代碼在 Java（數組）中不起作用

Question

我有一項作業要編寫一個代碼，要求您提供 10 個座位（有些已被占用，有些是空的），您需要獲得一個座位，檢查它是否可用，如果沒有找到最近的空座位。

有時我的代碼有效，但大多數時候無效。 有人能幫我嗎？

import java.util.Scanner;

public class Main {
    static Scanner reader = new Scanner(System. in );

    public static void main(String[] args) {
        int mult = 1;
        int[] manage = new int[10];
        System.out.println(" 0- empty   1-taken ");
        for (int i = 0; i < 10; i++) {
            System.out.println("enter the " + (i + 1) + " place");
            manage[i] = reader.nextInt();
        }
        int a = 0, check = 0;
        System.out.println("What the place you want to seat in?: ");
        a = (reader.nextInt()) + 1;
        System.out.println("checking...");
        while (check != 5) {
            if (manage[a] == 0) {
                System.out.println(" your seat is in the " + a + " place");
                check = 5;
            } else if (manage[a - mult] == 0) {
                System.out.println(" your seat is in the " + ((a - mult) + 1) + " place");
                check = 5;
            } else if (manage[a + mult] == 0) {
                System.out.println(" your seat is in the " + ((a + mult) + 1) + " place");
                check = 5;
            } else {
                mult++;
            }
        }
    }
}   

Answer 1

我想你想要的這條線是

a = (reader.nextInt()) - 1;

代替

a = (reader.nextInt()) + 1;

由於您始終為所有輸出顯示“實際索引 + 1”，即
用戶處理 1 - 10 而不是 0 - 9 ？

注意：如果值 < 0或值 >= 數組長度， manage[a - mult] 和 manage[a + mult] 可以拋出 ArrayIndexOutOfBoundsException 。

注意#2：在else子句中，一旦mult >= 數組長度，您就可以跳出循環。 如果您不添加它，如果所有座位從一開始就被占用，則循環將不斷重復。

因此，在訪問該數組索引之前添加檢查，如下所示：

if (manage[a] == 0) {
    System.out.println("Your seat is in the " + a + " place");
    check = 5;
} else if ( a - mult >= 0 && manage[a - mult] == 0) {
    System.out.println("Your seat is in the " + ((a - mult) + 1)
            + " place");
    check = 5;
} else if (a + mult < manage.length && manage[a + mult] == 0) {
    System.out.println("Your seat is in the " + ((a + mult) + 1)
            + " place");
    check = 5;
} else {
    mult++;
    // Check is necessary here, infinite loop if all seats are taken!
    if(mult >= manage.length) {
        System.out.println("All seats taken!");
        break;
    }
}

輸入/輸出（更改后）：

0 - Empty  1 - Taken 
Enter the 1 place: 0
Enter the 2 place: 0
Enter the 3 place: 1
Enter the 4 place: 1
Enter the 5 place: 1
Enter the 6 place: 1
Enter the 7 place: 1
Enter the 8 place: 1
Enter the 9 place: 1
Enter the 10 place: 1
What is the place you want to sit in?: 10
checking...
Your seat is in the 2 place

0 - Empty  1 - Taken 
Enter the 1 place: 1
Enter the 2 place: 1
Enter the 3 place: 1
Enter the 4 place: 1
Enter the 5 place: 0
Enter the 6 place: 1
Enter the 7 place: 1
Enter the 8 place: 1
Enter the 9 place: 0
Enter the 10 place: 1
What is the place you want to sit in?: 1
checking...
Your seat is in the 5 place

在上面的例子中，用戶輸入 10，但你的程序檢查數組索引 9。
數組索引 9 被占用，所以你檢查數組索引 8 (9-1)，它是空的，並告訴用戶座位 #9 是他的座位。