How to Convert Java Date to a UTC String Representation?

How can I efficiently convert a java.util.Date object into a String formatted in UTC?

final Date date = new Date();
final String ISO_FORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSS zzz";
final SimpleDateFormat sdf = new SimpleDateFormat(ISO_FORMAT);
final TimeZone utc = TimeZone.getTimeZone("UTC");
sdf.setTimeZone(utc);
System.out.println(sdf.format(date));

To create a String representation of a `java.util.Date` in UTC format, the preferred approach involves utilizing the `SimpleDateFormat` class while setting the time zone to UTC. This method allows for better control of the date formatting and ensures that the date is accurately represented in Coordinated Universal Time (UTC).

public static String formatDateToUTC(Date date) {
    final String ISO_FORMAT = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";
    final SimpleDateFormat sdf = new SimpleDateFormat(ISO_FORMAT);
    sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
    return sdf.format(date);
}

Causes

• Demand for UTC timestamps in logging for universally readable formats.
• Need for sortable date strings for data export.
• Interoperability with external APIs requiring UTC dates.

Solutions

• Use `SimpleDateFormat` with UTC time zone setting.
• Consider using `java.time` package for easier date and time manipulations.
• Employ a utility method to simplify repeated date formatting tasks.

Mistake: Forgetting to set the time zone to UTC in the SimpleDateFormat instance.

Solution: Always ensure to set the time zone using sdf.setTimeZone(TimeZone.getTimeZone("UTC"));.

Mistake: Using the default toString() method of Date which is locale-dependent and may not be in UTC.

Solution: Avoid using Date's toString() method; craft your own date formatting function.