A problem with using an array

[Czuks]

Hi! I'm both new here and to java. I was following the java tutorial somewhere and it asked me to practice what I've learned already by writing a class representing a deck of cards. I had a class for single cards written before already. It looks like this:

package create;

public class Deck extends Card {
	
	private Card[] singleCard = new Card[52];
	
	
	public Deck() {
		
		
		char suit1 = 'X';
		String rank1 = "X";
		int counter = 0;
		
		for(int i = 0 ; i < 14 ; i++){
			
			/* some switches to assign correct suit/card rank  go here */


			
			singleCard[counter].modifyCard(suit1, rank1);	/* HERE */
			counter++;
			}
			
		
		}
	
	}
	
	/****************************************/
	
	public void printSingleCard(int cardNo) {
		System.out.printf(this.singleCard[cardNo].suit+" "+this.singleCard[cardNo].rank + "\n");
	}
	
}

But every time I tun it it says there's an error in the line there I put /*HERE*/ comment.
Could anyone help me with this one? What did I do wrong?
Thanks!

[KevinWorkman]

What is the exact error?

When do you initialize each index of the array?

[Czuks]

So I have to initialize every single index of the array, yes? How and where can I do it then?

The Error is

Exception in thread "main" java.lang.NullPointerException
at create.Deck.<init>(Deck.java:40)
at create.CreateObjectDemo.main(CreateObjectDemo.java :14)

[KevinWorkman]

Yep, when you initialize an array, each index contains the default value of the type contained by the array. For things like ints, that's zero. For Objects, however, that's null.

[Czuks]

That solved it! Thanks!

[Tolls]

Just a comment.
When you are extending a class you are essentially saying that the <child class> is-a <parent class>.
In your code above you are saying a Deck is-a Card.