CODEWITHSUNDEEP
javarandom
NerdsRaisedHand
NerdsRaisedHand

Reputation: 331

Why null is returned instead of a value?

I have the following code, and am wondering why null is returned when I run the program and not the actual value? Any help would be appericated. 

import java.util.Random;


public class TestCard {

    public static String[] possCards = new String[]{"2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K", "A"};
    public static String[] possSuits = new String[]{"C", "S", "H", "D"};
    public static Random rand = new Random();
    static String value;

    public static void main(String[] args) {
            System.out.println(getcard());
    }


    public static void card() {
        String card = possCards[rand.nextInt(possCards.length)];
        String suit = possSuits[rand.nextInt(possSuits.length)];

       value = card + suit;
    }
    public static String getcard(){
        return value;
    }


}

Upvotes: 3

Views: 96

Answers (6)

vandale
vandale

Reputation: 3650

you could also have a static block of code in your TestCard that will initialize the value for you:

static{
    card();
}

so you know value to be non null

Upvotes: 0

Prabhakaran Ramaswamy
Prabhakaran Ramaswamy

Reputation: 26094

Before calling the getcard() you need to call card() to preparing your calculations.

Your code need to look like below.

public static void main(String[] args) {
        card();
        System.out.println(getcard());
}

Upvotes: 0

Sage
Sage

Reputation: 15408

Check the following portion of your code:

    public static void main(String[] args) {
        System.out.println(getcard()); // printing getCard(), 
                                      //but card() isn't called before it!!
}


public static void card() {
    String card = possCards[rand.nextInt(possCards.length)];
    String suit = possSuits[rand.nextInt(possSuits.length)];

   value = card + suit; // assigning value in card() 
                        //but this function needs to get executed
}

Upvotes: 1

HasanAboShally
HasanAboShally

Reputation: 18675

You should call the card() function:

public static void main(String[] args) {
        card();
        System.out.println(getcard());
}

Upvotes: 0

Josh
Josh

Reputation: 1553

You're calling getcard() but never calling card(), so value is never set.

Upvotes: 1

Hovercraft Full Of Eels
Hovercraft Full Of Eels

Reputation: 285403

Because null is the value held by value at the time the program is run.

Why should it be any different if you don't call any of the methods that give value a reference, such as card(), before calling getCard()?

Key thing here is to try to walk through your code mentally step wise to see what it does. Either that or step through your code with a debugger.

Upvotes: 5

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