Java的帮助！ 实现某个对象的二维数组，该对象具有多个私有数据类型和对象

Question

我正在尝试在Java中创建对象的2D数组。 Java中的此对象中包含几个私有变量和方法，但是不起作用。 有人可以告诉我原因，有办法解决这个问题吗？ 这是我不断尝试在2d对象中进行初始化和迭代的每一行代码的一种理解。

“ wumpusworld.WumpusWorldGame.main（WumpusWorldGame.java:50）的线程“ main”中的java.lang.NullPointerException异常Java结果：1”

这是我的主要课程：

public class WumpusWorldGame {

    class Agent {

        private boolean safe;
        private boolean stench;
        private boolean breeze;

        public Agent() {
            safe = false;
            stench = false;
            breeze = false;
        }

    }

    /**
     * @param args
     *            the command line arguments
     * @throws java.lang.Exception
     */
    public static void main(String [] args) {
        // WumpusFrame blah =new WumpusFrame();
        // blah.setVisible(true);

        Scanner input = new Scanner(System.in);

        int agentpts = 0;
        System.out.println("Welcome to Wumpus World!\n ******************************************** \n");

//ArrayList<ArrayList<WumpusWorld>> woah = new ArrayList<ArrayList<WumpusWorld>>();

        for (int i = 0 ; i < 5 ; i++) {

            WumpusWorldObject [] [] woah = new WumpusWorldObject [5] [5];

            System.out.println( "*********************************\n Please enter the exact coordinates of the wumpus (r and c).");
            int wumpusR = input.nextInt();
            int wumpusC = input.nextInt();

            woah[wumpusR][wumpusC].setPoints(-3000);
            woah[wumpusR][wumpusC].setWumpus();
            if ((wumpusR <= 5 || wumpusC <= 5) && (wumpusR >= 0 || wumpusC >= 0)) {
                woah[wumpusR][wumpusC].setStench();
            }
            if (wumpusC != 0) {
                woah[wumpusR][wumpusC - 1].getStench();
            }
            if (wumpusR != 0) {
                woah[wumpusR - 1][wumpusC].setStench();
            }
            if (wumpusC != 4) {
                woah[wumpusR][wumpusC + 1].setStench();
            }
            if (wumpusR != 4) {
                woah[wumpusR + 1][wumpusC].setStench();
            }

            System.out.println( "**************************************\n Please enter the exact coordinates of the Gold(r and c).");
            int goldR = input.nextInt();
            int goldC = input.nextInt();
            woah[goldR][goldC].setGold();
            System.out.println("***************************************\n How many pits would you like in your wumpus world?");
            int numPits = input.nextInt();
            for (int k = 0 ; k < numPits ; k++) {
                System.out.println("Enter the row location of the pit");
                int r = input.nextInt();
                System.out.println("Enter the column location of the pit");
                int c = input.nextInt();
                woah[r][c].setPit();
                if ((r <= 4 || c <= 4) && (r >= 0 || c >= 0)) {
                    woah[r][c].setBreeze();
                }
                if (c != 0) {
                    woah[r][c - 1].setBreeze();
                }
                if (r != 0) {
                    woah[r - 1][c].setBreeze();
                }
                if (c != 4) {
                    woah[r][c + 1].setBreeze();
                }
                if (r != 4) {
                    woah[r + 1][c].setBreeze();
                }
            }
            for (int x = 0 ; x < 4 ; x++) {
                int j = 0;
                while (j < 4) {
                    agentpts = agentpts + woah[x][j].getPoints();
                    Agent [] [] k = new Agent [4] [4];

                    if (woah[x][j].getWumpus() == true) {
                        agentpts = agentpts + woah[x][j].getPoints();
                        System.out.println("You just got ate by the wumpus!!! THE HORROR!! Your score is " + agentpts);
                    }
                    if (woah[x][j].getStench() == true) {
                        k[x][j].stench = true;
                        System.out.println("You smell something funny... smells like old person.");
                    }
                    if (woah[x][j].getBreeze() == true) {
                        k[x][j].breeze = true;
                        System.out.println("You hear a breeze. yeah");
                    }
                    if (woah[x][j].getPit() == true) {
                        agentpts = agentpts + woah[x][j].getPoints();
                        System.out.println("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH! you dumb bith, your dead now.");
                    }
                    // if breeze or stench, if breeze and stench, if nothing, etc then move.
                    k[x][j].safe = true;
                    // if(k[i][j].isSafe()!=true){

                    // } else { }
                }
            }
        }
    }
}

这是我要实现的类对象：

package wumpusworld;

/**
 *
 * @author Jacob
 */

public class WumpusWorldObject {
private boolean stench;
private boolean breeze;
private boolean pit;
private boolean wumpus;
private boolean gold;
private int points;
private boolean safe; 

public WumpusWorldObject(){   
}
    public boolean getPit() { 
      return pit;
    }

    public void setPit() {
        this.pit = true;
    }

    public boolean getWumpus() {
        return wumpus;
    }

    public void setWumpus() {
        this.wumpus = true;

    }

    public int getPoints() {
        return points;
    }

    public void setPoints(int points) {
        this.points = points;
    }
    public boolean getStench() {
        return stench;
    }

    public void setStench() {
        this.stench = true;
    }

    public boolean getBreeze() {
        return breeze;
    }

    public void setBreeze() {
        this.breeze = true;
    }

    public boolean getSafe() {
        return safe;
    }

    public void setSafe() {
        this.safe = true;
    }
    public void setGold(){
        this.gold=true;
    }
}

Answer 1

创建数组并不意味着它将自动用您的类的新实例填充。 原因有很多，例如

• 应该使用哪个构造函数
• 什么数据应该传递给此构造函数。

这种决定不应该由编译器来决定，而应该由程序员来决定，因此您需要显式调用构造函数。

创建数组后，对其进行迭代，并用类的新实例填充它。

for (int i=0; i<yourArray.length; i++)
    for (int j=0; j<yourArray[i].length; j++)
        yourArray[i][j] = new ...//here you should use constructor 

Answer 2

AClass[][] obj = new AClass[50][50];

还不够，您必须创建它们的实例，例如

obj[i][j] = new AClass(...);

在您的代码行中

woah[wumpusR][wumpusC].setPoints(-3000);

必须在之后

woah[wumpusR][wumpusC] = new WumpusWorldObject();

。