Question

如果用户输入特定输入，我必须退出循环。但我无法使用if循环来打破while循环。我也尝试在while循环中使用相同的条件，但这也不起作用。

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {    
        String quit;
        Scanner c = new Scanner(System.in);

        while (true) {
            leapOrNot y = new leapOrNot();  
            System.out.println("press x to stop or any other letter to continue");
            quit = c.next();
            if (quit == "x" || quit == "X") {
                break;
            }
       }
    }
}

class leapOrNot {
    final String isLeap = " is a leap year.";
    final String notLeap = " is not a leap year.";
    int year;
    public leapOrNot() {
        Scanner a = new Scanner(System.in);
        System.out.println("Enter a year after 1581: ");
        year = a.nextInt();
        /* if (a.hasNextInt() == false) {
            System.out.println("Enter a 4 digit integer: ");
            year = a.nextInt();
        }
        couldn't make this condition work either
        */
        while (year < 1582) {
            System.out.println("The year must be after 1581. Enter a year after 1581: ");
            year = a.nextInt();
            continue;
        }

        if (year % 4 == 0) {
            if(year % 400 == 0 && year % 100 == 0) {
                System.out.println(year + isLeap);
            }
            if (year % 100 == 0) {
                System.out.println(year + notLeap);
            }
            else { 
                System.out.println(year + isLeap);
            }
        }
        else {
            System.out.println(year + notLeap);
        }
    }
}

Answer 1

您应该使用String.equals()。替换为这两个中的任何一个

if (quit.charAt(0) == 'x' || quit.charAt(0) == 'X')
if (quit.equals("x") || quit.equals("X"))

以上任何一种都可以正常使用。

或只使用if(quit.equalsIgnoreCase("x"))

无法突破while循环。

1 个答案: