Date and Calendar are really the same fundamental concept (both represent an instant in time and are wrappers around an underlying long value). One could argue that Calendar is actually even more broken than Date is, as it seems to offer concrete facts about things like day of the week and time of day, whereas if you change its timeZone property, the concrete turns into blancmange! Neither objects are really useful as a store of year-month-day or time-of-day for this reason. Use Calendar only as a calculator which, when given Date and TimeZone objects, will do calculations for you. Avoid its use for property typing in an application. Use SimpleDateFormat together with TimeZone and Date to generate display Strings. If you're feeling adventurous use Joda-Time, although it is unnecessarily complicated IMHO and is soon to be superceded by the JSR-310 date API in any event. I have answered before that it is not difficult to roll your own YearMonthDay class, which uses Calendar under the hood for date calculations. I was downvoted for the suggestion but I still believe it is a valid one because Joda-Time (and JSR-310) are really so over-complicated for most use-cases.

Java 8，新的Java。应该使用时间包。

对象是不可变的，时区和日光节约被考虑在内。

你可以从一个旧的java.util.Date对象中创建一个ZonedDateTime对象，就像这样:

    Date date = new Date();
    ZonedDateTime zonedDateTime = date.toInstant().atZone(ZoneId.systemDefault());

有点晚了，但是Java在JDK 8中有一个新的日期时间API。您可能希望升级JDK版本并采用该标准。没有更多凌乱的日期/日历，没有更多第三方罐子。

Date是一个更简单的类，主要是为了向后兼容。如果需要设置特定的日期或进行日期计算，请使用Calendar。日历也处理本地化。date之前的日期操作函数已弃用。

就我个人而言，如果有选择的话，我倾向于使用以毫秒为单位的时间作为long(或long，视情况而定)或Calendar。

Date和Calendar都是可变的，这在API中使用时往往会出现问题。

Date最适合存储日期对象。它是持久化的，序列化的…

日历是操作日期的最佳工具。

注意:我们有时也更喜欢java.lang.Long而不是Date，因为Date是可变的，因此不是线程安全的。在Date对象上，使用setTime()和getTime()在两者之间切换。例如，应用程序中的一个常量Date(例如:0 1970/01/01，或应用程序的END_OF_TIME，您设置为2099/12/31;这些对于替换null值作为开始时间和结束时间非常有用，特别是当您在数据库中持久化它们时，因为SQL对null非常特殊)。

对于新代码(如果您的策略允许第三方代码)，最好的方法是使用Joda Time库。

日期和日历都有很多设计问题，它们都不是新代码的好解决方案。