Question

I’m experimenting with Java arrays. What I want to do is count the occurrences of an array string element. For example:

Clubs - 8 
Clubs - Ace 
Clubs - Jack
Hearts - 9 
Spades - 3
Hearts - 6

Number of occurrences:

Clubs - 3
Hearts - 2
Spades - 1
Diamonds - 0

So far I only have coded this:

public class CardGame {
public static void main(String[] args){

     String[] suit = { "Clubs", "Hearts", "Diamonds", "Spades" };
     String[] deck = { "2", "3", "4", "5", "6", "7", "8", "9", "10",
                        "Jack", "Queen", "King", "Aces" };

     for( int a = 0; a < 7; a++ ){
     int i = (int) ( Math.random() * suit.length );
     int j = (int) ( Math.random() * deck.length );
         //System.out.println( "Suit " + suit[i] + " Deck " + deck[j] );
     System.out.println( suit[(int) (Math.random() * suit.length)]
             + " : " + deck[(int) (Math.random() * deck.length)]);
     }
            System.out.println();

  }
}

Give me some ideas on how to accomplish this. Thanks.

NOTE: This is not a homework. I’m just trying to give myself some exercises regarding arrays.

Answer 1

I believe you have missunderstood the answer to your previous question. The idea is to use the values of i and j in the cycle, not to generate them twice. Here is a working example. I am not using hash map because you know the suits and their count aforehand so just an array is enough:

public class Main {
    public static void main(String[] args){

         String[] suit = { "Clubs", "Hearts", "Diamonds", "Spades" };
         String[] deck = { "2", "3", "4", "5", "6", "7", "8", "9", "10",
                            "Jack", "Queen", "King", "Aces" };
         int counts[] = new int[4];
         for( int a = 0; a < 7; a++ ){
         int i = (int) ( Math.random() * suit.length );
         int j = (int) ( Math.random() * deck.length );
             //System.out.println( "Suit " + suit[i] + " Deck " + deck[j] );
         System.out.println( suit[i] + " : " + deck[j]);
         counts[i]++;
         }
                System.out.println();
         for (int i =0;i<4;++i){
            System.out.println(suit[i] + " : " + counts[i]);
         }

      }
    }

You can see the code on ideone.