java - 为什么我的方法在运行时会重复

Question

public class PalindromicPrimes {

    public static void main (String[] args) {
        userInt();
        System.out.println("The palindromic primes less than " + userInt() +
                           " are:");
        for (int i = 0; i <= userInt(); i++) {
            if (isPrime() && isPalindrome()) {
                System.out.println(i);
            }
        }

    }

    private static boolean isPrime() {
         if (userInt() == 2 || userInt() == 3) {
            return true;
        }
        if (userInt() % 2 == 0) {
            return false;
        }
        int sqrt = (int) Math.sqrt(userInt()) + 1;
        for (int i = 3; i < sqrt; i += 2) {
            if (userInt() % i == 0) {
                return false;
            }
        }
        return true;
    }

    private static boolean isPalindrome() {
        if (userInt() < 0)
        return false;
    int div = 1;
    while (userInt() / div >= 10) {
        div *= 10;
    }
    while (userInt() != 0) {
        int x = userInt();
        int l = x / div;
        int r = x % 10;
        if (l != r)
            return false;
        x = (x % div) / 10;
        div /= 100;
    }
    return true;
    }
    private static int userInt() {
        Scanner s = new Scanner(System.in);
        System.out.print("Enter a positive integer: ");
        int userInt = s.nextInt();
        return userInt;
    }
}

是否有不同的方式来获取用户输入？或者我可以保持这样吗？当它运行时，它只是不断提示用户输入。

Answer 1

像这样重新排列:

public static void main (String[] args) {

    //get it and save it here!
    int userValue = userInt();
    System.out.println("The palindromic primes less than " + userValue +
                   " are:");
    for (int i = 0; i <= userValue; i++) {
        if (isPrime(userValue) && isPalindrome(userValue)) {
            System.out.println(i);
        }
    }

}

然后还更新所有关心此“userInt”值的方法。

每次调用 userInt() 时，您都在告诉代码从命令行获取新值。