IBM User Guide for Java V7 on Windows > Installing and configuring the SDK and Runtime Environment

Updating your SDK or JRE for daylight saving time changes

You can apply recent changes to daylight saving time using the IBM Time Zone Update Utility for Javaâ„¢ (JTZU).

Many countries around the world use a daylight saving time (DST) convention. Typically, clocks move forward by one hour during the summer months to create more daylight hours during the afternoon and less during the morning. This practice has many implications, including the need to adjust system clocks in computer systems. Occasionally, countries change their DST start and end dates. These changes can affect the date and time functions in applications, because the original start and end dates are programmed into the operating system and in Java software. To avoid this problem you must update operating systems and Java installations with the new DST information.

The Olson time zone database is an external resource that compiles information about the time zones around the world. This database establishes standard names for time zones, such as "America/New_York", and provides regular updates to time zone information that can be used as reference data. To ensure that Java JREs and SDKs contain up to date DST information, IBM incorporates the latest Olson update into each Java service refresh. To find out which Olson time zone update is included for a particular service refresh, see https://www.ibm.com/developerworks/java/jdk/dst/olson_table.html.

If a DST change has been introduced since the last service refresh, you can use JTZU to directly update your Java installation. You can also use this tool to update your installation if you are unable to move straight to the latest service refresh. JTZU is available from IBM developerWorks using the following link: https://www.ibm.com/developerworks/java/jdk/dst/jtzu.html.

Results

After updating your Java installation with any recent DST changes, your application can handle time and date calculations correctly.

Parent: Installing and configuring the SDK and Runtime Environment

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