java - 如何获取 for 循环迭代内生成的值并在其外部以相同的方法使用它们？

Question

我希望能够从 for 循环中取出值，并为 for 循环的单独迭代生成单独的值，以便我可以将它们放入 for 循环下面的比较 if/else 语句中。

public static void calculateBirthdays(Scanner console) {
        //Print purpose
        System.out.println("This program compares two birthdays");
        System.out.println("and displays which one is sooner.");

        Calendar cal = Calendar.getInstance();
        int todayYear = cal.get(Calendar.YEAR);
        int todayMonth = cal.get(Calendar.MONTH)+1;
        int todayDay = cal.get(Calendar.DAY_OF_MONTH);

        SimpleDateFormat d = new SimpleDateFormat();

        int todayDayValue = absDayVal(todayMonth, todayDay, todayYear);

        System.out.println("Today is " + d.format(cal.getTime()) + ", day #" + todayDayValue + " of the year.");

        for (int i = 1; i <= 2; i++) {
            System.out.println("Person " + i + ":\nWhat month, day and year were you born?");

            int month = console.nextInt();
            int day = console.nextInt();
            int year = console.nextInt();

            int daysPassed = absDayVal(month, day, year);
            int daysInYear = leapYear(todayYear);

            int daysUntilBday = daysAway(daysPassed, todayDayValue, daysInYear);

            DecimalFormat df = new DecimalFormat("0.##");

            System.out.println(month + "/" + day + "/" + todayYear + " falls on day #" + todayDayValue + " of " + daysInYear + ".");

            if(todayDayValue == daysPassed){
                System.out.println("Happy birthday!");
            } else if (todayDayValue != daysPassed){
                System.out.println("Your next birthday is in " + daysUntilBday + " day(s).");
                System.out.println("That is " + df.format((percentUntil(daysUntilBday, daysInYear)) * 100) + " percent of a year away.");
            }
        }

        if(percent < percent) {
            System.out.println("Person 1's birthday is sooner.");
        } else if (percent < percent) {
            System.out.println("Person 2's birthday is sooner.");
        } else if (percent == percent) {
            System.out.println("Wow, you share the same birthday!");
        }


    }

Answer 1

您可以像这样在循环之外简单地声明它们。

int month;
int day;
int year;

for (int i = 1; i <= 2; i++) {
    System.out.println("Person " + i + ":\nWhat month, day and year were you born?");

    month = console.nextInt();
    day = console.nextInt();
    year = console.nextInt();
    ...
}

这个概念称为范围。 Here is an article这可能会让您更好地理解变量范围。