How to set a JVM TimeZone Properly

Question

You can pass the JVM this param

-Duser.timezone

For example

-Duser.timezone=Europe/Sofia

and this should do the trick. Setting the environment variable TZ also does the trick on Linux.

You can also set the default time zone in your code by using following code.

TimeZone.setDefault(TimeZone.getTimeZone("UTC"));

To Yours

 TimeZone.setDefault(TimeZone.getTimeZone("Europe/Sofia"));

The accepted answer above:

-Duser.timezone="Europe/Sofia" 

Didn't work for me exactly. I only was able to successfully change my timezone when I didn't have quotes around the parameters:

-Duser.timezone=Europe/Sofia

On windows 7 and for JDK6, I had to add -Duser.timezone="Europe/Sofia" to the JAVA_TOOL_OPTIONS system variable located under "My computer=>Properties=>Advanced System Settings=>Environment Variables".

If you already have some other property set for JAVA_TOOL_OPTIONS just append a space and then insert your property string.

Two options that I don’t think were covered in the other answers:

Avoid the need

Whatever you do to set the JVM default time zone, it is very hard to make sure that no one else sets it differently. It can be set at any time without notice from another part of your program or from another program running in the same JVM. So in your time operations be explicit about which time zone you want, and you will always know what you get independently of the JVM setting. Example:

    System.out.println(ZonedDateTime.now(ZoneId.of("Asia/Dushanbe")));

Example output:

2018-10-11T14:59:16.742020+05:00[Asia/Dushanbe]

System.setProperty

For many purposes the following will not be the preferred way, and it can certainly be misused. For “throw away” programs I sometimes find it practical. You can also set a system property from within Java:

    System.setProperty("user.timezone", "Australia/Tasmania");
    System.out.println(ZonedDateTime.now());

This just printed:

2018-10-11T21:03:12.218959+11:00[Australia/Tasmania]

If you want validation of the string you are passing, use:

        System.setProperty("user.timezone", ZoneId.of("Australia/Tasmania").getId());

If you are using Maven:

mvn -Dexec.args="-Duser.timezone=Europe/Sofia ....."

Setting environment variable TZ should also works

ex: export TZ=Asia/Shanghai