How can I compare hours?

Question

I am building an app, and I need to know how to compare two hours.

For example, my store opens at 6:30 AM and closes at 5:00 PM.

I need to show in a TextView that after 5 PM my store is closed, and after 6:30 AM my store is open, from Monday to Friday.

How can I do this? This is my attempt:

public void timer() {
    Calendar c = Calendar.getInstance();
    int timeOfDay = c.get(Calendar.HOUR_OF_DAY);
    int open = 6:30; // 1 ERROR HERE WITH ":"
    int close = 17;

    if (timeOfDay < close) {
        hour.setText.("OPEN");
    }
}

But I am getting multiple errors. One in int open when I put 06:30 with ":"; two with limit of Monday to Friday.

Thanks for the help.

Answer 1

You should be using the Java 8 Date & Time library, because Calendar and Date are obsolete.

The LocalTime class should be sufficient.

LocalTime open = LocalTime.of(6, 30);
LocalTime closed = LocalTime.of(17, 0);

LocalTime currentTime = LocalTime.now();
if (currentTime.isBefore(open) || currentTime.isAfter(closed)) {
    // Closed
}

You could then use the DateTimeFormatter class to format the time into the desired format.

If you want to also take the day of the week into consideration while determining the opening times of your shop, then you could use LocalDateTime in conjunction with abovementioned example:

LocalDateTime now = LocalDateTime.now();

// The opening days. Static import these from java.time.DayOfWeek
Set<DayOfWeek> daysOpen = new HashSet<>(Arrays.asList(
    MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY));
// Opening and closing times
LocalTime timeOpen = LocalTime.of(6, 30);
LocalTime timeClosed = LocalTime.of(17, 0);

if (!daysOpen.contains(now.getDayOfWeek()) || now.toLocalTime().isBefore(timeOpen) || now.toLocalTime().isAfter(timeClosed)) {
    System.out.println("Closed");
}
else {
    System.out.println("Open");
}

Answer 2

The constant HOUR_OF_DAY is an integer representing only the hour. I would suggest to use the method getTime() (see this link) and then work with the returned Date object.

Answer 3

I couldn't think of a very concise way to do this, but perhaps you can use this method

public boolean isOpen(Calendar c) {
   int minute = c.get(Calendar.MINUTE);
   int hour = c.get(Calendar.HOUR_OF_DAY);
   return (hour < 17 && (hour > 6 || (hour == 6 && minute >=30)));
}

This should return true if it is between 6:30 and 17:00 and false at any other time

(If the hour is less than 17, and (the hour is greater than 6, or the hour is 6 and the minutes are 30 or higher))

Answer 4

The HOUR_OF_DAY field works like this.

10:04:15 PM the HOUR_OF_DAY is 22.

You can't get 6:30 am because it only tells you what hour it is not minute.

You can get minutes by calling MINUTE.

A few changes would be:

public void timer () {
    Calendar c = Calendar.getInstance();
    int timeOfDay = c.get(Calendar.HOUR_OF_DAY);
    int minuteOfHour = c.get(Calendar.MINUTE); -> same as Hour
    int open = 6; -> you shouldn't use ':' with an int
    int openMinutes = 30;
    int close = 17;

    if(timeOfDay >= open && minuteOfHour >= openMinutes && timeOfDay < close){
        hour.setText.("OPEN");
    }}

Answer 5

Use following code:

        Calendar openingHour = Calendar.getInstance();
        openingHour.set(Calendar.HOUR_OF_DAY, 6);
        openingHour.set(Calendar.MINUTE, 30);
        openingHour.set(Calendar.SECOND, 0);
        openingHour.set(Calendar.MILLISECOND, 0);

        Calendar closingHour = Calendar.getInstance();
        closingHour.set(Calendar.HOUR_OF_DAY, 17);
        closingHour.set(Calendar.MINUTE, 0);
        closingHour.set(Calendar.SECOND, 0);
        closingHour.set(Calendar.MILLISECOND, 0);

        Calendar currentTime = Calendar.getInstance();
        int dayOfWeek = currentTime.get(Calendar.DAY_OF_WEEK);
        if( dayOfWeek % 7 > 1  && currentTime.before(closingHour) && currentTime.after(openingHour)){
           System.out.println("Store is open");
        } else {
           System.out.println("Store is closed");
        }