SimpleDateFormat的机器人没有格式化预期 [英] SimpleDateFormat android not formatting as expected

问题描述

我想使用的SimpleDateFormat格式化由3个整数psented日期重新$ P $。
它看起来是这样的：

I'm trying to use SimpleDateFormat for formatting a date represented by 3 ints. It looks like this:

...
SimpleDateFormat sdfHour = new SimpleDateFormat("HH");
SimpleDateFormat sdfMinute = new SimpleDateFormat("mm");
SimpleDateFormat sdfSecond = new SimpleDateFormat("ss");

Calendar c = Calendar.getInstance();
c.setTimeZone(TimeZone.getDefault());
int hours = c.get(Calendar.HOUR_OF_DAY);
int minutes = c.get(Calendar.MINUTE);
int seconds = c.get(Calendar.SECOND);

String string_hours = sdfHour.format(hours);
String string_minutes = sdfMinute.format(minutes);
String string_seconds = sdfSecond.format(seconds);

和的输出

Log.d("tag", "Time string is: " + string_hours + ":" + string_minutes + ":" + string_seconds);

总是

Time string is: 19:00:00

我在做什么错在这里？

What am I doing wrong here?

推荐答案

SimpleDateFormat.format需要一个日期，而不是​​一个int。您使用的方法，这是重载版本接受一个长期的，实际上是从的时代，不到一小时一分钟或第二期待毫秒为你做的。

SimpleDateFormat.format expects a Date, not an int. The method you're using, which is the overloaded version that accepts a long, is actually expecting milliseconds from the epoch, not an hour a minute or a second as you're doing.

使用它应该是正确的做法：

The right way of using it should be :

SimpleDateFormat sdfHour = new SimpleDateFormat("HH:mm:ss");
String timeString = sdfHour.format(new Date());

使用新的Date（）在这个例子中，将给你当前时间。如果您需要格式化某个时间（比如一小时前，或从数据库等东西..）传递到格式正确的日期实例。

Using "new Date()" as in this example, will give you the current time. If you need to format some other time (like one hour ago, or something from a database etc..) pass to "format" the right Date instance.

如果您需要的分离，因为某些原因，那么你仍然可以使用，但是，这个另一种方式：

If you need the separated, for some reason, then you can still use it, but this other way :

SimpleDateFormat sdfHour = new SimpleDateFormat("HH");
SimpleDateFormat sdfMinute = new SimpleDateFormat("mm");
SimpleDateFormat sdfSecond = new SimpleDateFormat("ss");

Date now = new Date();

String string_hours = sdfHour.format(now);
String string_minutes = sdfMinute.format(now);
String string_seconds = sdfSecond.format(now);

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