如何为闰年增加一年中的打印天数

Question

我在添加它时遇到了问题，这样我的程序就会打印出某一年中的天数。让我困惑的是闰年。不想报废。

我很困惑，正试图自己把它拼凑起来，应该寻求帮助。我想知道是否有办法修复它，或者我是否必须放弃它，重新开始。到目前为止，我的问题是指定日期。因为我不确定我是否应该把日子按月分开，只需要每年的总数，闰年也要这样做。

if (month == 1) {
month1 = "January"; 
daysInMonth = 31;
} else if (month == 2 ) {
month1 = "February";
daysInMonth = 28;
} else if (month == 3) {
month1 = "March";
daysInMonth = 31;
} else if (month == 4) {
month1 = "April";
daysInMonth = 30;
} else if (month == 5) {
month1 = "May";
daysInMonth = 31;
} else if (month == 6) {
month1 = "June";
daysInMonth = 30;
} else if (month == 7) {
month1 = "July";
daysInMonth = 31;
} else if (month == 8) {
month1 = "August";
daysInMonth = 30;
} else if (month == 9 ) {
month1 = "September";
daysInMonth = 30;
} else if (month == 10) {
month1 = "October";
daysInMonth = 31;
} else if (month == 11) {
month1 = "November";
daysInMonth = 30;
} else if (month == 12) {
month1 = "December";
daysInMonth = 31;
} else if (month >= 13 ) {
System.out.println("this date does not exist please try again");
}
if (month <= 12) {
System.out.println("this is the year you put in " + year);
System.out.println("this is the month you entered " + month1);
System.out.println("this is how many days are in that year " + daysInMonth);
}
}

Answer 1

如果使用java.time，您将获得以下几个优势：

• 检查无效输入会更容易
• 你可以很容易地知道一年是否是闰年
• 您可以根据地区设置轻松打印月份名称甚至缩写，这意味着您可以切换语言和标准

下面是一个方法的小例子：

public static void printInformationAbout(int month, int year) {
// create an instance of month and year from the arguments
Year y = Year.of(year);
Month m = Month.of(month);

// collect information about the year
boolean isLeap = y.isLeap();
int days = y.length();
// and print that information
if (isLeap) {
System.out.println(year + " is a leap year and has " + days + " days");
} else {
System.out.println(year + " is a regular year and has " + days + " days");
}

// print month info (directly this time)
System.out.println(String.format("%s (month no. %d) has %d days in %d",
m.getDisplayName(TextStyle.FULL, Locale.ENGLISH),
m.getValue(),   //  number of the month
m.length(isLeap), // length of month in days
year));
}

如果你在main中使用了这个，我们可以这样说：

public static void main(String[] args) {
printInformationAbout(5, 2020);
}

你会得到以下输出：

2020 is a leap year and has 366 days
May (month no. 5) has 31 days in 2020