Java: Convert long time of day to timestamp

Question

I have a long value that represents the time of day in milliseconds since midnight that day. i.e. 00:00:01 would be 1000.

I want to convert this to a long timestamp since the epoch - using the current System's day, month, year. What's the best way to do this?

Which day? Which data type are you interested in? It's really not clear what you're asking. Also, bear in mind time zones - do you have a "time of day" in a UTC day, or in some specific time zone? — Jon Skeet, Jan 22 '13 at 09:50
The current system day and date, sorry should have specified — James, Jan 22 '13 at 09:52

score 1 · Accepted Answer · edited May 23 '17 at 12:12

    final Calendar instance = Calendar.getInstance();
    instance.set(Calendar.HOUR, 0);
    instance.set(Calendar.MINUTE, 0);
    instance.set(Calendar.SECOND, 0);
    instance.set(Calendar.MILLISECOND, 0);
    long result = instance.getTimeInMillis() + yourTime;

Also note that Calendar#getInstance does the following:

Calendar cal = createCalendar(TimeZone.getDefaultRef(), Locale.getDefault());

The resulting time will change according to the default set TimeZone (and yes it can change !). See this post: java Timezone setDefault effects

score 0 · Answer 2 · answered Jan 22 '13 at 10:17

0

Try this:

Date date = new Date(your_long_value);

answered Jan 22 '13 at 10:17

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Java: Convert long time of day to timestamp

2 Answers2