如何让Java星座程序中if-else分支触发后重新执行if判断逻辑？

Hey there! The problem here is that your program stops right after showing the invalid date message. To make it ask the user for input again until they provide a valid birth date, you just need to wrap your input and validation logic in a loop. Here's a straightforward fix using a do-while loop (perfect for this scenario since we want to run the input process at least once):

Modified Code #

import java.util.Scanner;

public class Horoscope {
    public Horoscope() {
        Scanner sc = new Scanner(System.in);
        String invalidMsg = "Please enter a valid date";
        int month;
        int day;
        boolean isInputValid; // Tracks if the entered date is valid

        do {
            isInputValid = true; // Assume valid initially; flip if invalid later
            System.out.println("What is your month of birth?");
            month = sc.nextInt();
            System.out.println("What is your day of birth?");
            day = sc.nextInt();

            // Existing zodiac logic
            if((month == 3 && day >= 20 && day <= 31) || (month == 4 && day >= 1 && day <= 19)) {
                System.out.println("You are an Aries");
            } else if((month == 4 && day >= 20 && day <= 30) || (month == 5 && day >= 1 && day <= 20)) {
                System.out.println("You are a Taurus");
            } else if((month == 5 && day >= 21 && day <= 31) || (month == 6 && day >= 1 && day <= 20)) {
                System.out.println("You are a Gemini");
            } else if((month == 6 && day >= 21 && day <= 30) || (month == 7 && day >= 1 && day <= 22)) {
                System.out.println("You are a Cancer");
            } else if((month == 7 && day >= 23 && day <= 31) || (month == 8 && day >= 1 && day <= 22)) {
                System.out.println("You are a Leo");
            } else if((month == 8 && day >= 23 && day <= 31) || (month == 9 && day >= 1 && day <= 22)) {
                System.out.println("You are a Virgo");
            } else if((month == 9 && day >= 23 && day <= 30) || (month == 10 && day >= 1 && day <= 22)) {
                System.out.println("You are a Libra");
            } else if((month == 10 && day >= 23 && day <= 30) || (month == 11 && day >= 1 && day <= 21)) {
                System.out.println("You are a Scorpio");
            } else if((month == 11 && day >= 22 && day <= 31) || (month == 12 && day >= 1 && day <= 21)) {
                System.out.println("You are a Sagittarius");
            } else if((month == 12 && day >= 22 && day <= 31) || (month == 1 && day >= 1 && day <= 19)) {
                System.out.println("You are a Capricorn");
            } else if((month == 1 && day >= 20 && day <= 31) || (month == 2 && day >= 1 && day <= 18)) {
                System.out.println("You are an Aquarius");
            } else if((month == 2 && day >= 19 && day <= 29) || (month == 3 && day >= 1 && day <= 20)) {
                System.out.println("You are a Pisces");
            } else {
                System.out.println(invalidMsg);
                isInputValid = false; // Mark input as invalid to trigger another loop iteration
            }
        } while (!isInputValid); // Repeat loop until valid input is received

        sc.close(); // Clean up the Scanner resource
    }

    public static void main(String[] args) {
        new Horoscope(); // Added main method to run the program
    }
}

Key Changes Explained #

• Loop Structure: The do-while loop ensures the input/validation process runs at least once, and repeats as long as the user enters an invalid date.
• Validation Flag: The isInputValid boolean tracks whether the entered date matches a valid zodiac range. We set it to false only in the else (invalid) branch, which tells the loop to run again.
• Resource Cleanup: Added sc.close() to properly close the Scanner, and a main method so you can actually run the program.

内容的提问来源于stack exchange，提问作者user12137309