LocalDateTime format() method in Java

30 Nov, 2018
The format() method of LocalDateTime class in Java formats this date-time using the specified formatter.
Syntax:
public String format(DateTimeFormatter formatter)

Parameter: This method accepts a parameter formatter which specifies the formatter to use, not null.
Returns: The function returns the formatted date string and not null.
Below programs illustrate the LocalDateTime.format() method:
Program 1:
// Java program to illustrate the format() method  import java.util.*;import java.time.*;import java.time.format.DateTimeFormatter;  public class GfG {    public static void main(String[] args)    {        // Parses the date        LocalDateTime dt1            = LocalDateTime                  .parse("2018-11-03T12:45:30");          // Prints the date        System.out.println("Original LocalDateTime: "                           + dt1);          // Display d1 in different formats        // using format() method        System.out.println("BASIC_ISO_DATE format: "                           + (DateTimeFormatter.BASIC_ISO_DATE)                                 .format(dt1));        System.out.println("ISO_LOCAL_DATE format: "                           + (DateTimeFormatter.ISO_LOCAL_DATE)                                 .format(dt1));        System.out.println("ISO_DATE format: "                           + (DateTimeFormatter.ISO_DATE)                                 .format(dt1));        System.out.println("ISO_LOCAL_TIME format: "                           + (DateTimeFormatter.ISO_LOCAL_TIME)                                 .format(dt1));              }}
Original LocalDateTime: 2018-11-03T12:45:30
BASIC_ISO_DATE format: 20181103
ISO_LOCAL_DATE format: 2018-11-03
ISO_DATE format: 2018-11-03
ISO_LOCAL_TIME format: 12:45:30

Program 2:
// Program to illustrate the format() method  import java.util.*;import java.time.*;import java.time.format.DateTimeFormatter;  public class GfG {    public static void main(String[] args)    {        // Parses the date        LocalDateTime dt1            = LocalDateTime                  .parse("2016-09-06T12:45:30");          // Prints the date        System.out.println(dt1);          // Display d1 in different formats        // using format() method        System.out.println("ISO_TIME format: "                           + (DateTimeFormatter.ISO_TIME)                                 .format(dt1));        System.out.println("ISO_LOCAL_DATE_TIME format: "                           + (DateTimeFormatter.ISO_LOCAL_DATE_TIME)                                 .format(dt1));        System.out.println("ISO_DATE_TIME format: "                           + (DateTimeFormatter.ISO_DATE_TIME)                                 .format(dt1));        System.out.println("ISO_ORDINAL_DATE format: "                           + (DateTimeFormatter.ISO_ORDINAL_DATE)                                 .format(dt1));        System.out.println("ISO_WEEK_DATE format: "                           + (DateTimeFormatter.ISO_WEEK_DATE)                                 .format(dt1));    }}
2016-09-06T12:45:30
ISO_TIME format: 12:45:30
ISO_LOCAL_DATE_TIME format: 2016-09-06T12:45:30
ISO_DATE_TIME format: 2016-09-06T12:45:30
ISO_ORDINAL_DATE format: 2016-250
ISO_WEEK_DATE format: 2016-W36-2

Reference: https://docs.oracle.com/javase/10/docs/api/java/time/LocalDateTime.html#format(java.time.format.DateTimeFormatter)
Java-Functions
Java-LocalDateTime
Java-time package
Java
Java
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