Date

[Date] 1 How to get current date time

The main API for dates, times, instants, and durations.

Posted by Mr.Vincent on 2021-07-13
Estimated Reading Time 7 Minutes
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In this tutorial, we will show you how to get the current date time from the new Java 8 java.time.* like Localdate, LocalTime, LocalDateTime, ZonedDateTime, Instant and also the legacy date time APIs like Date and Calendar.

Summary

  • For new Java 8 java.time.* APIs , we can use .now() to get the current date-time and format it with DateTimeFormatter.
  • For legacy date-time APIs, we can use new Date() and Calendar.getInstance() to get the current date-time and format it with SimpleDateFormat.

Get current date time in Java

The below are some code snippets to display the current date-time in Java.

For java.time.LocalDate, uses LocalDate.now().

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DateTimeFormatter dtf = DateTimeFormatter.ofPattern("uuuu/MM/dd");
LocalDate localDate = LocalDate.now();
System.out.println(dtf.format(localDate));            // 2021/03/22

For java.time.localTime, uses LocalTime.now().

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DateTimeFormatter dtf = DateTimeFormatter.ofPattern("HH:mm:ss");
LocalTime localTime = LocalTime.now();
System.out.println(dtf.format(localTime));            // 16:37:15

For java.time.LocalDateTime, uses LocalDateTime.now().

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DateTimeFormatter dtf = DateTimeFormatter.ofPattern("uuuu/MM/dd HH:mm:ss");
LocalDateTime now = LocalDateTime.now();
System.out.println(dtf.format(now));                  //  2021/03/22 16:37:15

For java.time.ZonedDateTime, uses ZonedDateTime.now().

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// get current date-time, with system default time zone
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("uuuu/MM/dd HH:mm:ss");
ZonedDateTime now = ZonedDateTime.now();
System.out.println(dtf.format(now));                  // 2021/03/22 16:37:15
System.out.println(now.getOffset());                  // +08:00

// get current date-time, with a specified time zone
ZonedDateTime japanDateTime = now.withZoneSameInstant(ZoneId.of("Asia/Tokyo"));
System.out.println(dtf.format(japanDateTime));        // 2021/03/22 17:37:15
System.out.println(japanDateTime.getOffset());        // +09:00

For java.time.Instant, uses Instant.now().

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Instant now = Instant.now();

// convert Instant to ZonedDateTime
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("uuuu/MM/dd HH:mm:ss");
ZonedDateTime zonedDateTime = ZonedDateTime.ofInstant(now, ZoneId.systemDefault());
System.out.println(dtfDateTime.format(zonedDateTime));

For java.util.Date, uses new Date().

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DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date = new Date();
System.out.println(dateFormat.format(date));           // 2021/03/22 16:37:15

For java.util.Calendar, uses Calendar.getInstance().

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DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Calendar cal = Calendar.getInstance();
System.out.println(dateFormat.format(cal.getTime()));  // 2021/03/22 16:37:15

java.time.LocalDate

For the java.time.LocalDate, uses LocalDate.now() to get the current date without a time-zone, and format it with the DateTimeFormatter.

Example: LocalDate

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package com.mkyong.app;

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

public class LocalDateExample {
  public static void main(String[] args) {
      DateTimeFormatter dtf = DateTimeFormatter.ofPattern("uuuu/MM/dd");
      LocalDate localDate = LocalDate.now();
      System.out.println(dtf.format(localDate));    // 2021/03/22
  }
}

java.time.LocalTime

For the java.time.LocalTime, uses LocalDate.now() to get the current time without a time-zone, and format it with the DateTimeFormatter.

Example: LocalTime

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package com.mkyong.app;

import java.time.LocalTime;
import java.time.format.DateTimeFormatter;

public class LocalTimeExample {
    public static void main(String[] args) {
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("HH:mm:ss");
        LocalTime localTime = LocalTime.now();
        System.out.println(dtf.format(localTime));    // 16:37:15
    }
}

java.time.LocalDateTime

For java.time.LocalDateTime, uses LocalDateTime.now() to get the current date time without a time-zone, and format it with the DateTimeFormatter.

Example: LocalDateTime

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package com.mkyong.app;

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

public class LocalDateTimeExample {
    public static void main(String[] args) {
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("uuuu/MM/dd HH:mm:ss");
        LocalDateTime now = LocalDateTime.now();
        System.out.println(dtf.format(now));        //  2021/03/22 16:37:15
    }
}

java.time.ZonedDateTime

For java.time.ZonedDateTime, uses ZonedDateTime.now() to get the current date time with the system default time zone, or a specified time zone.

Example: ZonedDateTime

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package com.mkyong.app;

import java.time.OffsetDateTime;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;

public class ZonedDateTimeExample {
  public static void main(String[] args) {
      DateTimeFormatter dtf = DateTimeFormatter.ofPattern("uuuu/MM/dd HH:mm:ss");

      // Get default time zone
      System.out.println(ZoneOffset.systemDefault());         // Asia/Kuala_Lumpur
      System.out.println(OffsetDateTime.now().getOffset());   // +08:00

      // get current date time, with +08:00
      ZonedDateTime now = ZonedDateTime.now();
      System.out.println(dtf.format(now));                    // 2021/03/22 16:37:15
      System.out.println(now.getOffset());                    // +08:00

      // get get current date time, with +09:00
      ZonedDateTime japanDateTime = now.withZoneSameInstant(ZoneId.of("Asia/Tokyo"));
      System.out.println(dtf.format(japanDateTime));          // 2021/03/22 17:37:15
      System.out.println(japanDateTime.getOffset());          // +09:00
  }
}

java.time.Instant

For java.time.Instant, uses Instant.now() to get the seconds passed since the Unix epoch time (midnight of January 1, 1970 UTC), and later convert to other java.time.* date time classes like LocalDate, LocalDateTime and ZonedDateTime.

Example: Instant

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package com.mkyong.app;

import java.time.*;
import java.time.format.DateTimeFormatter;

public class InstantExample {
  private static final DateTimeFormatter dtfDate = DateTimeFormatter.ofPattern("uuuu/MM/dd");
  private static final DateTimeFormatter dtfTime = DateTimeFormatter.ofPattern("HH:mm:ss");
  private static final DateTimeFormatter dtfDateTime = DateTimeFormatter.ofPattern("uuuu/MM/dd HH:mm:ss");
  public static void main(String[] args) {
      // seconds passed since the Unix epoch time (midnight of January 1, 1970 UTC)
      Instant now = Instant.now();

      // convert Instant to LocalDate
      LocalDate localDate = LocalDate.ofInstant(now, ZoneId.systemDefault());
      System.out.println(dtfDate.format(localDate));            // 2021/03/22

      // convert Instant to localTime
      LocalTime localTime = LocalTime.ofInstant(now, ZoneId.systemDefault());
      System.out.println(dtfTime.format(localTime));            // 16:37:15

      // convert Instant to LocalDateTime
      LocalDateTime localDateTime = LocalDateTime.ofInstant(now, ZoneId.systemDefault());
      System.out.println(dtfDateTime.format(localDateTime));    // 2021/03/22 16:37:15

      // convert Instant to ZonedDateTime
      ZonedDateTime zonedDateTime = ZonedDateTime.ofInstant(now, ZoneId.systemDefault());
      System.out.println(dtfDateTime.format(zonedDateTime));    // 2021/03/22 16:37:15
  }
}

java.util.Date (Legacy)

For the legacy java.util.Date, uses new Date() or new Date(System.currentTimeMillis() to get the current date time, and format it with the SimpleDateFormat.

Example: Date

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package com.mkyong.app;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

public class DateExample {
  public static void main(String[] args) {
      DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");

      Date date = new Date();
      System.out.println(dateFormat.format(date));    // 2021/03/22 16:37:15

      // new Date() actually calls this new Date(long date)
      Date date2 = new Date(System.currentTimeMillis());
      System.out.println(dateFormat.format(date));    // 2021/03/22 16:37:15
  }
}

java.util.Calendar (Legacy)

For the legacy java.util.Calendar, uses Calendar.getInstance() to get the current date time, and format it with the SimpleDateFormat.

Example: Calendar

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package com.mkyong.app;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;

public class CalendarExample {
  public static void main(String[] args) {
      DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
      Calendar cal = Calendar.getInstance();
      System.out.println(dateFormat.format(cal.getTime()));   // 2021/03/22 16:37:15
  }
}

References：https://mkyong.com/java/java-how-to-get-current-date-time-date-and-calender/

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