Android - checking if time is between certain hours of the day

Question

in my app I'm updating some stuff if the time is between certain hours of the day which the user choose. It works fine if the user chooses something like "07-21", but not with "21-07" which is over the night. How I'm doing to check the time is I'm getting the current hour and converting it into milliseconds. Then I check if the current milli is between the chosen hours (those are also converted into milliseconds). Like this:

    if (currentMilli >= startHourMilli && currentMilli <= endHourMilli) 

The problem: It doesn't work if the user chooses anything that is over midnight (19-08 for example).

I've tried a lot of stuff but I just can't figure out how to do this.

Any help is appreciated!

Beerbohm

Can you please post the code where you set startHourMilli and endHourMilli? – Freewheeling

When you say over midnight, do you mean over midday? All times except midnight are over midnight! – Sandisandidge

Answer 1

Do you increase the day of the year by 1 when you're passing midnight? Otherwise your startHourMilli might be greater than endHourMilli and your if-clause will always be false.

The solution is to use the add-method of the Calendar class. Therefore I calculate the interval's length in hours and add this value to our Calendar instance.

int start = 21; // let's take your failing example: 21-07
int end = 7;
int hours = (end - start) % 24; // here hours will be 14

Calendar cal = Calendar.getInstance();
// set calendar to TODAY 21:00:00.000
cal.set(Calendar.HOUR_OF_DAY, start);
cal.set(Calendar.MINUTE, 0);
cal.set(Calendar.SECOND, 0);
cal.set(Calendar.MILLISECOND, 0);

long startHourMilli = cal.getTimeInMillis();

// add 14 hours = TOMORROW 07:00:00.000
cal.add(Calendar.HOUR_OF_DAY, hours); 
long endHourMilli = cal.getTimeInMillis();

Let me know if this helps :)

Freewheeling

Answer 2

Simplest way to check..

val isDayTime : Boolean
    get() {
        val cal = Calendar.getInstance()
        val hour = cal.get(Calendar.HOUR_OF_DAY)
        return hour in 8..20
    }

Frontality

Answer 3

Date has the functions before and after for comparing two dates. Hope this documentation helps you:

http://developer.android.com/reference/java/util/Date.html#after(java.util.Date)

http://developer.android.com/reference/java/util/Date.html#before(java.util.Date)

Best regards.

Ranice

Answer 4

I'm answering my own question because I think I came up with something that might work for what I'm trying to do:

if(endHourMilli < startHourMilli){
if(currentMilli >= startHourMilli && currentMilli <= 23*3600000 || currentMilli >= 0 && currentMilli <= endHourMilli){
//Do whatever 
}
}else{
if (currentMilli >= startHourMilli && currentMilli <= endHourMilli) {
//Do whatever
}
}

It should work even if endMilli is less than startMilli, or have I screwed something up here?

Beerbohm

Answer 5

I know I'm a little late to the party, but recently I developed android app that needed to work within given timeframe, and since I didn't like working with Calendar I ended up using something like this:

// if start hour is later than end hour
// example: start = 21, end = 07
int startHourMilli = 21, endHourMilli = 07;
// just add one day (in your case in millis)
if (startHourMilli > endHourMilli) endHourMilli += 24 * 60 * 60 * 1000;
// now here you can check without any problems
if(currentMilli >= startHourMilli && currentMilli < endHourMilli){
    // within timeframe, do stuff you need
} else {
    // not in timeframe, find solution
}

Now I know that you found yourself a solution, but I think that my approach may be a little more understandable (at least to newbies that might get confused).

Nicaea

Answer 6

You can always use simple if / else for 24 hour format, without using functions or additional calculations:

For Example1: Full time period from StartHour to StopHour(stop hour include all minutes)

int StartHour = 23; //start from 23:00

int StopHour = 9; // until current hour is 9 that will include until 9:59

int CurrentHour = 2;

if (StartHour > StopHour)
{
  if (CurrentHour < StartHour && StopHour < CurrentHour) 
  {Inside = false;}
  else
  {Inside = true;}
}
else
{
  if (CurrentHour >= StartHour && StopHour >= CurrentHour) 
  {Inside = true;}
   else
  {Inside = false;}
}

At the end if Inside == true CurrentHour is in time range StartHour - StopHour(full stop hour)

And do something else if both equal:
if (StartHour == StopHour) {..............};

For Example2: If you want to stop at this exact StopHour hour, you need some changes:

int StartHour = 23; //start from 23:00

int StopHour = 9; // this will stop after 8:59

int CurrentHour = 2;

if (StartHour2 > StopHour2)
{
  if (Hr24 < StartHour2 && StopHour2 <= Hr24) 
  {Quiet = false;}
  else
  {Quiet = true;}
}
else
{
  if (Hr24 >= StartHour2 && StopHour2 > Hr24) 
  {Quiet = true;}
   else
  {Quiet = false;}
}

At the end if Inside == true CurrentHour is in time range StartHour - StopHour(exact)

Redmer

Answer 7

I think that ottel142 is almost ok but it shoud be:

 public static boolean checkIfNight() {
    int start = 21;
    int end = 7;
    int hours = 24 - start + end; 

    Calendar cal = Calendar.getInstance();
    cal.set(Calendar.HOUR_OF_DAY, start);
    cal.set(Calendar.MINUTE, 0);
    cal.set(Calendar.SECOND, 0);
    cal.set(Calendar.MILLISECOND, 0);

    long startHourMilli = cal.getTimeInMillis();
    KLog.e(cal.getTime());

    cal.add(Calendar.HOUR_OF_DAY, hours);
    long endHourMilli = cal.getTimeInMillis();

    long currentMilli = Calendar.getInstance().getTimeInMillis();


    if (currentMilli >= startHourMilli && currentMilli <= endHourMilli)
        return true;
    else return false;

}

Anglicanism