这是我所拥有的：

Scanner input = new Scanner(System.in);
    System.out.print("Enter a year: ");
    int Year = input.nextInt();
    System.out.print("Enter a month (first three letters with the first"
            + " letter uppercase): ");
    String Month = input.next();

    String ThirtyOne = "Jan" + "Mar" + "May" + "Jul" + "Aug" + "Oct" + "Dec";
    String DaysThirtyOne = ThirtyOne.substring(21) + "31";

    String Thirty = "Apr" + "Jun" + "Sep" + "Nov";
    String DaysThirty = Thirty.substring(12) + "30";

    String TwentyEight = "Feb";
    String DaysTwentyEight = TwentyEight.substring(3) + "28";
    String DaysLeapYear = TwentyEight.substring(3) + "29";


    boolean isLeapYear = ((Year % 4 == 0) && (Year % 100 != 0) && (Year % 400 == 0));

    if (ThirtyOne.contains(Month)) {
        System.out.println(Month + " " + Year + " has " + DaysThirtyOne 
                + " days in it.");
    }
    if (Thirty.contains(Month)) {
        System.out.println(Month + " " + Year + " has " + DaysThirty 
                + " days in it.");
    }
    if(TwentyEight.contains(Month)) {
        System.out.println(Month + " " + Year + " has " + DaysTwentyEight 
                + " days in it.");
    }
    if (isLeapYear) {
        System.out.println(Month + " " + Year + " has " + DaysLeapYear 
                + " days in it.");
    }

我是编程新手，所以如果这段代码看起来不成熟，我不会感到惊讶。无论如何，我让用户输入了一年零一个月（前三个字母）。我为a年创建了一个布尔变量，该变量表示用户输入的任何年份都需要被4、100和400整除。然后，我创建了一个if语句来确定是否是is年，以打印出“
Feb（任何年份用户输入）中有DaysLeapYear。”
我认为我的算法有问题，因为如果我要取出TwentyEight的if语句并仅保留the年if语句，则计算机甚至都不会打印出如果是was年，则Feb将有多少天。再说一次，我认为我在算法上出错了，