# Setting Default TimeZone in Spring Boot Application

# Introduction

Sometimes, we want to be able to specify the TimeZone used by an application. For a service running globally, this could mean that all servers are posting events using the same TimeZone, no matter their location.

# How it Works

The default value for *TimeZone* is typically based on the operating system of the machine where the JVM is running. We can change this:

-   By passing JVM arguments, using the *user.timezone* argument, in different ways depending on weather we run a task or a JAR
-   Programmatically, using the bean lifecycle configuration options (during/before creation of beans) or even inside a class, during execution

# Approaches

## Setting TimeZone on bootRun Task

If we use the *bootRun* task to run the application, we can pass the default *TimeZone* using JVM arguments in the command line. In this case, the value we set is available from the very beginning of the execution:
```
mvn spring-boot:run -Dspring-boot.run.jvmArguments="-Duser.timezone=Australia/Sydney"
```

## Setting TimeZone on JAR Execution

Similar to running the bootRun task, we can pass the default TimeZone value in the command line when executing the JAR file. The value we set is available from the very beginning of the execution:

```
java -Duser.timezone=Australia/Sydney -jar my-spring-app-0.0.1-SNAPSHOT.jar
```

## Setting Default TimeZone on Spring Boot Startup

Main Method
-------------------------------------------------

```
package com.cloudtuned;

@SpringBootApplication
public class MainApplication {

    public static void main(String[] args) {
        TimeZone.setDefault(TimeZone.getTimeZone("GMT+08:00"));

        SpringApplication.run(MainApplication.class, args);
    }
}

```

BeanFactoryPostProcessor
-------------------------------------------------

```
package com.cloudtuned;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import java.util.TimeZone;

@Component
public class TimeZoneConfig {

    private static final Logger LOGGER = LoggerFactory.getLogger(TimeZoneConfig.class);

    @PostConstruct
    public void init() {
        // Set the JVM default timezone
        TimeZone.setDefault(TimeZone.getTimeZone("Europe/Stockholm"));
        LOGGER.info(String.format("Timezone set to %s", TimeZone.getDefault().getID()));
    }
}

```

# Conclusion

In this article, we learned a number of ways of setting the default TimeZone in a Spring Boot Application.