Calendar.getTime（）中的怪异IllegalArgumentException [英] Weird IllegalArgumentException in Calendar.getTime()

问题描述

此完全简单的测试因 IllegalArgumentException（ H​​OUR_OF_DAY 2-> 3）而失败，我看不出原因。您可以将小时，天，月，年中的任何一个更改为任何其他值，然后测试成功。未能通过我测试的任何JRE。似乎是GregorgianCalendar实现中的内部问题？还是我遗漏了一些明显的东西？

This perfectly simple test fails with IllegalArgumentException("HOUR_OF_DAY 2 -> 3"), and I see no reason why. You can change any of the hours, days, months, years to any other value and the test succeeds. Fails in any of the JRE's I tested on. Seems to be an internal problem in the GregorgianCalendar implementation? Or am I missing something obvious?

import java.util.Calendar;

public class DateTest extends TestCase
{
    /** test if 2011/03/27 02:30:00 converts to a valid date.
     * shouldn't throw any exception, however this throws 
     * IllegalArgumentException("HOUR_OF_DAY 2 -> 3)
     */
    @Test
    public void testDate()
    {
        Calendar cal = Calendar.getInstance();
        cal.setLenient(false);
        cal.clear();
        cal.set(Calendar.SECOND, 00);
        cal.set(Calendar.MINUTE, 30);
        cal.set(Calendar.HOUR_OF_DAY, 02);
        cal.set(Calendar.DAY_OF_MONTH, 27);
        cal.set(Calendar.MONTH, 03 - 1); // needs to be 0-based
        cal.set(Calendar.YEAR, 2011);
        cal.getTime();
    }
}

推荐答案

此日期和时间组合在您的时区中不存在，因为它会由于夏令时而陷入中断。

This date and time combination doesn't exist in your timezone, because it falls into discontinuity caused by daylight savings.

由于您配置了 setLenient（false） ，日历在您尝试输入不存在的日期时正确地引发了异常

Since you configured setLenient(false), Calendar correctly throws an exception when you try to enter a non-existing date.

经验法则：如果您在日期和时间计算中看到一些奇怪的东西，则怀疑是夏时制。

A rule of thumb: if you see something weird in date and time calculations, suspect daylight savings.

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