand what doing on when they wrote 'Card C;' does that mean Card is now a type with the value C, or C has a value of card?
Is this the same way Strings work? since im starting to think Strings are an object and not an actual value?

Sorry if i'm not clear, since im just confused as hell :S

1. As objects, instances of the Card class already have a value or should have. The basic Card attributes or characteristics are stored in the object's instance variables, including its value

Personally, I think the Card class example you posted is a bad example, or at least it's not a very general example. A Card object should know about its own suit, value, face graphic, and name and nothing about any other card object. Much of the code in the Card class you posted should be in the Deck class.

2. The rules of the game dictate whether the value of an Ace is 1 or 11 just as there are special rules about Jacks IN THAT GAME. That logic belongs in the game, not in the Card object. The Card object doesn't care or know the rules of game being played. The simpler the Card object can be, the better.

3. You have general confusion about Object Oriented Programming that is not unusual. It takes a while for the light to come on. Classes, including String, define 'types' in Java. Card is a type. String is a type. int is a primitive data type. The statement

Card card;

is a declaration that specifies the variable 'card' to be of type Card. After card is initialized with

card = new Card();

card becomes a Card object.

Type and class names in Java begin with capital letters, variables and method names begin with lowercase letters. The declaration:

Card C;

violates Java's naming conventions and just because of that causes confusion.

Keep plugging away, ask questions when you get confused, and eventually it'll click. Don't give up.

Thanks dude, that helps a lot but i'm still stuck on Question 1.

I cant work out how to assign the value or even add the values together. Since i need to draw 2 cards and add the values together.

Use Card's getRank() method to get the card objects' values:

in cardSum = card1.getRank() + card2.getRank();

card1 and card2 are card objects, and in your program are probably kept in a Deck, so your statement will look different.

Thanks for the prompt reply.

I feel a bit stupid asking that question after looking at the answer, i should have known :/
Thanks again!

Go easy on yourself. The answer was likely hidden by your general confusion over objects. If you keep at it, SOON the fog will lift.