Convert java.util.Date to String

java

date-formatting

java-date

simpledateformat

byAnton Shumikhin·Jan 5, 2025

To transform java.util.Date to a String in Java, use the handy-dandy SimpleDateFormat class. Supply your required date format pattern to its constructor, and format the date instance. Here's a quick 'n' dirty example:

// The Date Whisperer takes the stage 🎩
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
// Presto-change-o magic to transform today's date into string! 🪄✨
String formattedDate = formatter.format(new Date());
// Tada! 🎉  Prints the date in yyyy-MM-dd format
System.out.println(formattedDate);

Voila! It outputs the date in yyyy-MM-dd format.

Demystifying date and time patterns

To shape a Date into a String using SimpleDateFormat, it's important to know how to dance with date and time patterns. For instance, the combo motion "yyyy-MM-dd HH:mm:ss" spins a standard timestamp format spinning year, month, day, hours, minutes, and seconds together.

Tackling timezones and localization

Heads up, fellow coders! SimpleDateFormat famously doesn't work well with others (not thread-safe), hence it's always prudent to handle instances like eggs on a spoon race when used in a multi-threaded environment. Remember to be alert about time zones and locale settings:

// I've got time zones on my mind, and my mind on time zones 🌐
SimpleDateFormat sdfWithTimezone = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.US);
sdfWithTimezone.setTimeZone(TimeZone.getTimeZone("GMT"));
// It's Time Zone O'Clock somewhere in the world 👀
String formattedDate = sdfWithTimezone.format(yourDate);

Road not taken: Alternatives to SimpleDateFormat

For those trodding along the Apache Commons Lang path, here's your mantra:

// "If not SimpleDateFormat, then DateFormatUtils", said a wise Java coder once. 🦉
String formattedDate = DateFormatUtils.format(yourDate, "yyyy-MM-dd HH:mm:ss");

If you're on board the Java 8 or beyond express 🚄, befriend the DateTimeFormatter:

// Glance at how we replace 'Simple' with 'Time' here. It's not just semantics; it's evolution. 🦖🦕
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
String formattedDate = yourDate.toInstant()
                               .atZone(ZoneId.systemDefault())
                               .format(formatter);

This takes care of your fractional seconds nightmare and ensures peaceful sleep in multi-threaded scenarios.

Journey back in time: Ensuring backward compatibility

Working with older relics like Java (6/7) or Android? Fear not! Hop onboard the ThreeTen-Backport or ThreeTenABP time machines, which backport the java.time to these versions.

// The Back to the Future of Java date formatting starts here. 😎
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
String formattedDate = DateTimeUtils.toDate(yourDate.toInstant()).format(formatter);

Digging deeper: Advanced scenarios

Defusing the thread bomb

Thread safety is an issue with SimpleDateFormat, but luckily, java.time classes or DateTimeFormatter in Java 8 and onwards play nicely in a multi-threaded environment. Deny the drama, use them!

Database havoc

Interaction with JDBC or databases can involve converting a String back to a Date. Consistent patterns during conversion are a must to avoid playing Russian roulette with your data.