Finding & Returning Duplicates

[Snowdrift]

Hi, I'm having some problems while working on a programming assignment.

I am trying to create a method to 1) find out if there are any duplicate cards in the pack and 2) print out the duplicate card if there is one.

The following is the card class:-

/*
 * A class to model a playing card.
 */
public class Card {

	private int number;
	private String suit;

	/*
	 * Randomly creates a card numbered 1 to 13 (ace = 1!) and labelled "Hearts","Clubs","Diamonds" or "Spades".
	 */
	public Card() {
		double randomNum = Math.random() * 4.0;
		if (randomNum < 1.0)
			suit = "Hearts";
		else if (randomNum < 2.0)
			suit = "Clubs";
		else if (randomNum < 3.0)
			suit = "Diamonds";
		else
			suit = "Spades";
		randomNum = Math.random() * 13.0;
		number = (int) randomNum + 1;
	}
	/*
	 * Creates a card with specified number and suit
	 */
	public Card (int n, String s) {
		number = n;
		suit = s;
	}
	
	public int getNumber() {
		return number;
	}
	
	public String getSuit () {
		return suit;
	}

	/*
	 * Converts Card to String representation e.g. "Ace of Spades"
	 */
	public String cardString() {
		// System.out.println(number + " " + suit);
		String stringNum = "";
		switch (number) {
		case 1:
			stringNum = "Ace";
			break;
		case 2:
			stringNum = "Two";
			break;
		case 3:
			stringNum = "Three";
			break;
		case 4:
			stringNum = "Four";
			break;
		case 5:
			stringNum = "Five";
			break;
		case 6:
			stringNum = "Six";
			break;
		case 7:
			stringNum = "Seven";
			break;
		case 8:
			stringNum = "Eight";
			break;
		case 9:
			stringNum = "Nine";
			break;
		case 10:
			stringNum = "Ten";
			break;
		case 11:
			stringNum = "Jack";
			break;
		case 12:
			stringNum = "Queen";
			break;
		case 13:
			stringNum = "King";
			break;
		default:
			System.out.println("Error in Card - illegal number");
		}
		return stringNum + " of " + suit;
	}
}

And this is what I have so far, which isn't working.

	/*
	 * Return true if there is a duplicate card in the pack
	 */
	public boolean hasDuplicate() {
		
		
		 for (int index = 0; index < pack.size(); index++){
			 for(Card c: pack){
				 if(c.getNumber() && c.getSuit() == c[index].getNumber() && c[index].getSuit());
			 }
		 }
	    	
		 return true;
		 
	}



	/*
	 * Return any duplicate card, 'null otherwise
	 */
	public Card getDuplicate() {
		
		for(Card c: pack){
		if(c.hasDuplicate = true);{
			System.out.println(c.cardString);
		}
		}
		
	}

}

A sidenote is that I cannot change the Card class in any way as that was provided for us. Any help would be appreciated. Thanks.

[Junky]

which isn't working.

I wanted to drive my car this morning but it didn't start. So I rang the mechanic and told him it wasn't working. Surprise surprise he couldn't help me until I gave him more details.

[Snowdrift]

Sorry about that, knew I forgot something when I previewed my post. ^^; I've highlighted the areas where Eclipse is giving me the error.

	/*
	 * Return true if there is a duplicate card in the pack
	 */
	public boolean hasDuplicate() {
		
		
		 for (int index = 0; index < pack.size(); index++){
			 for(Card c: pack){
				 if(c.getNumber() && c.getSuit() == [COLOR="Red"]c[index][/COLOR].getNumber() && [COLOR="red"]c[index][/COLOR].getSuit());
			 }
		 }
	    	
		 return true;
		 
	}

Multiple markers at this line.
The type of the expression must be an array type but it resolved to Card.

	/*
	 * Return any duplicate card, 'null otherwise
	 */
	public Card getDuplicate() {
		
		for(Card c: pack){
		if(c.[COLOR="red"]hasDuplicate[/COLOR] = true);{
			System.out.println([COLOR="red"]c.cardString[/COLOR]);
		}
		}
		
	}

}

hasDuplicate cannot be resolved or is not a field.
cardString cannot be resolved or is not a field.

[Junky]

hasDuplicate and cardString are methods. What are you missing?

c.hasDuplicate = true

This is an assignment and not a comparison. Even better there is no need to do a comparison with booleans.

if(c.hasDuplicate = true);{

Study that line very carefully and see if you can find what is semantically wrong (if you fix the other problems mentioned above).

[Junky]

c[index].getNumber()

You are treating c as an array but what have you declared c has?

[Snowdrift]

c.hasDuplicate = true

This is an assignment and not a comparison. Even better there is no need to do a comparison with booleans.

So I don't need that statement at all...?

What I have now: -

	/*
	 * Return any duplicate card, 'null otherwise
	 */
	public Card getDuplicate() {
		
		for(Card c: pack){
		if([COLOR="Red"]c.hasDuplicate([/COLOR]) == true){
			System.out.println(c.cardString());
		}
		}
		
	}

}

The method hasDuplicate() is undefined for the type Card.

c[index].getNumber()

You are treating c as an array but what have you declared c has?

A variable? :S

[Junky]

So I don't need that statement at all...?

No what I mean is that it is pointless comparing booleans when they are booleans already.

boolean bool = true;
if(bool == true) {}
// same as
if(bool) {}

The method hasDuplicate() is undefined for the type Card.

Not sure about this. Make sure your spelling is correct and the method actually is in the Card class. Also try deleting the .class file(s) and compile again.

A variable? :S

Yes it is a variable but what type is it. Is it an array? No so why are you treating it like an array?

[Snowdrift]

Not sure about this. Make sure your spelling is correct and the method actually is in the Card class. Also try deleting the .class file(s) and compile again.

The hasDuplicate() is the method I am working on along with the getDuplicate() method. It's not in the Card class but in another class called Pack Cards which is the only class I am allowed to edit. Does this mean I can't call methods inside the same class?

Yes it is a variable but what type is it. Is it an array? No so why are you treating it like an array?

I thought to find duplicates you would need an array to hold one of the cards in the pack and then compare it with the rest of the pack to see if there's any matching ones. Is this not the correct way to do it? :confused:

[Junky]

It's not in the Card class but in another class called Pack Cards

So why are you trying to call that method on a Card object? It would seem you lack some basic understanding. You need to go back and read a textbook/your lecture notes/an online tutorial.

I thought to find duplicates you would need an array to hold one of the cards in the pack and then compare it with the rest of the pack

Sounds reasonable but c is a single Card object and not an array of Card objects. Once again you need to revise material already covered to get a better understanding.

[Snowdrift]

I will do that. However have you got any other solutions I could try out just now? Since the assignment is due tomorrow and I haven't gotten any closer to solving it....:(