Question

我的程序有问题。

package game;

    import java.util.Random;
    import javax.swing.ImageIcon;

    public class deck {

     private Card deckOfCards[];
     private final int number_cards = 52;
     private Random various;
     private int currentCard;
     private int actualCard;
     public ImageIcon CardImage;

     public deck() {
      int value[] = { 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 10, 11 };

      ImageIcon[] image = {
        new ImageIcon("/root/Desktop/as.jpg"),
        new ImageIcon("/root/Desktop/as.jpg"),
        new ImageIcon("/root/Desktop/as.jpg"),
        new ImageIcon("/root/Desktop/as.jpg"),
        new ImageIcon("/root/Desktop/as.jpg"),
        new ImageIcon("/root/Desktop/as.jpg"),
        new ImageIcon("/root/Desktop/as.jpg"),
        new ImageIcon("/root/Desktop/as.jpg"),
        new ImageIcon("/root/Desktop/as.jpg"),
        new ImageIcon("/root/Desktop/as.jpg"),
        new ImageIcon("/root/Desktop/as.jpg"),
        new ImageIcon("/root/Desktop/as.jpg"),
        new ImageIcon("/root/Desktop/as.jpg"),
      };

      currentCard = 0;
      deckOfCards = new Card[number_cards];
      various = new Random();

      for (int count = 0; count < deckOfCards.length; count++) {
       deckOfCards[count] = new Card(Rank.values()[count % 13].toString(),Suit.values()[count / 13].toString(), value[count % 13], image[count % 13]);
      }
     }

     public void shuffle() {
      currentCard = 0;
      for (int first = 0; first < deckOfCards.length; first++) {
       int second = various.nextInt(number_cards);
       Card temp = deckOfCards[first];
       deckOfCards[first] = deckOfCards[second];
       deckOfCards[second] = temp;
      }
     }

     public Card giveCard() {
      if (currentCard < deckOfCards.length)
       return deckOfCards[currentCard++];
      else
       System.out.println("No more Cards.");
      return null;
     }

     public int totalValue() {
      int cardValue = (deckOfCards[actualCard].toInt());
      return cardValue;
     }

     public ImageIcon getImage() {
      return CardImage;
     }
    }

    package game;

    import java.awt.Image;

    import javax.swing.ImageIcon;

    public class Card {
     private final String faceCard;
     private final String suit;
     private final int number;
     public ImageIcon image;

     Card(String faceCard, String suit, int number_, ImageIcon image) {
      this.faceCard = faceCard;
      this.suit = suit;
      this.number = number_;
      this.image = image;
     }

     public String toString() {
      return faceCard + " of " + suit + "\n" + "Value of card: " + number;
     }

     public int toInt() {
      return number;
     }

     public void setImage(ImageIcon image) {
      this.image = image;
     }

     public ImageIcon getImage() {
      return image;
     }
    }

//swing part
     ImageIcon pic = new ImageIcon(myDeckOfCards.getImage());

  panel2.add(lab1);
  panel2.add(new JLabel(pic));
  panel2.add(card1);
  panel2.add(pn1);
  panel2.add(btn1);

Answer 1

NullPointerException意味着某些内容未初始化。你指的是不存在的东西。检查堆栈跟踪。通常会有一个引发异常的行号。这可能会给你一些提示。

Answer 2

看起来你正试图从myDeckOfCards获取图像，当它不存在时。您是否已声明并初始化myDeckOfCards实例？

为什么我的代码不在JPanel中显示图像？

2 个答案: