如何检查事件是否少于30分钟？

Question

I am creating an events. I want to check if the event is less than 30 minutes. I don't want to allow user to add the event if it is less than 30 minutes.

I am storing the time in date format.

Date format is

 df = new SimpleDateFormat("E MMM dd hh:mm:ss zzzz yyyy");

I have two dates datefrom and dateto . I tried to get the minutes of datefrom and dateto and minus the from minutes from to minutes and if total minutes are less than 30 then the user can't add the event.

But it's not working well. Every time the event can't be added.

My attempt was :

   long frmMins = datefrom.getMinutes();

            long toMins = dateto.getMinutes();

            long calMinutes = toMins - frmMins;


 else if (calMinutes < 30) {
                        showAlert("Event can not be less than 30 Minutes.");
                    }

Log of event:

Date: Sat Mar 19 16:00:00 GMT+05:30 2016,Todate: Sat Mar 19 23:59:00 GMT+05:30 2016

To convert in millis and then in minutes my attempt was this:

       long frmMillis = datefrom.getTime();

            long frmMins = TimeUnit.MILLISECONDS.toMinutes(frmMillis);

            long toMillis = dateto.getTime();
            long toMins = TimeUnit.MILLISECONDS.toMinutes(toMillis);

            long calMinutes = toMins - frmMins;

But it gives minus values most of the times.

How can I do this?

Answer 1

You can try with this also -

long diff = dateto.getTime() - datefrom.getTime();
long diffSeconds = diff / 1000 % 60;
long diffMinutes = diff / (60 * 1000) % 60;
if (diffMinutes < 30) {
    showAlert("Event can not be less than 30 Minutes.");
   }

Answer 2

Since we are doing it in android i would suggest you use alarm manager to achieve this

alarmMgr.setInexactRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP,
        AlarmManager.INTERVAL_HALF_HOUR,
        AlarmManager.INTERVAL_HALF_HOUR, alarmIntent);

This sends an alarm for every half an hour. Now you need a reciver to handle the event rest is upto your app logic here is a complete working example http://www.vogella.com/tutorials/AndroidServices/article.html