Question

我正在处理以下代码块：

    while (!userCorrect) {
        Scanner input = new Scanner(System.in);
        System.out.print("Guessing (round " + roundNumber1++ + "): Choosing your letter from a-z: ");
            String letter = input.nextLine();
            if (letter.length () > 1) {
                System.out.println("You should not enter more than 1 character");
                } 


        System.out.println("end of (round " + roundNumber2++ + ")");
    }
    }

我想要做的是在用户输入多个字符后，代码返回到：

System.out.print（“ Guessing（round” + roundNumber1 ++ +“）：从a-z中选择字母：”）;

直到仅选择1个字符，然后移至第2轮。

例如假设它是第一回合，并且用户输入了az。这将引发我的错误，说您不应输入超过1个字符，然后返回到：

猜测（第1轮）：从a-z中选择角色：

有什么想法吗？我可以使用它，但是它正在跳到下一轮，我希望它保持在同一轮直到有效输入为止。我一直在找几个小时，无法正常工作。

Answer 1

仅在收到有效输入后的处递增：

boolean userCorrect = false;
int roundNumber = 1;  // starting round

while (!userCorrect) {

    Scanner input = new Scanner(System.in);
    System.out.print("Guessing (round " + roundNumber + "): Choosing your letter from a-z: ");
    String letter = input.nextLine();

    if (letter.length () > 1) {
        System.out.println("You should not enter more than 1 character");
    }

    else{
        System.out.println("end of (round " + roundNumber + ")");
        roundNumber++;       // now increment
    }
}

请注意，此循环将继续进行，直到您将userCorrect = true设置在循环内的某个位置为止。

Answer 2

您可以像下面那样使用

while (!userCorrect) {
        Scanner input = new Scanner(System.in);
        System.out.print("Guessing (round " + roundNumber1 + "): Choosing your letter from a-z: ");
            String letter = input.nextLine();
            if (letter.length () > 1) {
                System.out.println("You should not enter more than 1 character");
                continue;
                } 

        System.out.println("end of (round " + roundNumber1 + ")");
        roundNumber1++;
    }

Answer 3

这是另一种方法，使用continue关键字基本上可以将执行强制回到循环的顶部。使用此实现，只需在需要时将done设置为true。

    public static void main(String[] args)
        {
            Scanner input = new Scanner(System.in);
            int roundNumber = 1;
            boolean done = false;

            do
            {
                System.out.println("Guessing (round " + roundNumber + "): Choosing your letter from a-z: ");
                String letter = input.nextLine();
                if(letter.length() > 1)
                {
                    System.out.println("You should not enter more than 1 character");
                    continue;
                }
                else
                {
                    roundNumber++;
                }

                //Set done to true based on some condition

            }while(!done);

        }
        //end main

获取无效输入后重新启动的代码（Java）

3 个答案: