- Cst Daylight Savings Time Change
- Does Cst Change For Daylight Savings
- Utc Daylight Time
- Gmt Vs Utc Daylight Savings
Central Standard Time (CST) is UTC-6:00, and Central Daylight Time (CDT) is UTC-5:00, this time zone is called Central Time Zone (CT) in the United States, Canada, Mexico, Central America, Caribbean Islands, and part of the Eastern Pacific Ocean. Support daylight saving time (DST) or summer time. This is adapted from a mail I used to use at work to inform co-workers about the change in a semi-weekly meeting. I have modified it to use UTC where I previously used GMT. From March 11, 2018 to November 3, 2018, it meant UTC-4. And from November 4, 2018 to December 31, 2018, it's UTC-5 again. But it gets worse. From Wikipedia: The Uniform Time Act of 1966 ruled that daylight saving time would run from the last Sunday of April until the last Sunday in October in the United States. CDT (Central Daylight Time) is one of the well-known names of UTC-5 time zone which is 5h. Behind of UTC (Coordinated Universal Time).The time offset from UTC can be written as -05:00. It's used as a DST (summer daylight saving time).During the winter, CST - Central Standard Time (UTC-6) is in use. Some locations use CST all year long.
Daylight Saving Time, or DST, is a practice of advancing clocks during summer months in order to leverage an additional hour of the natural light (saving heating power, illumination power, enhancing the mood, and so on).
It's used by several countries and needs to be taken into account when working with dates and timestamps.
In this tutorial, we'll see how to correctly handle DST in Java according to different locations.
2. JRE and DST Mutability
First, it's extremely important to understand that worldwide DST zones change very often and there's no central authority coordinating it.
A country, or in some cases even a city, can decide if and how to apply or revoke it.
Everytime it happens, the change is recorded in the IANA Time Zone Database, and the update will be rolled out in a future release of the JRE.
In case it's not possible to wait, we can force the modified Time Zone data containing the new DST settings into the JRE through an official Oracle tool called Java Time Zone Updater Tool, available on the Java SE download page. Jiffy lube on the spot renewal locations.
3. The Wrong Way: Three-Letter Timezone ID
Back in the JDK 1.1 days, the API allowed three-letter time zone IDs, but this led to several problems.
First, this was because the same three-letter ID could refer to multiple time zones. For example, CST could be U.S. “Central Standard Time”, but also “China Standard Time”. The Java platform could then only recognize one of them.
Another issue was that Standard timezones never take Daylight Saving Time into an account. Multiple areas/regions/cities can have their local DST inside the same Standard time zone, so the Standard time doesn't observe it.
Due to backward compatibility, it's still possible to instantiate a java.util.Timezone with a three-letter ID. However, this method is deprecated and shouldn't be used anymore.
4. The Right Way: TZDB Timezone ID
The right way to handle DST in Java is to instantiate a Timezone with a specific TZDB Timezone ID, eg. “Europe/Rome”.
Then, we'll use this in conjunction with time-specific classes like java.util.Calendar to get a proper configuration of the TimeZone's raw offset (to the GMT time zone), and automatic DST shift adjustments.
Let's see how the shift from GMT+1 to GMT+2 (which happens in Italy on March 25, 2018, at 02:00 am) is automatically handled when using the right TimeZone:
As we can see, ZONE_OFFSET is 60 minutes (because Italy is GMT+1) while DST_OFFSET is 0 at that time.
Let's add ten minutes to the Calendar:
Now DST_OFFSET has become 60 minutes too, and the country has transitioned its local time from CET (Central European Time) to CEST (Central European Summer Time) which is GMT+2:
If we display the two dates in the console, we'll see the time zone change as well:
As a final test, we can measure the distance between the two Dates, 1:55 and 3:05:
As we'd expect, the distance is of 10 minutes instead of 70.
We've seen how to avoid falling into the common pitfalls that we can encounter when working with Date through the correct usage of TimeZone and Locale.
5. The Best Way: Java 8 Date/Time API
Working with these thread-unsafe and not always user-friendly java.util classes have always been tough, especially due to compatibility concerns which prevented them from being properly refactored.
For this reason, Java 8 introduced a brand new package, java.time, and a whole new API set, the Date/Time API. This is ISO-centric, fully thread-safe and heavily inspired by the famous library Joda-Time.
Let's take a closer look at this new classes, starting from the successor of java.util.Date, java.time.LocalDateTime:
We can observe how a LocalDateTime is conforming to the ISO8601 profile, a standard and widely adopted date-time notation.
It's completely unaware of Zones and Offsets, though, that's why we need to convert it into a fully DST-aware java.time.ZonedDateTime:
As we can see, now the date incorporates two fundamental trailing pieces of information: +01:00 is the ZoneOffset, while [Europe/Rome] is the ZoneId.
Like in the previous example, let's trigger DST through the addition of ten minutes:
Again, we see how both the time and the zone offset are shifting forward, and still keeping the same distance:
We've seen what Daylight Saving Time is and how to handle it through some practical examples in different versions of Java core API.
When working with Java 8 and above, the usage of the new java.time package is encouraged thanks to the ease of use and to its standard, thread-safe nature.
As always, the full source code is available over on Github.
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Time zone abbreviations can be confusing, especially if you aren’t already familiar with the various time zones they represent. If you’re wondering about the abbreviation for Eastern Standard Time (EST) or need to know what UTC means, this handy guide will help.
Cst Daylight Savings Time Change
UTC and GMT: The Prime Meridian
UTC stands for Coordinated Universal Time. This is the world’s standard for regulating clocks and referring to other time zones. Also known as Greenwich Mean Time or GMT, it represents 0° in longitude or the Prime Meridian. The following cities are on or near the Prime Meridian and use UTC or GMT for their time zones:
- London, United Kingdom
- Accra, Ghana
- Valencia, Spain
- Bordeaux, France
Every other time zone represents an adjustment from UTC or GMT in terms of hours before or after it using minus or plus symbols, respectively.
Common World Time Zone Abbreviations
The following list includes some of the most common time zone abbreviations used around the world. Since some countries have their own abbreviations and names for time zones, you’ll find that there’s some overlap between zones.
AEST - Australia Eastern Standard Time
AEST stands for Australia Eastern Standard Time and is UTC +10:00. It’s in use in the eastern portion of Australia. Cities in this time zone include Brisbane and Sydney.
ACST - Australia Central Standard Time
ACST is the abbreviation for Australia Central Standard Time. ACST is UTC +09:30. This time zone represents the central portion of Australia, including the cities of Adelaide and Darwin.
AFT - Afghanistan Time
The country of Afghanistan uses the time zone of Afghanistan Time, which has the abbreviation AFT. This is UTC +04:30.
AKST - Alaska Standard Time
The abbreviation AKST stands for Alaska Standard Time. This time zone is in use in the state of Alaska and is UTC -09:00. During daylight savings time, it changes to AKDT for Alaska Daylight Time.
AST - Atlantic Standard Time
Atlantic Standard Time, abbreviated AST, is a time zone used by several countries. AST is UTC -04:00. During daylight savings time, this time zone is ADT or Atlantic Daylight Time. A few of the places using AST include the following:
- Antigua and Barbuda
- US Virgin Islands
AWST - Australia Western Standard Time
AWST stands for Australia Western Standard Time and is UTC +09:00. AWST is in use in the western portion of Australia, like in the city of Perth.
Does Cst Change For Daylight Savings
CAT - Central Africa Time
Central Africa Time is abbreviated as CAT. This time zone is UTC +02:00 and is in use in the following countries:
CET - Central European Time
Central European Time, abbreviated as CET, is used in a number of countries in Europe. It is UTC +01:00. In countries that observe daylight savings, the time zone changes to CEST for Central European Summer Time or CEDT for Central European Daylight Time. A few of the places using CET include the following:
CST - Central Standard Time
In use in the center portion of the United States and Canada, Central Standard Time is abbreviated CST. It is UTC -06:00. During daylight savings time, it changes to CDT or Central Daylight Time. This covers cities like Houston, Mexico City and Winnipeg.
EAT - East Africa Time
In the Eastern portion of Africa, several countries use EAT to abbreviate East Africa Time. EAT is UTC +03:00. It’s in use in the following places:
EET - Eastern European Time
EET is an abbreviation for Easter European Time. EET is UTC +02:00. In countries observing daylight savings time, it changes to EEDT for Eastern European Daylight Time or EEST for Eastern European Summer Time. Countries using EET include the following:
EST - Eastern Standard Time
Much of eastern North America uses EST to abbreviate Eastern Standard Time. This time zone is UTC -05:00. During daylight savings time, it changes to EDT for Eastern Daylight Time. Notable cities include New York, Toronto and Atlanta, as well as Nassau, Lima and Panama City.
Utc Daylight Time
MSK - Moscow Standard Time
MSK is the abbreviation for Moscow Standard Time. MSK is UTC +03:00. In summer, this becomes MSD or Moscow Summer Time. This time zone is in use in the following countries:
- Parts of Russia
- Parts of Ukraine
MST - Mountain Standard Time
Covering the central and some of the western portions of North America, Mountain Standard Time is abbreviated as MST. It is UTC -07:00. During daylight savings time, this becomes, MDT or Mountain Daylight Time. Cities here include Denver, Phoenix and Calgary.
PST - Pacific Standard Time
The western portion of North America is in PST or Pacific Standard Time. PST is UTC -08:00. It becomes PDT or Pacific Daylight Time during daylight savings time. Cities that observe PST include Vancouver, Los Angeles and Las Vegas.
WAT - West Africa Time
Many of the countries in West Africa use the time zone of West Africa Time. It is abbreviated as WAT. WAT is UTC +01:00. Some of the countries using West Africa Time include the following:
WET - Western European Time
WET is the abbreviation for Western European Time. This is UTC 00:00. During daylight savings time, it can be abbreviated as WEDT for Western European Daylight Time or WEST for Western European Summer Time. The following countries use WET:
- United Kingdom
Gmt Vs Utc Daylight Savings
DST - Daylight Savings Time
Many countries observe Daylight Saving Time, which has the abbreviation of DST. This is the practice of moving clocks one hour ahead in the spring to extend daylight hours during convenient times for workers.
Understanding Time Zones Helps You Communicate
When you’re communicating with people from other countries, it’s helpful to know a bit about the time zones, common abbreviations, and which countries are included. This is a small part of understanding other cultures.