Question

我在编码和java方面都相当新，但我希望我能解决这个问题。我有一个while循环和内部，如果在扫描仪中输入了错误的值，我有一个while语句。但是，当我运行代码时，它总是运行while命令一次，无论它是不正确还是正确，然后正确运行代码。

import java.util.Scanner;
public class Practice {
public static void main (String [] args) {
int x = 0;
int i = 0;
int n = 0;
String S1 = "";

Scanner user = new Scanner(System.in);


do
{
    System.out.println("Enter an integer between 1 and 15: ");
    x = user.nextInt();



        while ( x < 1 || x > 15);
        {
            System.out.println("Incorrect integer. Must be between 1 and 15. Try again: ");
            x = user.nextInt();
        }

    n = 1;  


}
while (n != 1);


for (i = 1; i <= x; i++)
{
    S1 = S1 + "X";
}

for (n = 1; n <= x; n++)
{
    System.out.println(S1);
}


    }


}

提前非常感谢你。

Answer 1

从while循环中删除额外的;

像这样：

  while ( x < 1 || x > 15){
            System.out.println("Incorrect integer. Must be between 1 and 15. Try again: ");
            x = user.nextInt();
}

Answer 2

while（x <1 || x> 15）; Semi-Colon将终止逻辑，控制将始终传递到下一行。编码时要小心：D

Answer 3

删除额外的分号。
同时关闭扫描仪对象（用户）。

检查更新的代码。

public class Practice {
    public static void main(String[] args) {
        int x = 0;
        int i = 0;
        int n = 0;
        String S1 = "";

        Scanner user = new Scanner(System.in);
        do {
            System.out.println("Enter an integer between 1 and 15: ");
            x = user.nextInt();

            while (x < 1 || x > 15)
            {
                System.out.println("Incorrect integer. Must be between 1 and 15. Try again: ");
                x = user.nextInt();
            }

            n = 1;

        } while (n != 1);

        for (i = 1; i <= x; i++) {
            S1 = S1 + "X";
        }

        for (n = 1; n <= x; n++) {
            System.out.println(S1);
        }

        user.close();

    }

}

Java：即使条件为false，Loop仍然在运行

3 个答案: