[英]java GregorianCalendar adding hour strange behavior
I have a problem with GregorianCalendar so if you please can help me out with it. 我的GregorianCalendar有问题,所以请您帮我解决。 First I'll give you my code:
首先,我给你我的代码:
private String changeClock(String day, String clock, int change) {
String time="";
DateFormat df=new SimpleDateFormat("yyyy-MM-dd hh:mm");
try {
Date d=df.parse(day+" "+clock);
GregorianCalendar g=new GregorianCalendar();
g.setTime(d);
g.add(GregorianCalendar.HOUR_OF_DAY, change);
time=g.get(GregorianCalendar.YEAR)+"-"
+(g.get(GregorianCalendar.MONTH)+1)+"-"
+g.get(GregorianCalendar.DAY_OF_MONTH)+" "
+g.get(GregorianCalendar.HOUR_OF_DAY)+":"
+g.get(GregorianCalendar.MINUTE);
} catch (Exception e) {
e.printStackTrace();
}
return time;
}
Let me explain what is happening. 让我解释一下发生了什么。 I have a GUI with + and - button.
我有一个带有+和-按钮的GUI。 When someone press + it add one hour, or if - is pressed then take one hour.
当有人按下+时,会增加一小时;如果按下-,则需要一小时。
Now example, time is 23:00 and I press +, it is everything ok and it jumps to 00:00 of the next day. 现在举个例子,时间是23:00,我按+,就可以了,它跳到了第二天的00:00。 Problems are on 12:00.
问题在12:00。 If it is 12:00 and I press + it goes to 1:00 and that goes on and on.
如果是12:00,然后按+,则转到1:00,然后继续。 It doesn't move to the next day even after 2x12 hours or 21465x12 hours.
即使经过2x12小时或21465x12小时,它也不会移动到第二天。 Moving backward is a little better if I can say so.
如果可以这样说,向后移动会更好一些。 When it is 00:00 and I press - it changes to yesterday 23:00 (also date changes).
当它是00:00时,我按-它更改为昨天23:00(日期也更改)。 If I then press + it changes also one day forward (so to today in this case).
如果我再按+,则它也会在一天前更改(在这种情况下,更改为今天)。
What have I done wrong or what more should I write to my code? 我做错了什么,或者应该写些什么?
Thanks for your help guys. 感谢您的帮助。
Your date format is wrong... 您的日期格式有误...
You're using hh
, which is a representation of the "Hour in am/pm (1-12)" , so a time of 1pm is been converted to 1am instead. 您使用的是
hh
,它表示“小时在am / pm(1-12)中” ,因此将1pm的时间转换为1am。
You should be using HH
which is aa representation of the "Hour in day (0-23)" . 您应该使用
HH
,它表示“一天中的小时(0-23)” 。
Either that, or you need supply a date/time format with the am/pm marker... 要么,要么您需要提供带有am / pm标记的日期/时间格式...
Using either DateFormat df=new SimpleDateFormat("yyyy-MM-dd HH:mm");
使用
DateFormat df=new SimpleDateFormat("yyyy-MM-dd HH:mm");
or DateFormat df=new SimpleDateFormat("yyyy-MM-dd hh:mm a");
或
DateFormat df=new SimpleDateFormat("yyyy-MM-dd hh:mm a");
Instead of relying on String
date/time values, you should be passing in and back a Date
object, leave the formatting for the display. 而不是依赖于
String
日期/时间值,您应该传入和传回Date
对象,并保留显示格式。
LocalDateTime.parse(
"2016-01-02 12:34:56".replace( " " , "T" )
)
The Answer by MadProgrammer is correct: Wrong code used in formatting pattern. MadProgrammer的答案是正确的:格式化模式中使用的代码错误。 But there is an even easier and better approach.
但是,有一种更轻松,更好的方法。
You are using troublesome old date-time classes now supplanted by the java.time classes. 您正在使用麻烦的旧日期时间类,而现在却被java.time类所取代。
Your input format in almost in standard ISO 8601 format. 您的输入格式几乎采用标准的ISO 8601格式。 Just replace the SPACE in middle with a
T
. 只需将中间的SPACE替换为
T
。
String input = "2016-01-02 12:34:56".replace( " " , "T" );
The java.time classe use ISO 8601 formats by default. 默认情况下,java.time类使用ISO 8601格式。 So need to specify a formatting pattern at all, so no formatting codes to get wrong.
因此,根本不需要指定格式格式,因此没有格式代码会出错。
LocalDateTime ldt = LocalDateTime.parse( input );
We parse as a LocalDateTime
because the input lacks information about offset-from-UTC or time zone. 我们将其解析为
LocalDateTime
因为输入缺少有关UTC偏移量或时区的信息。 If this value was meant for UTC, apply an offset to get an OffsetDateTime
. 如果此值用于UTC,则应用偏移量以获得
OffsetDateTime
。
OffsetDateTime odt = ldt.atOffset( ZoneOffset.UTC );
If meant for some time zone, transform into a ZonedDateTime
. 如果要用于某个时区,请转换为
ZonedDateTime
。
ZoneId z = ZoneId.of( "America/Montreal" );
ZonedDateTime zdt = ldt.atZone( z );
The java.time framework is built into Java 8 and later. java.time框架内置于Java 8及更高版本中。 These classes supplant the troublesome old date-time classes such as
java.util.Date
, .Calendar
, & java.text.SimpleDateFormat
. 这些类取代了麻烦的旧日期时间类,例如
java.util.Date
, .Calendar
和java.text.SimpleDateFormat
。
The Joda-Time project, now in maintenance mode , advises migration to java.time. 现在处于维护模式的Joda-Time项目建议迁移到java.time。
To learn more, see the Oracle Tutorial . 要了解更多信息,请参见Oracle教程 。 And search Stack Overflow for many examples and explanations.
并在Stack Overflow中搜索许多示例和说明。
Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport and further adapted to Android in ThreeTenABP (see How to use… ). 大部分的java.time功能后移植到Java 6和7 ThreeTen,反向移植 ,并进一步适应的Android在ThreeTenABP (见如何使用...... )。
The ThreeTen-Extra project extends java.time with additional classes. ThreeTen-Extra项目使用其他类扩展了java.time。 This project is a proving ground for possible future additions to java.time.
该项目为将来可能在java.time中添加内容提供了一个试验场。 You may find some useful classes here such as
Interval
, YearWeek
, YearQuarter
, and more. 您可能会在这里找到一些有用的类,例如
Interval
, YearWeek
, YearQuarter
等。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.