Working with Date and Time in Java

1.Get current time in Java

This below function returns current system time

        /**
	 * Function to return the current time
	 * @return The current time
	 * @see #getCurrentFormattedTime(String)
	 */

	public static Date getCurrentTime() {
		Calendar calendar = Calendar.getInstance();
		return calendar.getTime();
	}

2. Get Current time in given format

The below Function to return the current time, formatted as per the DateFormatString setting

         /**
	 * Function to return the current time, formatted as per the      `DateFormatString setting
	 * @param dateFormatString The date format string to be applied
	 * @return The current time, formatted as per the date format string             specified
	 * @see #getCurrentTime()
	 * @see #getFormattedTime(Date, String)
	 */

	public static String getCurrentFormattedTime(String dateFormatString) {
		DateFormat dateFormat = new SimpleDateFormat(dateFormatString);
		Calendar calendar = Calendar.getInstance();
		return dateFormat.format(calendar.getTime());
	}

3. Convert the given time into particular format and returns the same

The below function takes Time and Format as input as returns the time after changing to given format

         /**
	 * Function to format the given time variable as specified by the DateFormatString setting
	 * @param time The date/time variable to be formatted
	 * @param dateFormatString The date format string to be applied
	 * @return The specified date/time, formatted as per the date format string specified
	 * @see #getCurrentFormattedTime(String)
	 */

	public static String getFormattedTime(Date time, String dateFormatString) {
		DateFormat dateFormat = new SimpleDateFormat(dateFormatString);
		return dateFormat.format(time);
	}

4.Returns the difference between two time

         /**
	 * Function to get the time difference between 2 {@link Date} variables in minutes/seconds format
	 * @param startTime The start time
	 * @param endTime The end time
	 * @return The time difference in terms of hours, minutes and seconds
	 */

	public static String getTimeDifference(Date startTime, Date endTime) {
		long timeDifferenceSeconds = (endTime.getTime() - startTime.getTime()) / 1000;	// to convert from milliseconds to seconds
		long timeDifferenceMinutes = timeDifferenceSeconds / 60;
		
		String timeDifferenceDetailed;
		if (timeDifferenceMinutes >= 60) {
			long timeDifferenceHours = timeDifferenceMinutes / 60;
			
			timeDifferenceDetailed = Long.toString(timeDifferenceHours) + " hour(s), "
									+ Long.toString(timeDifferenceMinutes % 60) + " minute(s), "
									+ Long.toString(timeDifferenceSeconds % 60) + " second(s)";
		} else {
			timeDifferenceDetailed = Long.toString(timeDifferenceMinutes) + " minute(s), "
									+ Long.toString(timeDifferenceSeconds % 60) + " second(s)";
		}
		
		return timeDifferenceDetailed;
	}