为什么从对象获取信息时会出现 StackOverflowError？

Question

您好，我目前正在尝试用 Java 创建一个宫殿游戏。 我参加了单独学习的课程，但从未真正学会如何处理堆栈溢出错误。 我在互联网上找到的所有问题都没有。 目前在变量AllCards aceClover = new AllCards(); 它说有一个 StackOverFlowError，我不知道为什么。

package MainClasses;
import java.awt.*;
import java.io.*;
import javax.imageio.ImageIO;
import java.util.Random;
public class AllCards {
    private Image cardImg = null;// to set image
    private String cardImgURL = ""; // get image location
    private int cardOrder = 0; // Card order in a hierarchy
    public boolean ruleAffect = false;  // if rules is changed can affect
    private boolean cardPower = false; // is the card a special card?
    private int cardPowerNumber = 0; // which are the powers 1.Go again 2.Clear 3.mirror 4.Put card lower 5.Pick up deck unless have a copy
    AllCards aceClover = new AllCards(); // declared the Clover Ace
    AllCards twoClover = new AllCards();
    AllCards threeClover = new AllCards();
    AllCards fourClover = new AllCards();
    AllCards fiveClover = new AllCards();
    AllCards sixClover = new AllCards();
    AllCards sevenClover = new AllCards();
    AllCards eightClover = new AllCards();
    AllCards nineClover = new AllCards();
    AllCards tenClover = new AllCards();
    AllCards jackClover = new AllCards();
    AllCards queenClover = new AllCards();
    AllCards kingClover = new AllCards();
    public Image imageExtract;
    public String cardImgUrlExtractor;
    public int cardOrderExtract;
    public boolean ruleAffectExtract;
    public boolean cardPowerExtractor;
    public int cardPowerNumberExtractor;

    public AllCards() {


        aceClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile000.png"; // clover ace url
        if(aceClover.ruleAffect == false) {
            aceClover.cardOrder = 1;
        }else {
            aceClover.cardOrder = 14;
        }

        try {

            aceClover.cardImg = ImageIO.read(new File(aceClover.cardImgURL));

        }catch(Exception e) {

            System.out.println("Could't loud the Image! Error : "+e.getMessage());

        }

        twoClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile001.png";
        twoClover.cardOrder = 14;
        twoClover.cardPower = true;
        twoClover.cardPowerNumber = 2;
        try {
            twoClover.cardImg = ImageIO.read(new File(twoClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        threeClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile002.png";
        threeClover.cardOrder = 15;
        threeClover.cardPower = true;
        if(threeClover.ruleAffect == false) {
            threeClover.cardPowerNumber = 14;
        }else {
            threeClover.cardPowerNumber = 3;
        }

        try {
            threeClover.cardImg = ImageIO.read(new File(threeClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        fourClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile003.png";
        fourClover.cardOrder = 4;
        try {
            fourClover.cardImg = ImageIO.read(new File(fourClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        fiveClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile004.png";
        fiveClover.cardOrder = 5;
        try {
            fiveClover.cardImg = ImageIO.read(new File(fiveClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        sixClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile005.png";
        sixClover.cardOrder = 6;
        try {
            sixClover.cardImg = ImageIO.read(new File(sixClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        sevenClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile006.png";
        sevenClover.cardOrder = 14;
        sevenClover.cardPower = true;
        sevenClover.cardPowerNumber = 4;
        try {
            sevenClover.cardImg = ImageIO.read(new File(sevenClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        eightClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile007.png";
        eightClover.cardOrder = 8;
        try {
            eightClover.cardImg = ImageIO.read(new File(eightClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        nineClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile008.png";
        nineClover.cardOrder = 9;
        try {
            nineClover.cardImg = ImageIO.read(new File(nineClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        tenClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile009.png";
        tenClover.cardOrder = 15;
        tenClover.cardPower = true;
        tenClover.cardPowerNumber = 14;
        tenClover.ruleAffect = true;
        try {
            tenClover.cardImg = ImageIO.read(new File(tenClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        jackClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile010.png";
        jackClover.cardOrder = 11;
        try {
            jackClover.cardImg = ImageIO.read(new File(jackClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        queenClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile011.png";
        queenClover.cardOrder = 12;
        try {
            queenClover.cardImg = ImageIO.read(new File(queenClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        kingClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile012.png";
        kingClover.cardOrder = 13;
        try {
            kingClover.cardImg = ImageIO.read(new File(kingClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }
    }
    public void setVariables(AllCards x) {
        imageExtract = x.cardImg;
        cardImgUrlExtractor = x.cardImgURL;
        cardOrderExtract = x.cardOrder;
        ruleAffectExtract = x.ruleAffect;
        cardPowerNumberExtractor = x.cardPowerNumber;
        cardPowerExtractor = x.cardPower;
    }
    public void randomizer() {
        Random rand = new Random();
        int rand_int1 = rand.nextInt(15-1)+1;
        System.out.print(rand_int1);
        if (rand_int1 == 1) {
            setVariables(aceClover);

        }else if (rand_int1 == 2) {
            setVariables(twoClover);
        }else if (rand_int1 == 3) {
            setVariables(threeClover);
        }else if (rand_int1 == 4) {
            setVariables(fourClover);
        }else if (rand_int1 == 5) {
            setVariables(fiveClover);   
        }else if (rand_int1 == 6) {
            setVariables(sixClover);
        }else if (rand_int1 == 7) {
            setVariables(sevenClover);
        }else if (rand_int1 == 8) {
            setVariables(eightClover);
        }else if (rand_int1 == 9) {
            setVariables(nineClover);
        }else if (rand_int1 == 10) {
            setVariables(tenClover);
        }else if (rand_int1 == 11) {
            setVariables(jackClover);
        }else if (rand_int1 == 12) {
            setVariables(queenClover);
        }else if (rand_int1 == 13) {
            setVariables(kingClover);
        }else {
            System.out.println("Couldn't return any Cards!");
        }
    }
}

我想在这个类中做的是用某些变量创建一个对象。 然后所有这些变量都被分配了一个值，但是一旦它们分配了一个值，我想要一个函数来获取一个随机整数来选择某个对象将信息发送到另一个类，然后在屏幕上显示它。

package MainClasses;
import java.awt.*;
import java.io.*;
import java.util.Random;

import javax.imageio.ImageIO;

public class DrawBoard extends Component{
    AllCards accessor = new AllCards();
    public void paint(Graphics g) { // function to draw onto the window
    Graphics2D g1 = (Graphics2D)g; // the component being used to access and write to the window
    g1.clearRect(0, 0, getWidth(), getHeight()); // clears rectangle every frame
    g1.setBackground(Color.green); // sets background color
    accessor.randomizer();
    g1.drawImage(accessor.imageExtract, 100, 100, null);
    }   
}

这是我用来从对象中提取信息的函数。 我不是 100% 确定它有效，但从以前的版本来看，它显示得很好。

package MainClasses;
import java.awt.Color;

import javax.swing.*;
public class Main extends JFrame{

    public static void main(String[] args) {
        JFrame f = new JFrame("Palace");
        f.setSize(1920,1080);
        f.setResizable(false);
        f.setVisible(true);
        f.setDefaultCloseOperation(EXIT_ON_CLOSE);
        f.add(new DrawBoard());

    }

}

这是我用来创建 JFrame 的类，以防万一。

Answer 1

当尝试创建AllCards的新实例时，正在构造函数中创建AllCards另一个实例，而构造函数又将调用相同的构造函数，并再次尝试创建AllCards另一个实例，依此类推。 因此，对StackOverFlowError的无限循环。

建议的设计更改

1. 将“一张卡片”和“所有卡片”的概念分成两个独立的类，比如Card和当前的AllCards 。
2. 将所有单卡属性移动到Card类。 这将是一个简单的类，只有字段、getter 和 setter。
3. 让AllCards继续为每张卡片提供字段，但作为Card实例而不是早期的AllCards实例。

这是新的Card类（您需要生成 getter 和 setter 并使用它们。我已将字段更改为具有默认访问权限并使用它们。这不是推荐的方式。）

public class Card {
    Image cardImg = null;// to set image
    String cardImgURL = ""; // get image location
    int cardOrder = 0; // Card order in a hierarchy
    boolean ruleAffect = false;  // if rules is changed can affect
    boolean cardPower = false; // is the card a special card?
    int cardPowerNumber = 0; // which are the powers 1.Go again 2.Clear 3.mirror 4.Put card lower 5.Pick up deck unless have a copy
    public Image imageExtract;
    public String cardImgUrlExtractor;
    public int cardOrderExtract;
    public boolean ruleAffectExtract;
    public boolean cardPowerExtractor;
    public int cardPowerNumberExtractor;

    public Card() {}

}

以及更改后的AllCards类。

public class AllCards {
    private Image cardImg = null;// to set image
    private String cardImgURL = ""; // get image location
    private int cardOrder = 0; // Card order in a hierarchy
    public boolean ruleAffect = false;  // if rules is changed can affect
    private boolean cardPower = false; // is the card a special card?
    private int cardPowerNumber = 0; // which are the powers 1.Go again 2.Clear 3.mirror 4.Put card lower 5.Pick up deck unless have a copy
    Card aceClover = new Card(); // declared the Clover Ace
    Card twoClover = new Card();
    Card threeClover = new Card();
    Card fourClover = new Card();
    Card fiveClover = new Card();
    Card sixClover = new Card();
    Card sevenClover = new Card();
    Card eightClover = new Card();
    Card nineClover = new Card();
    Card tenClover = new Card();
    Card jackClover = new Card();
    Card queenClover = new Card();
    Card kingClover = new Card();
    public Image imageExtract;
    public String cardImgUrlExtractor;
    public int cardOrderExtract;
    public boolean ruleAffectExtract;
    public boolean cardPowerExtractor;
    public int cardPowerNumberExtractor;

    public AllCards() {



        aceClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile000.png"; // clover ace url
        if(aceClover.ruleAffect == false) {
            aceClover.cardOrder = 1;
        }else {
            aceClover.cardOrder = 14;
        }

        try {

            aceClover.cardImg = ImageIO.read(new File(aceClover.cardImgURL));

        }catch(Exception e) {

            System.out.println("Could't loud the Image! Error : "+e.getMessage());

        }

        twoClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile001.png";
        twoClover.cardOrder = 14;
        twoClover.cardPower = true;
        twoClover.cardPowerNumber = 2;
        try {
            twoClover.cardImg = ImageIO.read(new File(twoClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        threeClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile002.png";
        threeClover.cardOrder = 15;
        threeClover.cardPower = true;
        if(threeClover.ruleAffect == false) {
            threeClover.cardPowerNumber = 14;
        }else {
            threeClover.cardPowerNumber = 3;
        }

        try {
            threeClover.cardImg = ImageIO.read(new File(threeClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        fourClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile003.png";
        fourClover.cardOrder = 4;
        try {
            fourClover.cardImg = ImageIO.read(new File(fourClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        fiveClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile004.png";
        fiveClover.cardOrder = 5;
        try {
            fiveClover.cardImg = ImageIO.read(new File(fiveClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        sixClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile005.png";
        sixClover.cardOrder = 6;
        try {
            sixClover.cardImg = ImageIO.read(new File(sixClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        sevenClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile006.png";
        sevenClover.cardOrder = 14;
        sevenClover.cardPower = true;
        sevenClover.cardPowerNumber = 4;
        try {
            sevenClover.cardImg = ImageIO.read(new File(sevenClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        eightClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile007.png";
        eightClover.cardOrder = 8;
        try {
            eightClover.cardImg = ImageIO.read(new File(eightClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        nineClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile008.png";
        nineClover.cardOrder = 9;
        try {
            nineClover.cardImg = ImageIO.read(new File(nineClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        tenClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile009.png";
        tenClover.cardOrder = 15;
        tenClover.cardPower = true;
        tenClover.cardPowerNumber = 14;
        tenClover.ruleAffect = true;
        try {
            tenClover.cardImg = ImageIO.read(new File(tenClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        jackClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile010.png";
        jackClover.cardOrder = 11;
        try {
            jackClover.cardImg = ImageIO.read(new File(jackClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        queenClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile011.png";
        queenClover.cardOrder = 12;
        try {
            queenClover.cardImg = ImageIO.read(new File(queenClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

        kingClover.cardImgURL = "C:\\Users\\Jhosua\\eclipse-workspace\\Palace Game\\bin\\All Cards\\tile012.png";
        kingClover.cardOrder = 13;
        try {
            kingClover.cardImg = ImageIO.read(new File(kingClover.cardImgURL));
        }catch(Exception e) {
            System.out.println("Could't loud the Image! Error : "+e.getMessage());
        }

    }
    public void setVariables(Card x) {
        imageExtract = x.cardImg;
        cardImgUrlExtractor = x.cardImgURL;
        cardOrderExtract = x.cardOrder;
        ruleAffectExtract = x.ruleAffect;
        cardPowerNumberExtractor = x.cardPowerNumber;
        cardPowerExtractor = x.cardPower;
    }
    public void randomizer() {
        Random rand = new Random();
        int rand_int1 = rand.nextInt(15-1)+1;
        System.out.print(rand_int1);
        if (rand_int1 == 1) {
            setVariables(aceClover);

        }else if (rand_int1 == 2) {
            setVariables(twoClover);
        }else if (rand_int1 == 3) {
            setVariables(threeClover);
        }else if (rand_int1 == 4) {
            setVariables(fourClover);
        }else if (rand_int1 == 5) {
            setVariables(fiveClover);   
        }else if (rand_int1 == 6) {
            setVariables(sixClover);
        }else if (rand_int1 == 7) {
            setVariables(sevenClover);
        }else if (rand_int1 == 8) {
            setVariables(eightClover);
        }else if (rand_int1 == 9) {
            setVariables(nineClover);
        }else if (rand_int1 == 10) {
            setVariables(tenClover);
        }else if (rand_int1 == 11) {
            setVariables(jackClover);
        }else if (rand_int1 == 12) {
            setVariables(queenClover);
        }else if (rand_int1 == 13) {
            setVariables(kingClover);
        }else {
            System.out.println("Couldn't return any Cards!");
        }
    }
}