Java程序作业问题：输入字符串分割与星座计算错误排查

Hey there! Let's break down what's going wrong with your code and fix it up so it works exactly as you expect.

The Core Issue: Wrong mmdd Calculation #

The biggest mistake here is how you're computing the mmdd value. Right now you're using:

mmdd = a + b;

For input 01/06, this gives you 1 + 6 = 7—way off from the expected 106. Instead of adding the month and date, you need to concatenate them into a single numeric value. The correct formula is:

mmdd = a * 100 + b;

This shifts the month value two digits left (multiplying by 100) and appends the date, giving you the combined mmdd number you need.

Smaller Fixes & Improvements #

1. Avoid redundant split() calls: You're splitting the input string twice, which is unnecessary. Store the split result in an array first to make your code cleaner and more efficient.
2. Fix Capricorn's date range: Your current condition for Capricorn includes mmdd >= 11, but since mmdd is calculated as month*100 + date, the smallest possible January value is 101 (1/01). That condition should be mmdd >= 101 instead.
3. Close the scanner: It's good practice to close the Scanner object when you're done with it to free up resources.

Corrected Full Code #

import java.util.Scanner;

public class ZodiacSign {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int mmdd;
        int month;
        int day;
        
        System.out.print("Please enter your date of birth(MM/dd): ");
        String stringDate = scan.next();
        
        // Split once and reuse the result
        String[] dateParts = stringDate.split("/");
        month = Integer.parseInt(dateParts[0]);
        day = Integer.parseInt(dateParts[1]);
        
        // Calculate mmdd correctly
        mmdd = month * 100 + day;
        System.out.println("This is the mmdd value: " + mmdd);
        
        System.out.print("Result: ");
        if (mmdd >= 321 && mmdd <= 419) {
            System.out.println("ARIES");
        } else if (mmdd >= 420 && mmdd <= 520) {
            System.out.println("TAURUS");
        } else if (mmdd >= 521 && mmdd <= 620) {
            System.out.println("GEMINI");
        } else if (mmdd >= 621 && mmdd <= 722) {
            System.out.println("CANCER");
        } else if (mmdd >= 723 && mmdd <= 822) {
            System.out.println("LEO");
        } else if (mmdd >= 823 && mmdd <= 922) {
            System.out.println("VIRGO");
        } else if (mmdd >= 923 && mmdd <= 1022) {
            System.out.println("LIBRA");
        } else if (mmdd >= 1023 && mmdd <= 1121) {
            System.out.println("SCORPIO");
        } else if (mmdd >= 1122 && mmdd <= 1221) {
            System.out.println("SAGITTARIUS");
        } else if ((mmdd >= 1222 && mmdd <= 1231) || (mmdd >= 101 && mmdd <= 119)) {
            System.out.println("CAPRICORN");
        } else if (mmdd >= 120 && mmdd <= 218) {
            System.out.println("AQUARIUS");
        } else if (mmdd >= 219 && mmdd <= 320) {
            System.out.println("PISCES");
        }
        
        scan.close();
    }
}

Test It Out #

If you input 01/06 now, the code will calculate mmdd = 1 * 100 + 6 = 106, which falls right into the Capricorn range (101-119). You'll get the expected output: CAPRICORN.

内容的提问来源于stack exchange，提问作者daboogymenz06