2

这很有趣，我注意到了。在我能进一步解释它最好的地方之前，我会展示代码，你就会明白我的意思。

这是代码：

public class Qn3 {
    static BigDecimal[] accbal = new BigDecimal[19];
    private static Integer[] accnums = new Integer[19];

    public static void main(String[] args) {
        addaccount();

    }
    public static void addAccount() {

        int i = 0, accno, input, j, check;
        BigDecimal accbala;
        DecimalFormat df = new DecimalFormat("0.00");

        Scanner sc = new Scanner(System.in);
        Scanner in = new Scanner(System.in);
        accnums[1] = new Integer(1);

        while (accnums.length >= count(accnums)) {
            System.out.print("Enter the account number: ");
            while (sc.hasNext("[0-9]{7}")) {
                accno = sc.nextInt();
                System.out.print("Enter account balance: ");
                accbala = in.nextBigDecimal();

                for (j = 0; j < accnums.length; j++) {
                    if (accnums[j] == null)
                        break;
                    else if (accnums[j].equals(accno)) {
                        break;
                    }
                }

                if (j == accnums.length) {
                    System.out.print("No more than 20 accounts can be added.");
                } else if (accnums[j] != null) {
                    if ((accnums[j].equals(accno)))
                        System.out.println("Account already exists");
                    break;
                } else {
                    accnums[j] = accno;
                    accbala = accbala.setScale(2, RoundingMode.HALF_UP);
                    accbal[j] = accbala;
                    check = j;
                    System.out.println("Current number of accounts in the system: "
                                    + (check + 1)
                                    + "\nNumber of accounts still can be added: "
                                    + (20 - (check + 1)));

                }
            }

            while (!sc.hasNext("[0-9]{7}")) {
                System.out.println("Wrong NRIC");
                break;
            }
            while (accnums.length <= count(accnums)) {
                System.out.println("20 accounts have already been created");
                break;
            }
            break;
        }
    }

    private static int count(Integer[] array) {
        int count = 0;
        // accnums = new Integer[] {1,2};
        for (int index = 0; index < array.length; index++) {
            if (array[index] != null) {
                count++;
            }
        }
        // System.out.println("You have used " + count + " slots");
        return count;
    }
}

所以现在你已经看到了代码很难注意到的问题是这个，注意addaccount()方法中的行

 System.out.println("Current number of accounts in the system: "+(check+1)+"\nNumber of accounts still can be added: "+(20 - (check+1)));

这条线第一条check+1给我 1 然后下一条给我 3！然后下次我运行它给我 4 的方法，然后再给我 5 等等，2 发生了什么？

4

1 回答 1

2

您在 else 块中有那个 println，当 j == 1 时，您遇到了 else if 情况。尝试删除此行

accnums[1] = new Integer (1);
于 2012-08-27T04:58:50.110 回答