Android Milliseconds since time

Question

I read all the docs and it seems not too much to really explain the date functions or the absence there.

I am trying to implement AlarmManger that needs time in milliseconds (ms) for a trigger. To check, I took the current time and added 5 seconds, and that was good.

// get a Calendar object with current time Calendar cal = Calendar.getInstance(); // add 5 minutes to the calendar object cal.add(Calendar.SECOND, 5); 

If I have a date and time, how will I get ms in that time.

Like "3/2/2011 08:15:00"

How do I turn this into milliseconds?

Answer 1

Use this method.

Example:

method call for 3/2/2011 08:15:00

 D2MS( 3, 2, 2011, 8, 15, 0); 

Method

 public long D2MS(int month, int day, int year, int hour, int minute, int seconds) { Calendar c = Calendar.getInstance(); c.set(year, month, day, hour, minute, seconds); return c.getTimeInMillis(); } 

Answer 2

When using AlarmManager, you have two choices when setting the alarm: the first is the time in seconds since the device was rebooted (do not understand this option) or, if you want an “absolute” time, then you need to provide UTC time in ms.

I think this should work - in the past I did something similar ...

 public long getUtcTimeInMillis(String datetime) { SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss"); Date date = sdf.parse(datetime); // getInstance() provides TZ info which can be used to adjust to UTC Calendar cal = Calendar.getInstance(); cal.setTime(date); // Get timezone offset then use it to adjust the return value int offset = cal.getTimeZone().getOffset(cal.getTimeInMillis()); return cal.getTimeInMillis() + offset; } 

Personally, I would recommend using a non-localized format, for example yyyy-MM-dd HH:mm:ss for any used date / time if you want to serve users around the world.

International standard ISO 8601 yyyy-MM-dd HH:mm:ss.SSSZ , but I usually did not go that far.