How to format Java LocalDateTime as ISO_DATE_TIME format

At first, set the date:

LocalDateTime dateTime = LocalDateTime.of(2019, Month.JULY, 9, 10, 20);

Now, format the datetime as ISO_DATE_TIME format:

String str = dateTime.format(DateTimeFormatter.ISO_DATE_TIME);

Example

import java.time.LocalDateTime;
import java.time.Month;
import java.time.format.DateTimeFormatter;
public class Demo {
   public static void main(String[] args) {
      LocalDateTime dateTime = LocalDateTime.of(2019, Month.JULY, 9, 10, 20);
      System.out.println("DateTime = "+dateTime);
      String str = dateTime.format(DateTimeFormatter.ISO_DATE_TIME);
      System.out.println("Formatted date = "+str);
   }
}

Output

DateTime = 2019-07-09T10:20
Formatted date = 2019-07-09T10:20:00