Java Date and Time

Java Date and Time

Java date and time is the function that deals with the programming related to the date and time constants. Java does not possess a built-in Date class but if the programmer needs to use that that they can import the java.time package in order to work with the date and time API.

This package in Java consists of many date and time classes. For instance:

Display Current Date

In order to display the current date the programmer have to import the java.time.LocalDate class and then use its now() method that is as depicted in the example below:

import java.time.LocalDate; //First import LocalDate class
public class CurrDate 
{
  public static void main(String[] args) 
  {
    LocalDate CurrDate = LocalDate.now(); 
    System.out.println(CurrDate); // Print  the current date
  }
}

Display Current Time

In order to display the current time (hour, minute, second, and milliseconds) the programmer have to import the java.time.LocalTime class, and use its now() method that is as depicted in the example below:

import java.time.LocalTime; //First need to  import LocalTime class
public class CurrTime{
  public static void main(String[] args) 
  {
    LocalTime CurTime = LocalTime.now();
    System.out.println(CurTime);
  }
}

Display Current Date and Time

In order to display the current date and time the programmer have to import the java.time.LocalDateTime class, and use its now() method that is as depicted in the example below:

import java.time.LocalDateTime; //First need to  import LocalDateTime class
public class CurrDateTime 
{
  public static void main(String[] args) {
    LocalDateTime CurDateTime = LocalDateTime.now();
    System.out.println(CurDateTime);
  }
}

Formatting Date and Time

The programmers can use the DateTimeFormatter class along with the ofPattern() method in the exact same package in order to format or parse the date-time objects. The example that is depicted below will remove both the "T" and milliseconds from the date-time, please have a thorough look at this example:

//First we have to Import the LocalDateTime class
import java.time.LocalDateTime; 

//After importing of local Date Time Class Import DateTimeFormatter class
import java.time.format.DateTimeFormatter; 

public class Main{
  public static void main(String[] args) 
  {
    LocalDateTime myDateTimeObj = LocalDateTime.now();
    System.out.println("Display Date time Before formatting: " + myDateTimeObj);
    DateTimeFormatter myDateTimeFormatObj = DateTimeFormatter.ofPattern("dd-MM-yyyy HH:mm:ss");

    String formattedDateTime = myDateTimeObj.format(myDateTimeFormatObj);
    System.out.println("Display Date time After formatting: " + formattedDateTime);
  }
}

If the programmers wish to display the date and time in a varying format then the ofPattern() method is used that is known for accepting all sort of values. Here is an example that will depict everything regarding this method:

In order to specify the time format a time pattern string is used and in this pattern all the letters that are mentioned are all ASCII letters and are reserved as pattern letters. Here is a table that is depicting how they are defined: