Java Date formats

Working with java.util.Date and java.util.Calendar.

Java Date Examples

Few examples to work with Date APIs.

1. Convert Date to String.

   	SimpleDateFormat sdf = new SimpleDateFormat("dd/M/yyyy");
   	String date = sdf.format(new Date()); 
   	System.out.println(date); //15/10/2013

2. Convert String to Date.

   	SimpleDateFormat sdf = new SimpleDateFormat("dd-M-yyyy hh:mm:ss");
   	String dateInString = "31-08-1982 10:20:56";
   	Date date = sdf.parse(dateInString);
   	System.out.println(date); //Tue Aug 31 10:20:56 SGT 1982

3. Get current date time

   	SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
   	Date date = new Date();
   	System.out.println(dateFormat.format(date)); //2013/10/15 16:16:39

4. Convert Calendar to Date

   	Calendar calendar = Calendar.getInstance();
           Date date =  calendar.getTime();

Java Calendar Examples

Few examples to work with Calendar APIs.

1. Get current date time

   	SimpleDateFormat sdf = new SimpleDateFormat("yyyy MMM dd HH:mm:ss");	
   	Calendar calendar = new GregorianCalendar(2013,0,31);
   	System.out.println(sdf.format(calendar.getTime()));
    
   
   Output
   
   2013 Jan 31 00:00:00
   

2. Simple Calendar example

   	SimpleDateFormat sdf = new SimpleDateFormat("yyyy MMM dd HH:mm:ss");	
   	Calendar calendar = new GregorianCalendar(2013,1,28,13,24,56);
   
   	int year       = calendar.get(Calendar.YEAR);
   	int month      = calendar.get(Calendar.MONTH); // Jan = 0, dec = 11
   	int dayOfMonth = calendar.get(Calendar.DAY_OF_MONTH); 
   	int dayOfWeek  = calendar.get(Calendar.DAY_OF_WEEK);
   	int weekOfYear = calendar.get(Calendar.WEEK_OF_YEAR);
   	int weekOfMonth= calendar.get(Calendar.WEEK_OF_MONTH);
   
   	int hour       = calendar.get(Calendar.HOUR);        // 12 hour clock
   	int hourOfDay  = calendar.get(Calendar.HOUR_OF_DAY); // 24 hour clock
   	int minute     = calendar.get(Calendar.MINUTE);
   	int second     = calendar.get(Calendar.SECOND);
   	int millisecond= calendar.get(Calendar.MILLISECOND);
   		
   	System.out.println(sdf.format(calendar.getTime()));
   		
   	System.out.println("year 		: " + year);
   	System.out.println("month 		: " + month);
   	System.out.println("dayOfMonth 	: " + dayOfMonth);
   	System.out.println("dayOfWeek 	: " + dayOfWeek);
   	System.out.println("weekOfYear 	: " + weekOfYear);
   	System.out.println("weekOfMonth 	: " + weekOfMonth);
   		
   	System.out.println("hour 		: " + hour);
   	System.out.println("hourOfDay 	: " + hourOfDay);
   	System.out.println("minute 		: " + minute);
   	System.out.println("second 		: " + second);
   	System.out.println("millisecond 	: " + millisecond);
    
   
   Output
   
   2013 Feb 28 13:24:56
   year 		: 2013
   month 		: 1
   dayOfMonth 	: 28
   dayOfWeek 	: 5
   weekOfYear 	: 9
   weekOfMonth     : 5
   hour 		: 1
   hourOfDay 	: 13
   minute 		: 24
   second 		: 56
   millisecond     : 0
   
   

3. Set a date manually.

   	SimpleDateFormat sdf = new SimpleDateFormat("yyyy MMM dd HH:mm:ss");	
   		
   	Calendar calendar = new GregorianCalendar(2013,1,28,13,24,56);	
   	System.out.println("#1. " + sdf.format(calendar.getTime()));
   
   	//update a date
   	calendar.set(Calendar.YEAR, 2014);
   	calendar.set(Calendar.MONTH, 11);
   	calendar.set(Calendar.MINUTE, 33);
   		
   	System.out.println("#2. " + sdf.format(calendar.getTime()));
    
   
   Output
   
   #1. 2013 Feb 28 13:24:56
   #2. 2014 Dec 28 13:33:56
   

4. Add or subtract from a date.

   	SimpleDateFormat sdf = new SimpleDateFormat("yyyy MMM dd");	
   		
   	Calendar calendar = new GregorianCalendar(2013,10,28);	
   	System.out.println("Date : " + sdf.format(calendar.getTime()));
   
   	//add one month
   	calendar.add(Calendar.MONTH, 1);
   	System.out.println("Date : " + sdf.format(calendar.getTime()));
   		
   	//subtract 10 days
   	calendar.add(Calendar.DAY_OF_MONTH, -10);
   	System.out.println("Date : " + sdf.format(calendar.getTime()));
    
   
   Output
   
   Date : 2013 Nov 28
   Date : 2013 Dec 28
   Date : 2013 Dec 18
   

5. Convert Date to Calendar.

           SimpleDateFormat sdf = new SimpleDateFormat("dd-M-yyyy hh:mm:ss");
   	String dateInString = "22-01-2015 10:20:56";
   	Date date = sdf.parse(dateInString);
   
           Calendar calendar = Calendar.getInstance();
   	calendar.setTime(date);