java - if语句逻辑

Question

我的任务是为我正在学习的类(class)创建一个小型 Java 程序，但我在使用以下代码块时遇到了一些问题:

        System.out.println("Please enter your first name:");
    userName = sc.nextLine();
    System.out.println("What year were you born in?");
    birthYear = sc.nextInt();
    System.out.println("In the 'dd.mm' format, what are the day and month of your birth?");
    dayMonth = sc.nextDouble();
    //Cast the user input of type double to an int for the day of Birth
    dayOfBirth = dayMonth.intValue();

    //Cast the double value for month and cast it to an int
    dayMonth = dayMonth - dayOfBirth;
    dayMonth = dayMonth * 100;
    dayMonth = Math.rint(dayMonth);
    monthOfBirth = dayMonth.intValue();
if(birthYear == 2013 || birthYear == 2001 || birthYear == 1989 || birthYear == 1977 || birthYear == 1965 || birthYear == 1953 || birthYear == 1941)
{
    if(monthOfBirth == 9 || monthOfBirth == 10 || monthOfBirth == 11)
    {
        System.out.println(userName + " was born during Spring on " + monthOfBirthName + " " + dayOfBirth + " in Snake year " + birthYear);
    }
        else if(monthOfBirth != 9 || monthOfBirth != 10 || monthOfBirth != 11)
        {
            System.out.println(userName + " was born on " + monthOfBirthName + " " + dayOfBirth + " in Snake year " + birthYear);
        }
}
if(birthYear != 2013 || birthYear != 2001 || birthYear != 1989 || birthYear != 1977 || birthYear != 1965 || birthYear != 1953 || birthYear != 1941)
{
     if(monthOfBirth == 9 || monthOfBirth == 10 || monthOfBirth == 11)
    {
        System.out.println(userName + " was born during Spring on " + monthOfBirthName + " " + dayOfBirth + " " + birthYear);
    }   
        else if(monthOfBirth != 9 || monthOfBirth != 10 || monthOfBirth != 11)
        {
            System.out.println(userName + " was born on " + monthOfBirthName + " " + dayOfBirth + " " + birthYear);
        }
}

但是我的输出结果如下:

Please enter your first name:

Samuel

What year were you born in?

1977

In the 'dd.mm' format, what are the day and month of your birth?

09.09

Samuel was born during Spring on September 9 in Snake year 1977

Samuel was born during Spring on September 9 

我显然不希望重复输出，但是我无法看到我的 if 语句中的逻辑在哪里导致它重复。

如有任何帮助，我们将不胜感激。

谢谢大家

~山姆。

Answer 1

与其单独使用 2 个 if，不如将它们设为 if-else 或 if-else if。

if(birthYear == 2013 || birthYear == 2001 || birthYear == 1989 || birthYear == 1977 || birthYear == 1965 || birthYear == 1953 || birthYear == 1941){
    ....
}
else if(birthYear != 2013 || birthYear != 2001 ||...){
....
}

因为，如果你给出一个 if-if，那么两个 if 语句都会被执行，而如果你给出一个 if-else if，第二个 else if 只有在第一个 if 语句失败时才会执行。