Java-While循环不会退出

Question

//无效的循环。 我一直按1,2、3、4或5，但不会退出循环。 该操作员似乎被分配了我输入的值，但仍不会退出while循环。 我试图用简单的数学运算编写一个基本的计算器，但这变成了一个非常烦人的问题。

import java.util.Scanner;
public class BasicCalculatorTwo {
    public static void main(String[] args){
        Scanner scanner = new Scanner(System.in);
        int operator;
        double fnum, snum, answer;
        operator = 0;

        System.out.println("Enter first number : ");
        fnum = scanner.nextDouble();
        System.out.println("Enter second number : ");
        snum = scanner.nextDouble();

        while(operator != 1 || operator != 2 || operator != 3 || operator != 4 || operator != 5 ){
            System.out.println();
            System.out.println(fnum + " ? " + snum + " = ");
            System.out.println("1 : Add");
            System.out.println("2 : Subtract");
            System.out.println("3 : Multiply");
            System.out.println("4 : Divide");
            System.out.println("5 : Modularize");
            operator = scanner.nextInt();
        }

        switch(operator){
            case 1:
                answer = fnum + snum;
                break;
            case 2:
                answer = fnum - snum;
                break;
            case 3:
                answer = fnum * snum;
                break;
            case 4:
                answer = fnum / snum;
                break;
            case 5:
                answer = fnum % snum;
                break;
            default:
                break;
            System.out.println(fnum + " ? " + snum + " = " + answer);
            scanner.close();
        }
    }
}

Answer 1

您循环条件是问题所在。

while (operator != 1 || operator != 2 || operator != 3 || operator != 4 || operator != 5)

它应该是

while (operator != 1 && operator != 2 && operator != 3 && operator != 4 && operator != 5)

基本上，您是说如果运算符为！= 1，则执行循环。 同样，其他每个人。 如果要使用&&运算符代替|| 它会好得多。

确实，您要说的是运算符> 1 && <5，然后循环，否则中断。

while(operator < 1 || operator > 5)
{
  DoPrintStuffHere();
}

从逻辑上考虑一下，您希望小于1或大于5的任何数字再次循环。