Calculating time for Android alarm

In Android we set an alarm by setting the time until it goes off in milliseconds. I开发者_如何转开发s there an easy way to find how many milliseconds there are until a certain time (hh:mm) or do I just have to calculate it mathematically?

Thanks!

Save your current time in milliseconds as

Calandar calendar = Calendar.getInstance();
Long currenttime =  calendar.getTimeInMillis();
Long settime= <your set time in milliseconds>;

Here you can calculate the difference as follows:

Long differencetime = settime -  currenttime;
int dif=(int)differencetime/1000;

Here you can set the time in calendar:

calendar.set(Calendar.SECOND, calendar.get(Calendar.SECOND) + dif);

Here you can set the alarm for the settime.

AlarmManager alarmManager1 = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
alarmManager1.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pi1);

Check out the first argument for AlarmManager.set(): With RTC/RTC_WAKEUP, you can specify a fixed time rather than an elapsed time.

That said, if you need to use the elapsed time, it's pretty trivial to calculate the number of milliseconds that need to elapse. Worst case, you could use the Calendar and/or Date classes.

Date now = new Date(), b = new Date(year, month, day, hour, min);

b.getTime() - a.getTime();

And here's another way to get the time in milliseconds to a certain time:

Calendar c = Calendar.getInstance();
c.set(c.YEAR, c.MONTH, c.DAY_OF_MONTH, 17, 1, 0); // 5:01 pm
long alarmTime = c.getTimeInMillis();

AlarmManager am = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
Intent intent = new Intent(context, AlarmNotification.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intent, 0);
am.setRepeating(AlarmManager.RTC_WAKEUP, alarmTime, 1000 * 60 * 60 * 24, pendingIntent); // Millisec * Second * Minute * Hour // Same time every day

• RTC_WAKEUP allows the alarm to still activate when the phone is asleep. Use RTC if you want to wait until the user wakes up the phone themself.
• Use am.set() if you don't want the alarm to repeat

Let me know if this helps.