What is the best way to increase Java.sql.date/time?

Question

I have a problem when I have a MySQL database storing dates and times in separate columns. However, in Java code, I need to increase the received timestamp for the date and time from the database by minutes, hours or days, and then update the corresponding columns in the database.

I am currently using Java.sql.date and java.sql.time types in Java. Can anyone suggest a better method for this?

I can achieve the above:

public static String addToDateTime(String timestampIn, String increment) { // Decompose timestamp. int year = Integer.parseInt(timestampIn.substring(0, 4)); int month = Integer.parseInt(timestampIn.substring(5, 7)); int day = Integer.parseInt(timestampIn.substring(8, 10)); int hours = Integer.parseInt(timestampIn.substring(11, 13)); int mins = Integer.parseInt(timestampIn.substring(14, 16)); int secs = Integer.parseInt(timestampIn.substring(17, 19)); Calendar calendar = new GregorianCalendar(year, month - 1, day, hours, mins, secs); // Increment timestamp. if (increment.equals("HOURLY")) { calendar.add(Calendar.HOUR, 1); } else if (increment.equals("DAILY")) { calendar.add(Calendar.HOUR, 24); } else if (increment.equals("WEEKLY")) { calendar.add(Calendar.HOUR, 168); } else if (increment.equals("DO NOT POLL")) { // Do nothing. } // Compose new timestamp. SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); String timestampOut = sdf.format(calendar.getTime()); return timestampOut; } 

But I would prefer something less primitive.

thanks

Mr. Morgan

Answer 1

You can use Joda's time. Then you can use DateTime plusHours , plusDays and plusWeeks . For parsing, there are DateTimeFormat and DateTimeFormatter . Sort of:

 DateTimeFormatter fmt = DateTimeFormat.forPattern("YYYY-MM-dd HH:mm:ss"); DateTime dt = fmt.parseDateTime(timestampin); if (increment.equals("HOURLY")) { dt = dt.plusHours(1); } else if (increment.equals("DAILY")) { dt = dt.plusDays(1); } else if (increment.equals("WEEKLY")) { dt = dt.plusWeeks(1); } String timestampOut = fmt.print(dt); 

Perhaps you can use something like:

 DateTime dt = new DateMidnight(sqlDate).plus(Period.millis(sqlTime.getTime())); 

This assumes sql.Time represents the number of milliseconds since midnight.

Answer 2

Here's an optimization, assuming the input is java.util.Date , in which you can just pass java.sql.Date and java.sql.Time , since they are its subclasses.

 public static String addToDateTime(Date date, Increment increment) throws ParseException { Calendar calendar = calendar.getInstance(); calendar.clear(); calendar.setTime(date); switch (increment) { case HOURLY: calendar.add(Calendar.HOUR, 1); break; case DAILY: calendar.add(Calendar.DATE, 1); break; case WEEKLY: calendar.add(Calendar.WEEK_OF_YEAR, 1); break; case DO_NOT_POLL: break; } return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(calendar.getTime()); } public enum Increment { HOURLY, DAILY, WEEKLY, DO_NOT_POLL; } 

which can be used as

 String newTimestamp = addToDateTime(timestampIn, Increment.WEEKLY); 

To learn more about the useful enum , check out Sun's tutorial on this . However, according to Java 7, you must be able to switch to String .

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However, I strongly agree with the JodaTime recommendation, here is an example:

 public static String addToDateTime(Date date, Increment increment) { DateTime dt = new DateTime(date); switch (increment) { case HOURLY: dt = dt.plusHours(1); break; case DAILY: dt = dt.plusDays(1); break; case WEEKLY: dt = dt.plusWeeks(1); break; case DO_NOT_POLL: break; } return df.print(dt); } public enum Increment { HOURLY, DAILY, WEEKLY, DO_NOT_POLL; } 

The difference is admittedly not shocking, but it also has more advantages.