DateHelp.java

/**
 * This is a quick tutorial on how to learn dates for CS631. I am not trying to aid in your project but provide some more
 * insight on how I like to use the Java Date Object.
 * 
 * NOTE: I just realized that it seems like he wants us to use DateFormatter & Gregorian Calendar, so don't use SimpleDateFormat but the 
 * concepts behind it should be similar. 
 * 
 */
public void learnDates() throws Exception{ 

		/**
		 * Dates are stored as longs. The long number represents the number of milliseconds since JAN01-1970. Dates should always be worked 
		 * with as Dates and not their String representations because it is easier to compare/modify and they require less memory. 
		 */
		
		// Create a date object with the current date and time.
		Date dateRightNow = new Date(System.currentTimeMillis());
		
		/**
		 * Since dates are stored as longs (under the hood), you can get a lot of information out of them in any way you want. To learn more of the 
		 * formatting, look up the SimpleDateFormat parsing inputs.
		 */
		final String DATE_FORMAT = "yyyy-mm-dd HH:mm:ss"; 
		
		// Create the date formatter so we can parse the date
		SimpleDateFormat dateFormatter = new SimpleDateFormat(DATE_FORMAT);

		// Now we want a fancy representation of the Date object we just created
		String nowAsString = dateFormatter.format(dateRightNow);
		System.out.println(nowAsString); // prints 2014-02-12 09:48:00 if it was right now
		
		// Now say we want to take a string representation of a date we already have and turn it into a String. 
		Date dateInThePast = dateFormatter.parse("2014-02-06 12:12:13");
		// now we have a date object that we can store in our class.
		
		// Now if you wanted to compare dates, use their long values
		if( dateInThePast.getTime() < dateRightNow.getTime() )
		{
			// do something.
		}
	}