使用java转换日期更快的时区 [英] Converting timezone for date faster using java

问题描述

我已经写了这个方法来转换日期时区。如何进一步减少此方法的执行时间。

I have written this method for converting a date time zone. How do i reduce the execution time of this method further.

public static Timestamp convertTimeZone(final Timestamp fromDate, final TimeZone fromTZ, final TimeZone toTZ ){
   Long timeInDate  =  fromDate.getTime() ;
   int fromOffset = fromTZ.getOffset(timeInDate);
   int toOffset = toTZ.getOffset(timeInDate);
   Timestamp dateStamp = new Timestamp(fromDate.getTime());

   if (fromOffset >= 0){
      int diff = 0;

      if (toOffset > 0){
          diff = (fromOffset - toOffset);
      } else {
          diff = (fromOffset + Math.abs(toOffset));
      }

      long date = fromDate.getTime() - diff;
      dateStamp.setTime(date);
   } else {
      int diff = 0;

      if (toOffset > 0){
          diff = (Math.abs( fromOffset) + toOffset);
      } else {
          diff = (Math.abs( fromOffset) - Math.abs(toOffset));
      }

      long date = fromDate.getTime() + diff;
      dateStamp.setTime(date);
   }

   return dateStamp;
}

推荐答案

使用 joda-time 可能如下所示：

DateTime dt = new DateTime(DateTimeZone.forID("GMT"));
System.out.println(dt); // 5 am
dt = dt.withZone(DateTimeZone.forID("EET"));
System.out.println(dt); // 8 am

请注意， Timestamp 没有时区的概念，所以它不适合代表它。

Note that Timestamp has no notion of Timezone so it is not suitable for representing it.

您的解决方案将具有良好的运行时间，因为它是O（1）。很难阅读。

Your solution will have a good running time, since it's O(1). It's harder to read though.

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