Java 如何从当前时间戳中减去一个小时
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How to subtract an hour from current timestamp
提问by kreya
How to subtract an hour from current time-stamp?
如何从当前时间戳中减去一个小时？
Calendar c = Calendar.getInstance();
System.out.println("current: "+c.getTime());
回答by Rohit Jain
Add -1to the Calendar.HOURattribute:
添加-1到Calendar.HOUR属性：
Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.HOUR, -1);
Oh! And with Joda Time, there you go:
哦！有了Joda Time，你就可以：
DateTime date = DateTime.now();
DateTime dateOneHourBack = date.minusHours(1);
Although difference might not be visible here, but it's a much more simple and better API than Dateand Calendarin JDK.
虽然这里可能看不到差异，但它是一个比JDKDate和Calendar在 JDK 中更简单和更好的 API 。
回答by BBdev
Add -1
添加 -1
add(int field,int amount)Adds or subtracts the specified amount of time to the given calendar field, based on the calendar's rules. For example, to subtract 1 hours from the current time of the calendar, you can achieve it by calling:
add(int field,int amount)根据日历的规则，向给定的日历字段添加或减去指定的时间量。例如，要从日历的当前时间减去 1 小时，可以通过调用来实现：
Calendar cal = Calendar.getInstance();
cal.add(Calendar.HOUR, -1);
回答by Rupesh
The answer you are looking for is
您正在寻找的答案是
cal.add(Calendar.HOUR, -numberOfHours);
cal.add(Calendar.HOUR, -numberOfHours);
where numberOfHoursis the amount you want to subtract.
numberOfHours您要减去的金额在哪里。
You can also refer this link for more information
您也可以参考此链接以获取更多信息
回答by Kedar1442
call add() method with a negative parameter if you want to subtract and positive parameter if you want to add the hour.
如果要减去，请使用负参数调用 add() 方法，如果要添加小时，请调用正参数。
for adding 2 hours,
增加2小时，
calendar.add(Calendar.Hour,2);
for subtracting 3 hours,
减去3小时，
calendar.add(Calendar.Hour,-3);
回答by pnathan
Calendar cal = Calendar.getInstance();
cal.add(Calendar.HOUR_OF_DAY, -1);
