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<TITLE>Converting Times Between Time Zones (Java Developers Almanac Example)
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<h3>e372. Converting Times Between Time Zones</h3>
There is a convenient <code>setTimeZone()</code> method in the <code>Calendar</code> object.
However, it doesn't always return the correct results when used after
a calendar field is set. This example demonstrates a more reliable way
to convert a specific time from one time zone to another. It involves
creating two <code>Calendar</code> instances and transfering the UTC (Coordinate
Universal Time) from one to the other. The UTC is a representation of
time and date that is independent of time zones.
<pre> // Given a local time of 10am, get the time in Japan
// Create a Calendar object with the local time zone
Calendar local = new GregorianCalendar();
local.set(Calendar.HOUR_OF_DAY, 10); // 0..23
local.set(Calendar.MINUTE, 0);
local.set(Calendar.SECOND, 0);
// Create an instance using Japan's time zone and set it with the local UTC
Calendar japanCal = new GregorianCalendar(TimeZone.getTimeZone(<font color="#0066ff"><i>"Japan"</i></font>));
japanCal.setTimeInMillis(local.getTimeInMillis());
// Get the foreign time
int hour = japanCal.get(Calendar.HOUR); // 3
int minutes = japanCal.get(Calendar.MINUTE); // 0
int seconds = japanCal.get(Calendar.SECOND); // 0
boolean am = japanCal.get(Calendar.AM_PM) == Calendar.AM; //true
// Given a time of 10am in Japan, get the local time
japanCal = new GregorianCalendar(TimeZone.getTimeZone(<font color="#0066ff"><i>"Japan"</i></font>));
japanCal.set(Calendar.HOUR_OF_DAY, 10); // 0..23
japanCal.set(Calendar.MINUTE, 0);
japanCal.set(Calendar.SECOND, 0);
// Create a Calendar object with the local time zone and set
// the UTC from japanCal
local = new GregorianCalendar();
local.setTimeInMillis(japanCal.getTimeInMillis());
// Get the time in the local time zone
hour = local.get(Calendar.HOUR); // 5
minutes = local.get(Calendar.MINUTE); // 0
seconds = local.get(Calendar.SECOND); // 0
am = local.get(Calendar.AM_PM) == Calendar.AM; // false
</pre>
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<b>Related Examples</b></font></td>
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e369. <a class="eglink" href="GetCurTime.html?l=rel">
Getting the Current Time
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e370. <a class="eglink" href="GetTimeOtherZone.html?l=rel">
Getting the Current Time in Another Time Zone
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e371. <a class="eglink" href="GetAllZones.html?l=rel">
Retrieving Information on All Available Time Zones
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See also:
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Arrays">
Arrays
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Bits">
Bits
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Collections">
Collections
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Dates">
Dates
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Hash%20Tables">
Hash Tables
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Lists">
Lists
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Property%20Files">
Property Files
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Sets">
Sets
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Sorted%20Collections">
Sorted Collections
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<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Timers">
Timers
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