java - 为什么我会收到越界错误？

Question

这个问题已经有答案了:

What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it? (25 个回答)

已关闭 6 年前。

public static void randomNumberGame() {
    Scanner input = new Scanner(System.in);
    Random r = new Random();
    int x; 
    int y; 
    int random;
    int total = 0;
    int[][] board = new int[5][5];

    for (int i = 0; i < 5; i++) {
        System.out.print(" " + (i + 1) + " ");
    }
    System.out.println("");

    for (int i = 0; i < board.length; i++) {
        System.out.print(i + 1);
        for (int j = 0; j < board[0].length; j++) {
            board[i][j] = 0;
            System.out.print("[ ]");
        }
        System.out.println("");
    }

    for (int i = 0; i < board.length; i++) {
        for (int j = 0; j < board[0].length; j++) {
            random = r.nextInt(10) + 1;
            if (board[i][j] == 0) {
                board[i][j] = random;
            }

        }
    }

    for (int i = 0; i < 3; i++) {
        System.out.println("Please choose x coordinate for spot " + (i + 1));
        x = input.nextInt();
        System.out.println("Please choose y coordinate for spot " + (i + 1));
        y = input.nextInt(); 

        total += board[x][y];
            System.out.println(total);            

    }


}

输出如下:

1 2 3 4 5

1[ ][ ][ ][ ][ ]

2[ ][ ][ ][ ][ ]

3[ ][ ][ ][ ][ ]

4[ ][ ][ ][ ][ ]

5[ ][ ][ ][ ][ ]

Please choose x coordinate for spot 1: 5

Please choose y coordinate for spot 1: 5

异常堆栈跟踪 -

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 5
at chapter.pkg9.and.pkg10.test.Chapter9And10Test.randomNumberGame(Chapter9And10Test.java:117)
at chapter.pkg9.and.pkg10.test.Chapter9And10Test.main(Chapter9And10Test.java:22) C:\Users\Lance\AppData\Local\NetBeans\Cache\8.2\executor-snippets\run.xml:53: Java returned: 1
BUILD FAILED (total time: 1 second)

第 117 行包含此 total += board[x][y];

Answer 1

因为 5(您为 x 和 y 输入的值)不是有效的 x 或 y 值。数组的有效索引为 0 到 4(含)。 (就像在所有循环设置中一样。)要么让用户输入 0-4(含)之间的值，要么允许他们输入 1-5(含)并从 x 中删除 1和 y 在使用它们之前。