How would I create a new object from a class using a for loop in java?

Question

I have a class named Card and I have this for loop:

int i;
for (i = 0; i < 13; i++) {
    Card cardNameHere = new Card();
}

What I want to do is create new instances based on the for loop. So for example, I would like the names to be card1, card2, card3, etc. The number would come from the for loop.

I have tried this and it does not seem to work:

int i;
for (i = 0; i < 13; i++) {
    Card card[i] = new Card();
}

Can anyone tell me what I am doing wrong?

Thanks.

---

So I am using the solution from Hovercraft Full Of Eels, but I have another problem.

I am using cardList.add(new Card()); , and when I try to use Card(i) to set the name, java won't let me do it. Using it without i works fine, but how do I access it so I can call another method on it such as setId. I would like to call cardName.setId();

Answer 1

Create your array before the loop, and fill it inside the loop. Better to use an ArrayList though.

List<Card> cardList = new ArrayList<Card>();
for (i = 0; i < MAX_CARD; i++) {
  cardList.add(new Card());
  // or new Card(i) as the case may be
}

If you're filling a deck of cards, and you have your Suit and Rank enums nicely created, then:

List<Card> cardList = new ArrayList<Card>();
for (Suit suit: Suit.values()) {
  for (Rank rank: Rank.values()) { 
    cardList.add(new Card(suit, rank));
  }
}

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Edit
You state in comment:

So I am using cardList.add(new Card()); , and when I try to use Card(i) to set the name, java won't let me do it. Using it without i works fine, but how do I access it so I can call another method on it such as setId. I would like to call the cardName.setId();

Card(i) doesn't make sense as you can't treat the Card class as if it were a method -- again I'm not even sure what to make of it, what you're trying to do here. If you need to extract a Card from the ArrayList, you will need to call the get(...) method on the ArrayList, here called cardList . Better still would be to set the Card properties in its constructor as I show in my 2nd code snippet.

Answer 2

In Java, variable names have to be known at compile-time. Even in other languages like JavaScript, where that is not true, it is a good idea to not try to dynamically create variables at runtime.

This is exactly what arrays are meant to solve: when you have items of a known type, but unknown quanity at compile time. You need to declare the card as an array: Card[] cards

Card[] cards = new Card[13];
for (int i = 0; i < cards.length; i++) {
    cards[i] = new Card();
}

Notice I changed the for loop to loop through to cards.length, which is figured out at runtime, so that 13 does not have to be hard-coded in both places.