Java 2D array object cannot be resolved to a variable?

Question

I have a class called game in which I use the default constructor to create and initialize a 2D array of objects from another class. However, in another method that I use to manipulate variables from the objects in the 2D array, I encounter an error that states "gameBoard (the object) cannot be resolved to a variable." The error is encountered only at the bottom of the second method.

public game() {
        // Start initialize game board
        grid[][] gameBoard = new grid[9][9];

        gameBoard[0][0] = new grid(" ", "N", true);
        gameBoard[0][1] = new grid("A", "N", true);
        gameBoard[0][2] = new grid("B", "N", true);
        gameBoard[0][3] = new grid("C", "N", true);
        gameBoard[0][4] = new grid("D", "N", true);
        gameBoard[0][5] = new grid("E", "N", true);
        gameBoard[0][6] = new grid("F", "N", true);
        gameBoard[0][7] = new grid("G", "N", true);
        gameBoard[0][8] = new grid("H", "N", true);
        gameBoard[1][0] = new grid("1", "N", true);
        gameBoard[2][0] = new grid("2", "N", true);
        gameBoard[3][0] = new grid("3", "N", true);
        gameBoard[4][0] = new grid("4", "N", true);
        gameBoard[5][0] = new grid("5", "N", true);
        gameBoard[6][0] = new grid("6", "N", true);
        gameBoard[7][0] = new grid("7", "N", true);
        gameBoard[8][0] = new grid("8", "N", true);

        for (int x = 1; x < 9; x++) {
            for (int y = 1; y < 9; y++) {
                gameBoard[x][y] = new grid();
            }
        }
        // End
    }

    public void placeUserShips() {
        // Start place user ships
        for (int x = 1; x <= 6; x++) {
            System.out.print("Enter the coordinates of your ship #" + x + ": ");
            String cell = input_scanner.nextLine();
            String letter = cell.substring(0, 1);
            switch (letter) {
                case "A":
                    letterCol = 1;
                    break;
                case "B":
                    letterCol = 2;
                    break;
                case "C":
                    letterCol = 3;
                    break;
                case "D":
                    letterCol = 4;
                    break;
                case "E":
                    letterCol = 5;
                    break;
                case "F":
                    letterCol = 6;
                    break;
                case "G":
                    letterCol = 7;
                    break;
                case "H":
                    letterCol = 8;
                    break;
                default:
                    letterCol = 0;
                    break;
            }
            number = Integer.parseInt(cell.substring(1, 2));
            if (gameBoard[letterCol][number].type == "" && number >= 1 && number <= 8) {
                gameBoard[letterCol][number].type = "s";
            } else {
                System.out.println("Sorry, those coordinates are already in use. Try again.");
                x -= 1;
            }
        }
        // End
    }

Answer 1

As in the question Java, “Variable name” cannot be resolved to a variable , this kind of errors happens when you refer to a undefined variable (or out of scope).

You can construct the gameBoard in game() and then return it to placeUserShips() :

public grid[][] game() {
    // Start initialize game board
    grid[][] gameBoard = new grid[9][9];

    // ...

    return gameBoard;
}

public void placeUserShips() {
    // Start place user ships
    grid[][] gameBoard = game();
    // ...
}

Or using a global variable (in the main you shall call game first):

private grid[][] gameBoard;
public void game() {
    // Start initialize game board
    gameBoard = new grid[9][9];

    // ...
}

public void placeUserShips() {
    // Start place user ships
    // ...
}