1. Introduction
The LocalDateTime class from Java 8 is an immutable and thread-safe object that represents a date-time. In this article we will focus on how to format LocalDateTime using a custom pattern.
2. Using DateTimeFormatter class
The DateTimeFormatter is a class for printing and parsing date-time objects.
In the following example we use custom pattern to parse LocalDateTime using DateTimeFormatter class:
package com.frontbackend.datetime;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class DateTimeFormatterTest {
public static void main(String[] args) {
// Get current datetime
LocalDateTime currentDateTime = LocalDateTime.now();
// Get DateTimeFormatter instance of custom pattern
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm");
// Format datetime using DateTimeFormatter
String formatDateTime = currentDateTime.format(formatter);
System.out.println(formatDateTime);
}
}
The program produces the following output:
2022-04-20 23:45
In this example:
- first we created new instance of
LocalDateTime- that represents current date time, - in the next step we use
ofPattern(...)method onDateTimeFormatterto create custom formatter class, - finally, we format
LocalDateTimeusingDateTimeFormatter.
We could also use inbuild DateTimeFormatter instances:
Formatter Description Example
------- ------- -------
BASIC_ISO_DATE Basic ISO date '20111203'
ISO_LOCAL_DATE ISO Local Date '2011-12-03'
ISO_OFFSET_DATE ISO Date with offset '2011-12-03+01:00'
ISO_DATE ISO Date with or without offset '2011-12-03+01:00'; '2011-12-03'
ISO_LOCAL_TIME Time without offset '10:15:30'
ISO_OFFSET_TIME Time with offset '10:15:30+01:00'
ISO_TIME Time with or without offset '10:15:30+01:00'; '10:15:30'
ISO_LOCAL_DATE_TIME ISO Local Date and Time '2011-12-03T10:15:30'
ISO_OFFSET_DATE_TIME Date Time with Offset '2011-12-03T10:15:30+01:00'
ISO_ZONED_DATE_TIME Zoned Date Time '2011-12-03T10:15:30+01:00[Europe/Paris]'
ISO_DATE_TIME Date and time with ZoneId '2011-12-03T10:15:30+01:00[Europe/Paris]'
ISO_ORDINAL_DATE Year and day of year '2012-337'
ISO_WEEK_DATE Year and Week '2012-W48-6'
ISO_INSTANT Date and Time of an Instant '2011-12-03T10:15:30Z'
RFC_1123_DATE_TIME RFC 1123 / RFC 822 'Tue, 3 Jun 2008 11:05:30 GMT'
In the following example we are using inbuilt DateTimeFormatter instance:
package com.frontbackend.datetime;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class DateTimeFormatterTest {
public static void main(String[] args) {
// Get current datetime
LocalDateTime currentDateTime = LocalDateTime.now();
// Format LocalDateTime using inbuilt formatters
System.out.println(currentDateTime.format(DateTimeFormatter.ISO_LOCAL_DATE));
System.out.println(currentDateTime.format(DateTimeFormatter.ISO_LOCAL_TIME));
System.out.println(currentDateTime.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME));
System.out.println(currentDateTime.format(DateTimeFormatter.ISO_WEEK_DATE));
System.out.println(currentDateTime.format(DateTimeFormatter.ISO_ORDINAL_DATE));
System.out.println(currentDateTime.format(DateTimeFormatter.BASIC_ISO_DATE));
}
}
Output:
2022-04-21
00:08:00.114
2022-04-21T00:08:00.114
2022-W16-4
2022-111
20220421
The list of common Patterns for Formatting and Parsing DateFormatter:
Symbol Meaning Presentation Examples
------ ------- ------------ -------
G era text AD; Anno Domini; A
u year year 2004; 04
y year-of-era year 2004; 04
D day-of-year number 189
M/L month-of-year number/text 7; 07; Jul; July; J
d day-of-month number 10
Q/q quarter-of-year number/text 3; 03; Q3; 3rd quarter
Y week-based-year year 1996; 96
w week-of-week-based-year number 27
W week-of-month number 4
E day-of-week text Tue; Tuesday; T
e/c localized day-of-week number/text 2; 02; Tue; Tuesday; T
F week-of-month number 3
a am-pm-of-day text PM
h clock-hour-of-am-pm (1-12) number 12
K hour-of-am-pm (0-11) number 0
k clock-hour-of-am-pm (1-24) number 0
H hour-of-day (0-23) number 0
m minute-of-hour number 30
s second-of-minute number 55
S fraction-of-second fraction 978
A milli-of-day number 1234
n nano-of-second number 987654321
N nano-of-day number 1234000000
Java example program that used custom patterns for formatting LocalDateTime:
package com.frontbackend.datetime;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class DateTimeFormatterTest {
public static void main(String[] args) {
// Get current datetime
LocalDateTime currentDateTime = LocalDateTime.now();
// Format LocalDateTime using inbuilt formatters
System.out.println(currentDateTime.format(DateTimeFormatter.ofPattern("yyyy-MM-dd")));
System.out.println(currentDateTime.format(DateTimeFormatter.ofPattern("HH:mm:ss")));
System.out.println(currentDateTime.format(DateTimeFormatter.ofPattern("EEE, MMM d, ''yy")));
System.out.println(currentDateTime.format(DateTimeFormatter.ofPattern("h:mm a")));
System.out.println(currentDateTime.format(DateTimeFormatter.ofPattern("EEE, d MMM yyyy HH:mm:ss")));
}
}
The output:
2022-04-21
00:17:39
Thu, Apr 21, '22
12:17 AM
Thu, 21 Apr 2022 00:17:39
3. Conclusion
In this article, we presented how to format LocalDateTime in Java 8. The DateTimeFormatter was designed for that job. Note that DateTimeFormatteris immutable and thread-safe. This object is perfect as a static final constant in a class where it will be used.
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