java.util.Calendar and java.util.Date

java.util.Date – Is a point in time (maintains millisecond accuracy)

java.util.Calendar –helps manipulate and compare java.util.Date

 

To convert Date to Calendar

 

        Calendar cal1 = Calendar.getInstance();

        Date currentTime = new Date(); // run on May, 28^th 2009

        cal1.setTime(currentTime);

        assertEquals(2009, cal1.get(Calendar.YEAR)); // returns true

        assertEquals(Calendar.MAY, cal1.get(Calendar.MONTH)); // returns true

        assertEquals(28, cal1.get(Calendar.DATE)); // returns true

 

To convert Calendar to Date

 

        Date date2 = cal1.getTime();

 

To find dates relative to each other – example to find the date tomorrow and yesterday

 

        Calendar cal1 = Calendar.getInstance();

        Date currentTime = new Date();// run on May, 28^th 2009

        cal1.setTime(currentTime);

        cal1.roll(Calendar.DATE, 1); // one day after the date represented by cal1 i.e. 29th

        assertEquals(2009, cal1.get(Calendar.YEAR)); // returns true

        assertEquals(Calendar.MAY, cal1.get(Calendar.MONTH)); // returns true

        assertEquals(29, cal1.get(Calendar.DATE)); // returns true

 

        cal1.roll(Calendar.DATE, -1); // one day before the date represented by cal1 i.e. 28th

        assertEquals(2009, cal1.get(Calendar.YEAR)); // returns true

        assertEquals(Calendar.MAY, cal1.get(Calendar.MONTH)); // returns true

        assertEquals(28, cal1.get(Calendar.DATE)); // returns true