Naval Observatory, particularlyĪnd their definitions of 'Systems of Time' at: An interesting source ofįurther information is the U.S. Global positioning system (GPS) is synchronized to UTC but is Well for example, the time scale used by the satellite-based Seconds are introduced as needed into UTC so as to keep UTC withinĠ.9 seconds of UT1, which is a version of UT with certainĬorrections applied.

In complicated ways), UT does not always flow uniformly. Because theĮarth's rotation is not uniform (it slows down and speeds up Practical purposes is an invisibly fine hair to split. Theĭistinction between UTC and UT is that UTC is based on an atomicĬlock and UT is based on astronomical observations, which for all

The 'civil' name for the standard UT is the Time (GMT), which is equivalent to universal time (UT). Some computer standards are defined in terms of Greenwich mean Most computer clocks are not accurate enough to be able to reflect

Year 1995 was 61 seconds long, thanks to an added leap second. Second is always added as the last second of the day, and always Is an extra second, called a 'leap second.' The leap In UTC, however, about once every year or two there Nearly all modern operating systems assume that 1 day = The corresponding methods in Date are deprecated.Īlthough the Date class is intended to reflectĬoordinated universal time (UTC), it may not do so exactly,ĭepending on the host environment of the Java Virtual Machine. As of JDK 1.1, theĬalendar class should be used to convert between dates and timeįields and the DateFormat class should be used to format and Unfortunately, the API for these functions was notĪmenable to internationalization. It also allowed the formatting and parsing It allowed the interpretation of dates as year, month, day, hour, Prior to JDK 1.1, the class Date had two additionalįunctions. The class Date represents a specific instant

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