Time Zone Setting

Use Cases

The local time of different countries and regions varies according to their longitude. Therefore, different time zones are planned. For example, the UK uses time zone 0 and China uses time zone GMT+8. The time in China is eight hours earlier than that in the UK. For example, 12:00 in Beijing is 4 a.m. in London. The time zone module allows your application to obtain the time zone list to implement its own service logic, for example, a dual-clock application.

How to Develop

Import the i18n module.
```
import I18n from '@ohos.i18n';
```

Create a TimeZone object and implement functions such as calculating the offset between a fixed time zone and the actual time zone and obtaining and traversing the time zone list.

// Obtain the time zone of Brazil.
let timezone = I18n.getTimeZone("America/Sao_Paulo"); // Pass in a specific time zone to create a TimeZone object.
let timezoneId = timezone.getID();// America/Sao_Paulo

// Obtain the TimeZone object corresponding to the city ID.
let timezone = I18n.TimeZone.getTimezoneFromCity("Auckland");
timezone.getID();// Pacific/Auckland

// Localized time zone name
let timeZoneName = timezone.getDisplayName("zh-Hans", true); // Brasilia Standard Time

// Localized city name
let cityDisplayName = I18n.TimeZone.getCityDisplayName("Auckland", "zh-Hans") // Auckland (New Zealand)

// Fixed offset of the time zone
let rawOffset = timezone.getRawOffset(); // -10800000

// Actual offset of the time zone (fixed offset + DST)
let offset = timezone.getOffset(1234567890);// -10800000

// List of time zone IDs supported by the system
let ids = I18n.TimeZone.getAvailableIDs() // ["America/Adak", "Asia/Hovd", "America/Sao_Paulo", "Asia/Jerusalem", "Europe/London",...]

// List of time zone city IDs supported by the system
let cityIdArray = I18n.TimeZone.getAvailableZoneCityIDs();  // ["Auckland", "Magadan", "Lord Howe Island",...]
// Traverse the list of time zone city IDs.
let timezoneList: Array<object> = []; // Time zone list displayed to the user
class Item {
    cityDisplayName : string = "";
    timezoneId : string = "";
    offset : string = "";
    cityId : string = ""
}
for (let i =0 ; i < cityIdArray.length ; i++) {
    let cityId = cityIdArray[i];
    let timezone = I18n.TimeZone.getTimezoneFromCity(cityId); // TimeZone object corresponding to the city ID
    let cityDisplayName = I18n.TimeZone.getCityDisplayName(cityId, "zh-CN"); // Localized city name
    let timestamp = (new Date()).getTime()
    let item : Item = {
        cityDisplayName : cityDisplayName,
        timezoneId : timezone.getID(),
        offset : 'GMT'+ (timezone.getOffset(timestamp) / 3600*1000),
        cityId : cityId 
    }
    timezoneList.push(item);
}

// TimeZone object array corresponding to the specified geographical coordinates
let timezoneArray = I18n.TimeZone.getTimezonesByLocation(-43.1, -22.5)
for (let i =0;i < timezoneArray.length; i++) {
    timezoneArray.getID(); // America/Sao_Paulo
}

Dual-Clock Application

Import the i18n module.

import I18n from '@ohos.i18n';
import Intl from '@ohos.intl';

Add a time zone to the preferred time zone list of the application.

let appPreferredTimeZoneList = [] // Preferred time zone list of the application
appPreferredTimeZoneList.push(timezone1);
appPreferredTimeZoneList.push(timezone2);

Traverse the preferred time zone list of the application to obtain the time of each time zone.

let locale = I18n.System.getSystemLocale();
for (let i = 0 ; i < appPreferredTimeZoneList.length ; i++) {
    let timezone = appPreferredTimeZoneList[i];
    let calendar = I18n.getCalendar(locale);
    calendar.setTimeZone(timezone); // Set the time zone of the Calendar object.
    // Obtain the year, month, day, hour, minute, and second.
    let year = calendar.get("year"); 
    let month = calendar.get("month");
    let day = calendar.get("date");
    let hour = calendar.get("hour");
    let minute = calendar.get("minute");
    let second = calendar.get("second");
}

Time Zone Setting

Use Cases

How to Develop

Time Zone-related Functions

Dual-Clock Application