Java日历的设置值不会提供预期的日期时间
发布时间:2020-12-14 05:03:26 所属栏目:Java 来源:网络整理
导读:我有一个小时,分钟,日期和毫秒时间戳,并且正在尝试创建一个表示时间的Date对象.时间戳在Eastern Daylight Time中提供. 在解剖这个问题时,我创建了一些简单的测试代码来看看发生了什么,并且已经观察到以下内容: Date today = new Date(); int hour = 4,min =
我有一个小时,分钟,日期和毫秒时间戳,并且正在尝试创建一个表示时间的Date对象.时间戳在Eastern Daylight Time中提供.
在解剖这个问题时,我创建了一些简单的测试代码来看看发生了什么,并且已经观察到以下内容: Date today = new Date(); int hour = 4,min = 0,sec = 0,ms = 64; boolean print = true; Calendar cal = GregorianCalendar.getInstance(); if(print) System.out.println("After initializing,time is: "+cal.getTime()); cal.clear(); if(print) System.out.println("After clearing,time is: "+cal.getTime()); cal.setTime(today); if(print) System.out.println("After setting date,time is: "+cal.getTime()); cal.set(Calendar.HOUR_OF_DAY,hour); if(print) System.out.println("After setting hour,time is: "+cal.getTime()); cal.set(Calendar.MINUTE,min); if(print) System.out.println("After setting minute,time is: "+cal.getTime()); cal.set(Calendar.SECOND,sec); if(print) System.out.println("After setting second,time is: "+cal.getTime()); cal.set(Calendar.MILLISECOND,ms); if(print) System.out.println("After setting milliseconds,time is: "+cal.getTime()); cal.setTimeZone(TimeZone.getTimeZone("EDT")); System.out.println("After setting time zone,time is: "+cal.getTime()); 这产生的输出: After initializing,time is: Tue Jan 07 16:01:59 EST 2014 After clearing,time is: Thu Jan 01 00:00:00 EST 1970 After setting date,time is: Tue Jan 07 16:01:59 EST 2014 After setting hour,time is: Tue Jan 07 04:01:59 EST 2014 After setting minute,time is: Tue Jan 07 04:00:59 EST 2014 After setting second,time is: Tue Jan 07 04:00:00 EST 2014 After setting milliseconds,time is: Tue Jan 07 04:00:00 EST 2014 After setting time zone,time is: Tue Jan 07 04:00:00 EST 2014 但是,如果我稍微更改代码: boolean print = false; 我得到以下(不同)结果(!) After setting time zone,time is: Mon Jan 06 23:00:00 EST 2014 有人知道为什么会发生这种情况吗? 解决方法
您需要先设置时区.请参阅下面的GregorianCalendar.setTimeZone的定义:
public void setTimeZone(TimeZone value) { zone = value; sharedZone = false; /* Recompute the fields from the time using the new zone. This also * works if isTimeSet is false (after a call to set()). In that case * the time will be computed from the fields using the new zone,then * the fields will get recomputed from that. Consider the sequence of * calls: cal.setTimeZone(EST); cal.set(HOUR,1); cal.setTimeZone(PST). * Is cal set to 1 o'clock EST or 1 o'clock PST? Answer: PST. More * generally,a call to setTimeZone() affects calls to set() BEFORE AND * AFTER it up to the next call to complete(). */ areAllFieldsSet = areFieldsSet = false; } (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |