How to get the current date/time in Java

Time zone handling

Broadening your horizons? Here's how to get date-time specifics for different zones:

import java.time.ZonedDateTime;
import java.time.ZoneId;

ZonedDateTime nowInParis = ZonedDateTime.now(ZoneId.of("Europe/Paris"));
System.out.println(nowInParis); // Voila! You are virtually in Paris.
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Tracking precise moments

When every millisecond counts, Instant.now() offers timestamp precision. It's the Java equivalent of a high-speed camera:

import java.time.Instant;

Instant timestamp = Instant.now();
System.out.println(timestamp); // Laser accurate timestamp in UTC. No kidding!
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Count from the epoch

For those retro folks who prefer counting seconds from the epoch, System.currentTimeMillis() is Java's built-in time machine:

long millis = System.currentTimeMillis();
System.out.println(millis); // Prints the milliseconds from the epoch. Cool, right?
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Farewell to the old

Embrace java.time API when migrating from Joda-Time. java.time format offers modern API support with smoother maintenance and thread safety:

import java.time.format.DateTimeFormatter;

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMdd_HHmmss");
String formattedNow = now.format(formatter);
System.out.println(formattedNow); // Out with the old, in with the new.
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Practical examples

Need a custom formatted timestamp for file naming? DateTimeFormatter does the needful with a pattern of your choice:

String fileNameTimestamp = now.format(DateTimeFormatter.ofPattern("yyyy-MM-dd_HH-mm-ss"));
String fileName = "backup_" + fileNameTimestamp + ".zip";
// There's your file. Now zip it before it unformats!
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Database integration

Applications dealing with databases need Java's Database Connectivity. Luckily, JDBC 4.2 is here to save your day with direct java.time type operations:

PreparedStatement pstmt = con.prepareStatement("INSERT INTO events (occurrence) VALUES (?)");
pstmt.setObject(1, LocalDateTime.now());
pstmt.executeUpdate();
// Who knew inserting date and time could be this fun?
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The classics and the modern

For sturdy soldiers on Java 6 and 7, ThreeTen-Backport comes to your aid. For Android knights, ThreeTenABP ensures you enjoy the fruits of modern date and time API.

Best practices worth adopting

• Ensure to set time zones explicitly with ZoneId to say goodbye to disruptions.
• For capturing the date with correct time zone, use LocalDate.now(ZoneId).
• The java.time.Clock is your accomplice for testable, alternative time sources. Mock it, tweak it, test it!