How to get number of milliseconds from start of day [closed]

Question

For example, if it's 1 p.m (13:00) and I need to get the number 46800000 (13 hours from beginning o day) in milliseconds. Could anyone please help?

Answer 1

You can use a Calendar to calculate it. You set the time to the hour 0 and calculate the difference:

Calendar c = Calendar.getInstance();
c.set(Calendar.HOUR_OF_DAY, 0);
c.set(Calendar.MINUTE, 0);
c.set(Calendar.SECOND, 0);
c.set(Calendar.MILLISECOND, 0);
long millis = (System.currentTimeMillis() - c.getTimeInMillis());