How To Get All Supported Timzone IDs, Display Name and GMT Offset
Kushal Paudyal March 12th, 2010
Background:
TimeZone represents a time zone offset, and also figures out daylight savings. Typically, you get a TimeZone using getDefault which creates a TimeZone based on the time zone where the program is running. For example, for a program running in Japan, getDefault creates a TimeZone object based on Japanese Standard Time. You can also get a TimeZone using getTimeZone along with a time zone ID. For instance, the time zone ID for the U.S. Pacific Time zone is “America/Los_Angeles”. So, you can get a U.S. Pacific Time TimeZone object with:
TimeZone tz = TimeZone.getTimeZone(“America/Los_Angeles”);
You can use the getAvailableIDs method to iterate through all the supported time zone IDs. You can then choose a supported ID to get a TimeZone. If the time zone you want is not represented by one of the supported IDs, then a custom time zone ID can be specified to produce a TimeZone.
Code to print out all available timezones:
package com.kushal.utils.date;
/**
* @Author Kushal Paudyal
* www.sanjaal.com/java
* Last Modified On 2009-11-11
*
* ListAllAvailableTimeZones.java
*
* Prints our all the available timezones.
* Some logic added to format the output display.
*/
import java.util.Date;
import java.util.TimeZone;
public class ListAllAvailableTimeZones {
public static void main(String arg[]) {
printAvailableTimeZones();
}
/**
*
* This method will print all available timezones.
*
* The code that has been commented out was used to find
* maximum length of the timezone id and display name so
* that spaces can be padded to have a nice output.
*
*/
public static void printAvailableTimeZones()
{
/**
int maxTzNameLength=0;
int minTzNameLength=999;
int maxIdLength=0;
int minIdLength=999;
*/
Date date = new Date();
String TimeZoneIds[] = TimeZone.getAvailableIDs();
for (int i = 0; i < TimeZoneIds.length; i++) {
TimeZone tz = TimeZone.getTimeZone(TimeZoneIds[i]);
String tzName = tz.getDisplayName(tz.inDaylightTime(date),
TimeZone.LONG);
/**
if(tzName.length()>maxTzNameLength)
maxTzNameLength=tzName.length();
if(tzName.length() <minTzNameLength)
minTzNameLength=tzName.length();
if(TimeZoneIds[i].length()>maxIdLength)
maxIdLength=tzName.length();
if(TimeZoneIds[i].length() <minIdLength)
minIdLength=tzName.length();
*/
/**
* padding the timezoneid[i] with blankspaces for nice output.
* 32 was the maximum length of timezoneid[i]. So anything smaller
* will be padded with 32 - TimeZoneIds[i].length()
*
* for example, if a string TimeZoneIds[i] has a length of 27, we will pad
* 5 spaces.
*/
System.out.print(TimeZoneIds[i]
+ getBlankSpaces(32 - TimeZoneIds[i].length()) + ":");
/**Get the number of hours from GMT**/
int rawOffset = tz.getRawOffset();
int hour = rawOffset / (60 * 60 * 1000);
int minute = Math.abs(rawOffset / (60 * 1000)) % 60;
/**
* padding the name with blankspaces for nice output.
* 53 was the maximum length of tzName. So anything smaller
* will be padded with 53-tzName.lenghth()
*
* for example, if a timezone name length is 33, we will pad
* 20 spaces.
*/
tzName += getBlankSpaces(53 - tzName.length());
System.out.println(tzName + " " + "GMT" + (hour >= 0 ? "+" : "")
+ hour + ":" + minute);
}
/**
System.out.println("\n\nMax TzName Length "+maxTzNameLength);
System.out.println("Min TzName Length "+minTzNameLength);
System.out.println("\n\nMax ID Length "+maxIdLength);
System.out.println("Min ID Length "+minIdLength);
*/
}
/**
* @param length --> number of spaces required
* @return spaces
*
* Return a series of spaces according to length param.
*
* If you pass 5 as paramter, a string will 5 spaces will be returned.
*/
public static String getBlankSpaces(int length) {
String blankSpaces = "";
for (int i = 0; i < length; i++) {
blankSpaces += " ";
}
return blankSpaces;
}
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*
* THIS SOFTWARE IS NOT DESIGNED OR INTENDED FOR USE OR RESALE AS ON-LINE
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*/
}
Output of this program:
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Originally posted 2009-11-11 14:37:55.
