独立程序中的公共变量

Question

I'm writing a small Java program that randomly deals out playing cards, then displays them on screen in a window.

Since I'm using NetBeans, the GUI was started for me, and I've been writing my methods for randomly choosing cards, setting up an array to store whether or not a card has already been dealt, etc., all in the same class NetBeans set up for me when it built the JFrame.

I'd like to move all my non-GUI code into its own Class, and then just pass data back to the GUI class as needed to display the cards, but I'm not sure of the best way to share data between the two classes.

I know about set/get methods and I know I could make public class-level variables, but everything I've been reading tells me to avoid both as much as possible.

Right now I have a method that generates an int between 1 and 52 for each card dealt. 1 = Ace of spades, 2= 2 of spades, etc. Once the GUI has that number, it can display the appropriate card in the appropriate place on the screen (or at least it will be able to once I've coded the GUI side of things). If I'm looking to pass that integer value to the GUI class, then display a specific card on the screen based on that value, how should I do it?

Seems to me a public variable would make this easy, as would a simple get method...but in the interest of avoiding those options is there another way?

I can provide code snippets if that helps.

Answer 1

Here's one way you could start to implement this idea using OO concepts.

Make a Card class to represent a card.

public class Card {
    // FIELDS
    // card name
    private final String name;
    // card value (number)
    private final int value;
    // another arbitrary value to demonstrate setter
    private Object arbitraryValue;


    public Card(String name, String value) {
        this.name = name;
        this.value = value;
    }

    public String getName() {
        return this.name;
    }

    public int getValue() {
        return this.value;
    }

    public Object getArbitraryValue() {
        return this.arbitraryValue;
    }

    public void setArbitraryValue(Object arbitraryValue) {
        this.arbitraryValue = arbitraryValue;
    }
}

Create a CardManager class to hold methods that pertain to handling cards (eg utility methods and card data storage)

public class CardManager() {
    private List<Card> cards = new ArrayList<Card>();

    public void addCard(Card card) {
        this.cards.add(card);
    }

    // and so on...your methods here.
}

Finally, create a class for your GUI ( CardGUI ) management and make use of the other classes to manage it.

You can do so like this:

public class CardGUI() {
    public static void main(String[] args) {
        // create your GUI and put your logic here...
        // also use your other classes, perhaps like so.
        Card card = new Card("One", 1);
        CardManager cardManager = new CardManager();
        cardManager.addCard(card);

        // From there you can manage your cards through other classes.
}

Hope this helps / demonstrates how to share data between classes following standards.

Edit: To answer your question on exactly how you would get the value, then see the above Card class. You would simple create a new card ( Card card = new Card("name", intval); ), then you would use the method Card#getValue() to get that value and display it in the GUI.