java.time

Question

我试图获得自Java中Epoch以来的天数，周数，月数。

Java Calendar类提供了诸如calendar.get（GregorianCalendar.DAY_OF_YEAR）或Calendar.get（GregorianCalendar.WEEK_OF_YEAR）之类的东西，这是一个很好的开始，但它并不能完全满足我的需要。

在Java中有优雅的方法吗？

Answer 1

您可以使用Joda Time library非常轻松地执行此操作 - 除了使用标准的Java Date和Calendar类之外，我还可以使用它。使用库查看下面的示例：

MutableDateTime epoch = new MutableDateTime();
epoch.setDate(0); //Set to Epoch time
DateTime now = new DateTime();

Days days = Days.daysBetween(epoch, now);
Weeks weeks = Weeks.weeksBetween(epoch, now);
Months months = Months.monthsBetween(epoch, now);

System.out.println("Days Since Epoch: " + days.getDays());
System.out.println("Weeks Since Epoch: " + weeks.getWeeks());
System.out.println("Months Since Epoch: " + months.getMonths());

当我运行时，我得到以下输出：

Days Since Epoch: 15122
Weeks Since Epoch: 2160
Months Since Epoch: 496

Answer 2

java.time

使用Java 8及更高版本中内置的java.time类。

LocalDate now = LocalDate.now();
LocalDate epoch = LocalDate.ofEpochDay(0);

System.out.println("Days: " + ChronoUnit.DAYS.between(epoch, now));
System.out.println("Weeks: " + ChronoUnit.WEEKS.between(epoch, now));
System.out.println("Months: " + ChronoUnit.MONTHS.between(epoch, now));

<强>输出

Days: 16857
Weeks: 2408
Months: 553

Answer 3

Long currentMilli = System.currentTimeMillis();
Long seconds = currentMilli / 1000;
Long minutes = seconds / 60;
Long hours = minutes / 60;
Long days = hours / 24;
System.out.println("Days since epoch : "  + days);

或

System.out.println("Days since epoch : "  + ((int) currentMilli / 86400000));

Answer 4

令我惊讶的是，几乎所有答案实际上都在计算<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="XF_Login.Pages.RegisterPage" >至epoch之间的天数。使用now的过程非常简单：

java.time.LocalDate

Answer 5

Date.getTime() - 返回自此Date对象表示的1970年1月1日00:00:00 GMT以来的毫秒数。

您可以使用此功能，并了解您关心计算间隔中的毫秒数。

Answer 6

Calendar now = Calendar.getInstance();
Calendar cal = Calendar.getInstance();
cal.setTimeInMillis(0); // start at EPOCH

int days = 0
while (cal.getTimeInMillis() < now.getTimeInMillis()) {
  days += 1
  cal.add(Calendar.DAY_OF_MONTH, 1) // increment one day at a time
}
System.out.println("Days since EPOCH = " + days);

Answer 7

我不希望有一种优雅的方式，因为它不是一个非常常见的要求。我不禁想知道你为什么要这样做......

但无论如何，我这样做的方法是从Calendar中减去纪元日期，然后得到你想要的字段：

Calendar timeSinceEpoch = Calendar.getInstance();
timeSinceEpoch.add(Calendar.YEAR, -1970);

int yearsSinceEpoch = timeSinceEpoch.get(Calendar.YEAR);
int monthsSinceEpoch = timeSinceEpoch.get(Calendar.MONTH) + 12 * yearsSinceEpoch;

获取自Java中的Epoch以来的天数，周数和月数

7 个答案:

java.time