从使用类名作为输入的方法返回二维数组

Question

我在return gameBoard;行上收到错误消息“类型不匹配无法从 String[][] 转换为 GameBoard[][]” return gameBoard; . 如何更改我的公共类 GameBoard 以便我能够在 2D 数组中返回字符串值？ （我不想将方法返回类型更改为 String[][]）

public class GameBoard {

    String[][] gameBoard;


    /**
     * Constructor
     */

    public GameBoard() {
        gameBoard = new String[4][5];
    }   

    /**
     * Filling the playable board with Strings
     * @return
     */

     public GameBoard[][] fillGameBoard() {

        gameBoard[0][0] = new String("1");
        gameBoard[0][1] = new String("2");
        gameBoard[0][2] = new String("3");
        gameBoard[0][3] = new String("4");
        gameBoard[0][4] = new String("5");
        gameBoard[1][0] = new String("6");
        gameBoard[1][1] = new String("7");
        gameBoard[1][2] = new String("8");
        gameBoard[1][3] = new String("9");
        gameBoard[1][4] = new String("10");
        gameBoard[2][1] = new String("11");
        gameBoard[2][2] = new String("12");
        gameBoard[2][3] = new String("13");
        gameBoard[3][1] = new String("14");
        gameBoard[3][2] = new String("15");
        gameBoard[3][3] = new String("16");



        return gameBoard;

    }```

Answer 1

发生这种情况是因为您告诉编译器您将返回GameBoard[][]类型，但实际上返回的是String[][]类型，您可能会因为以与命名类相同的方式命名成员变量而混淆了自己。 您可能想为它取一个不那么令人困惑的名称。

通常，您为 GameBoard 定义类的方法很好，因为您可能希望稍后对其执行不同的操作，例如move()内容从 1 个单元格移动到另一个单元格或其他内容。 但请记住，您的“客户端类”不知道您的类内部的外观，因此您不能将GameObject存储为String[][] ，反之亦然

这是您的类的示例，其中包含有关如何声明使用 GameBoard 的变量以及建议的一些评论：（这将无法正常工作，您必须删除不想使用的方法，因为它们在返回类型）

public class GameBoard {

    String[][] gameBoard;

    /**
     * Constructor
     */
    public GameBoard() {
        gameBoard = new String[4][5];
    }   

    // Approach 1
     public void fillGameBoard() {

        gameBoard[0][0] = "1";
        gameBoard[0][1] = "2";
        gameBoard[0][2] = "3";
        gameBoard[0][3] = "4";
        gameBoard[0][4] = "5";
        gameBoard[1][0] = "6";
        gameBoard[1][1] = "7";
        gameBoard[1][2] = "8";
        gameBoard[1][3] = "9";
        gameBoard[1][4] = "10";
        gameBoard[2][1] = "11";
        gameBoard[2][2] = "12";
        gameBoard[2][3] = "13";
        gameBoard[3][1] = "14";
        gameBoard[3][2] = "15";
        gameBoard[3][3] = "16";
    }

    // Approach 2
    // If you really want to go with the way you had your declaration set up
    // GameBoard board = new GameBoard().fillGameBoard();
    // you would have to do this
    public GameBoard fillGameBoard() {
        fillGameBoard();

        return this;
    }

    // Approach 3
    // If you want to do this, you don't need your class at all and your fillGameBoard 
    // has to return a String[][] type. I would recommend against it though,
    // since you are using a highly object oriented language as Java
    public String[][] fillGameBoard() {
        fillGameBoard();

        return gameBoard;
    }

    public static void main(String[] args) {
        // Approach 1
        // I recommend this approach!
        GameBoard board2 = new GameBoard();
        board2.fillGameBoard();

        // Approach 2
        GameBoard board = new GameBoard().fillGameBoard();

        // Approach 3
        String[][] board3 = new GameBoard().fillGameBoard();
    }
}