Question

我的java任务包括创建一个名为Qwixx的棋盘游戏。你掷骰子然后划掉游戏牌上的数字，那里有2行从2到12行，另外2行从12到2行。我的问题是创建访问器方法以获取每行的最后一个交叉编号。最后划掉的数字应该是游戏板右边最远的数字。这就是我对Player类的看法：

public class Player {
    private String[][] gameBoard = new String[4][11];
    private int lastCrossedOffR;

    //default constuctor 
    public Player() {
        lastCrossedOffR = 0;
        initializeGameboard();
    }

    //get method to obtain the last number that has been crossed off
    public int getLastCrossedOffR() {
        for(int j = 0; j<gameBoard[0].length;) {
            if (gameBoard[0][j] == "X") {
                if (j == 0)
                    lastCrossedOffR = 2;
                else if (j == 1)
                    lastCrossedOffR = 3;
                else if (j == 2)
                    lastCrossedOffR = 4;
                else if (j == 3)
                    lastCrossedOffR = 5;
                else if (j == 4)
                    lastCrossedOffR = 6;
                else if (j == 5)
                    lastCrossedOffR = 7;
                else if (j == 6)
                    lastCrossedOffR = 8;
                else if (j == 7)
                    lastCrossedOffR = 9;
                else if (j == 8)
                    lastCrossedOffR = 10;
                else if (j == 9)
                    lastCrossedOffR = 11;
                else if (j == 10)
                    lastCrossedOffR = 12;
            } else {
                j++;
            }
        }
        return lastCrossedOffR;
    }

    //method that initializes each row of the game board 
    public void initializeGameboard() {
        for (int i = 0; i<gameBoard.length; i++) {
            for (int j = 0; j<gameBoard[i].length; j++) {
                if (i==0 || i==1) {
                    if (j==0) {gameBoard[i][j] = "2";} 
                    else if (j==1) {gameBoard[i][j] = "3";} 
                    else if (j==2) {gameBoard[i][j] = "X";} //i placed random x's to 
                    else if (j==3) {gameBoard[i][j] = "5";} //test out the get 
                    else if (j==4) {gameBoard[i][j] = "6";} //method
                    else if (j==5) {gameBoard[i][j] = "7";} 
                    else if (j==6) {gameBoard[i][j] = "X";} 
                    else if (j==7) {gameBoard[i][j] = "X";} //in my case, what the
                    else if (j==8) {gameBoard[i][j] = "10";} //get method should 
                    else if (j==9) {gameBoard[i][j] = "11";} //return is: 9
                    else if (j==10) {gameBoard[i][j] = "12";}

                } else if (i==2 || i==3) {
                    if (j==0) {gameBoard[i][j] = "12";} 
                    else if (j==1) {gameBoard[i][j] = "11";} 
                    else if (j==2) {gameBoard[i][j] = "10";} 
                    else if (j==3) {gameBoard[i][j] = "9";} 
                    else if (j==4) {gameBoard[i][j] = "8";} 
                    else if (j==5) {gameBoard[i][j] = "7";} 
                    else if (j==6) {gameBoard[i][j] = "6";} 
                    else if (j==7) {gameBoard[i][j] = "5";} 
                    else if (j==8) {gameBoard[i][j] = "4";} 
                    else if (j==9) {gameBoard[i][j] = "3";} 
                    else if (j==10) {gameBoard[i][j] = "2";}
                }
            }
        }
    }

这是我的Driver类：

public class Driver {

    public static void main(String[] args) {
        Player obj1 = new Player();
        obj1.printGameboard(); //assume this method is already created in the Player class
        System.out.print("The last crossed off number for the Red row is: " + obj1.getLastCrossedOffR());
    }
}

这是我运行代码时需要显示的内容：

player's gameboard: 
           Red: 1 2 3 X 5 6 7 X X 10 11 12
        Yellow: 1 2 3 4 5 6 7 8 9 10 11 12
         Green: 12 11 10 9 8 7 6 5 4 3 2 1
          Blue: 12 11 10 9 8 7 6 5 4 3 2 1

The last crossed off number for the Red row is: 9

请帮我弄清楚如何修复getLastCrossedOffR()方法！提前谢谢！

Answer 1

您的问题是，您要将String与==而不是equals进行比较，请改用：

public int getLastCrossedOffR() {
    for(int j = 0; j < gameBoard[0].length;) {
        // was previously `gameBoard[0][j] == "X"`
        if ("X".equals(gameBoard[0][j])) {
            // ...

==运算符比较变量中字面的内容。对于像int这样的原语，这很好，因为它实际上存储了原始值。但是在Object s String s的情况下，它存储了对象引用。

想象一下，"X"是String，其中引用Object #1和gameBoard[0][0]存储了String引用Object #2。

调用"X" == gameBoard[0][0]就像调用Object #1 == Object #2一样，这是假的。（除非您已将Object #1存储在gameBoard[0][0]）

但是调用"X".equals(gameBoard[0][0])就像调用Object #1.equals(Object #2)进入equals Object #1函数{aka String.equals(Object o)）并比较值这两个String而不是比较他们的参考文献。

经验法则是==仅适用于基元（int，float，long，double，{{1} }，short，byte，char），但对其他所有内容使用boolean（可能必须覆盖）。

我需要创建一个访问器方法，它将返回被划掉的最后一个数字

1 个答案: