Java Date and Time

Java Dates

Java does not have a built-in Date class, but we can import the java.time package to work with the date and time API. The package includes many date and time classes. For example:

Display Current Date

To display the current date, import the java.time.LocalDate class, and use its now() method:

import java.time.LocalDate; // import the LocalDate class

public class Main {
  public static void main(String[] args) {
    LocalDate myObj = LocalDate.now(); // Create a date object
    System.out.println(myObj); // Display the current date
  }
}

Display Current Time

To display the current time (hour, minute, second, and nanoseconds), import the java.time.LocalTime class, and use its now() method:

import java.time.LocalTime; // import the LocalTime class

public class Main {
  public static void main(String[] args) {
    LocalTime myObj = LocalTime.now();
    System.out.println(myObj);
  }
}

Display Current Date and Time

To display the current date and time, import the java.time.LocalDateTime class, and use its now() method:

import java.time.LocalDateTime; // import the LocalDateTime class

public class Main {
  public static void main(String[] args) {
    LocalDateTime myObj = LocalDateTime.now();
    System.out.println(myObj);
  }
}

Formatting Date and Time

The "T" in the example above is used to separate the date from the time. You can use the DateTimeFormatter class with the ofPattern() method in the same package to format or parse date-time objects. The following example will remove both the "T" and nanoseconds from the date-time:

import java.time.LocalDateTime; // Import the LocalDateTime class
import java.time.format.DateTimeFormatter; // Import the DateTimeFormatter class

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

    String formattedDate = myDateObj.format(myFormatObj);
    System.out.println("After formatting: " + formattedDate);
  }
}

这 ofPattern() method accepts all sorts of values, if you want to display the date and time in a different format. For example: