时区显示值与给定时区的 GMT 偏移量? [英] Timezone display value with GMT offset from a given timezone?

问题描述

我想构建一个时区列表来显示给用户选择.显示名称必须是这样的:

I would like to construct a timezone list to show it to users to select. The display name has to be like:

( GMT 5:30 ) 印度标准时间(亚洲/加尔各答)

我正在使用 TimeZone.getAvailableIDs() 获取所有时区并构建列表.我写的代码是:

I am taking all timezones with TimeZone.getAvailableIDs() and constructing the list. The code I wrote is:

String[] timeZones = TimeZone.getAvailableIDs();
List<String> tzList = new ArrayList<String>();
for (String timeZone : timeZones)
{
  TimeZone tz = TimeZone.getTimeZone(timeZone);
  StringBuilder timeZoneStr = new StringBuilder();
  timeZoneStr.append("( GMT ").append(tz.getRawOffset() / (60 * 60 * 1000)).append(" ) ").append(tz.getDisplayName()).append("(").append(timeZone).append(")");
  tzList.add(timeZoneStr.toString());
  System.out.println(timeZoneStr.toString());
}

输出片段如下:

( GMT 5 ) Maldives Time(Indian/Maldives)
( GMT 5 ) Pakistan Time(PLT)
( GMT 5 ) India Standard Time(Asia/Calcutta)
( GMT 5 ) India Standard Time(Asia/Kolkata)
( GMT 5 ) India Standard Time(IST)

但我需要得到的输出是:

But the output I need to get is:

( GMT 5:0 ) Maldives Time(Indian/Maldives)
( GMT 5:0 ) Pakistan Time(PLT)
( GMT 5:30 ) India Standard Time(Asia/Calcutta)
( GMT 5:30 ) India Standard Time(Asia/Kolkata)
( GMT 5:30 ) India Standard Time(IST)

我该怎么做才能到达 5:30?

What should I do to get 5:30?

推荐答案

一个更具可读性的答案如下:

A more readable answer is the following:

for (String timeZone : timeZones) {
  TimeZone tz = TimeZone.getTimeZone(timeZone);

  long hours = TimeUnit.MILLISECONDS.toHours(tz.getRawOffset());
  long minutes = TimeUnit.MILLISECONDS.toMinutes(tz.getRawOffset())
      - TimeUnit.HOURS.toMinutes(hours);

  String timeZoneString = String.format("( GMT %d:%02d ) %s(%s)", hours,
      minutes, tz.getDisplayName(), timeZone);
  tzList.add(timeZoneString);
  System.out.println(timeZoneString);
}

这也可以正确显示，例如5:00 和 5:30.String.format() 的使用使得在阅读代码时更容易确定最终字符串.TimeUnit 类简化了数学.

This also correctly displays e.g. 5:00 and 5:30. The use of String.format() makes the final string easier to determine when reading the code. The use of the TimeUnit class simplifies the maths.

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