Date&Time In Java

Java provides the Date class available in java.util package, this class encapsulates the current date and time.

The Date class supports two constructors as shown in the following table.

Following are the methods of the date class.

Getting Current Date and Time

This is a very easy method to get current date and time in Java. You can use a simple Date object with toString() method to print the current date and time as follows −

Example

import java.util.Date;
public class DateDemo {

   public static void main(String args[]) {
      // Instantiate a Date object
      Date date = new Date();

      // display time and date using toString()
      System.out.println(date.toString());
   }
}

This will produce the following result −

Output

on May 04 09:51:52 CDT 2009

Date Comparison

Following are the three ways to compare two dates -

You can use getTime( ) to obtain the number of milliseconds that have elapsed since midnight, January 1, 1970, for both objects and then compare these two values.

You can use the methods before( ), after( ), and equals( ). Because the 12th of the month comes before the 18th, for example, new Date(99, 2, 12).before(new Date (99, 2, 18)) returns true.

You can use the compareTo( ) method, which is defined by the Comparable interface and implemented by Date.

Date Formatting Using SimpleDateFormat

SimpleDateFormat is a concrete class for formatting and parsing dates in a locale-sensitive manner. SimpleDateFormat allows you to start by choosing any user-defined patterns for date-time formatting.

Example

import java.util.*;
import java.text.*;

public class DateDemo {

   public static void main(String args[]) {
      Date dNow = new Date( );
      SimpleDateFormat ft = 
      new SimpleDateFormat ("E yyyy.MM.dd 'at' hh:mm:ss a zzz");

      System.out.println("Current Date: " + ft.format(dNow));
   }
}

This will produce the following result −

Output

Current Date: Sun 2004.07.18 at 04:14:09 PM PDT

Simple DateFormat Format Codes

To specify the time format, use a time pattern string. In this pattern, all ASCII letters are reserved as pattern letters, which are defined as the following −

Date Formatting Using printf

Date and time formatting can be done very easily using printf method. You use a two-letter format, starting with t and ending in one of the letters of the table as shown in the following code.

Example

import java.util.Date;
public class DateDemo {

   public static void main(String args[]) {
      // Instantiate a Date object
      Date date = new Date();

      // display time and date
      String str = String.format("Current Date/Time : %tc", date );

      System.out.printf(str);
   }
}

This will produce the following result −

Output

Current Date/Time : Sat Dec 15 16:37:57 MST 2012

It would be a bit silly if you had to supply the date multiple times to format each part. For that reason, a format string can indicate the index of the argument to be formatted.

The index must immediately follow the % and it must be terminated by a $.

Example

import java.util.Date;
public class DateDemo {

   public static void main(String args[]) {
      // Instantiate a Date object
      Date date = new Date();
  
      // display time and date
      System.out.printf("%1$s %2$tB %2$td, %2$tY", "Due date:", date);
   }
}

This will produce the following result −

Output

Due date: February 09, 2004

Alternatively, you can use the < flag. It indicates that the same argument as in the preceding format specification should be used again.

Example

import java.util.Date;
public class DateDemo {

   public static void main(String args[]) {
      // Instantiate a Date object
      Date date = new Date();
  
      // display formatted date
      System.out.printf("%s %tB %< te, %< tY", "Due date:", date);
   }
}

This will produce the following result −

Output

Due date: February 09, 2004