java - 我有一个 if 语句问题

Question

我已经编写了程序并运行了它，但是我不知道如何在我使用无效数字运行程序时防止两个 println 语句都出现。它基本上是一个程序，您可以在其中输入月份和日期(以数值表示)，输出将是季节。这是代码:

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

    int month;
    int day;
    String season = "seasons";

    System.out.println("Enter a month: ");
    month = in.nextInt();

    System.out.println("Enter a day: ");
    day = in.nextInt();

    String winter = "winter";
    String spring = "spring";
    String summer = "summer";
    String fall = "fall";

    System.out.println("Month="+ month +" Day= "+day);


    if (month <= 3)
    {
        season = winter;
    }
    else if (month <= 6)
    {
        season = spring;
    }
    else if (month <= 9)
    {
        season = summer;
    }
    else if (month <= 12)
    {
        season = fall;
    } else {
        System.out.println("The value is invalid.");
    }

    System.out.println(season);
    }
}

Answer 1

写:

String season = null;

然后在最后一个if之前检查:

if(season == null){
    //print invalid
} else {
    //print corresponding season
}