java - 在测试驱动程序中初始化ArrayList

我正在尝试初始化我的playingCard.java文件中定义的ArrayList的新实例：

import java.util.ArrayList;

public class PlayingCard
{

    public enum Value { Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten,
        Jack, Queen, King, Ace}

    public enum Suit { Spades, Diamonds, Hearts, Clubs }

    private final Value value;

    private final Suit suit;

    /**
    * Constructs a card with specified initial value and suit
    * @param value
    * @param suit
    */

    public PlayingCard(Value value, Suit suit)
    {
        this.value = value;
        this.suit = suit;
    }

    /**
     * Retrieves the value of a card
     * @return value
     */

    public Value getValue()
    {
        return value;
    }

    /**
     * Retrieves the suit of the card
     * @return suit
     */

    public Suit getSuit()
    {
    return suit;
    }

    /**
    * Custom toString
    *@return value and suit as a string.
    */

    @Override
    public String toString()
    {
        return "PlayingCard[value=" + value + ", suit=" + suit + "]";
    }

    /**
     * Format method to print out the value and suit of a card.
     * @return value and suit as a string.
     */

    public String format()
    {
        return value + " of " + suit + ", ";
    }

    /*private static final List<PlayingCard> deck = new ArrayList<PlayingCard>();

    // Initialize deck
    static
    {
        for (Suit suit : Suit.values())
        {
            for (Value value : Value.values())
            {
                 deck.add(new PlayingCard(value, suit));
            }
        }
    }*/
}

如果最后12行左右没有注释掉，则代码没有问题。但是我想在一个单独的测试驱动程序中初始化卡座，并在复制代码时收到2个错误。
测试驱动程序当前如下所示：

import java.util.ArrayList;

public class PlayingCardTester
{
public static void main (String[] args)
{
    static  List<PlayingCard> deck =
        new ArrayList<PlayingCard>();

    // Initialize deck
    static
    {
        //for ea PlayingCard.Suit suit in PlayingCard.Suit.values()
        for (PlayingCard.Suit suit : PlayingCard.Suit.values())
        {
            for (PlayingCard.Value value : PlayingCard.Value.values())
            {
                deck.add(new PlayingCard(value, suit));
            }
        }

    }
}
}

我在测试驱动程序的第14行出现错误

static  List<PlayingCard> deck = new ArrayList<PlayingCard>();

说这是非法表达。我尝试在语句前使用不同的关键字，并且错误保持不变。
第二个错误是最后一个括号，它说“ null”。
我对使用枚举不熟悉，所以它看起来很简单，我已经忽略了...

最佳答案

您不需要静态方法中的static声明。

List<PlayingCard> deck = new ArrayList<PlayingCard>();

另外，由于您已经处于静态上下文中，因此无需Static Block。



参考文献：


Static Initialization Blocks