Time consts in Java?

Question

Is there a Java package with all the annoying time constants like milliseconds/seconds/minutes in a minute/hour/day/year? I\'d hate to duplicate something like that.

Answer 1

I would go with java TimeUnit if you are not including joda-time in your project already. You don't need to include an external lib and it is fairly straightforward.

Whenever you need those "annoying constants" you usually need them to mutliply some number for cross-unit conversion. Instead you can use TimeUnit to simply convert the values without explicit multiplication.

This:

long millis = hours * MINUTES_IN_HOUR * SECONDS_IN_MINUTE * MILLIS_IN_SECOND;

becomes this:

long millis = TimeUnit.HOURS.toMillis(hours);

If you expose a method that accepts some value in, say, millis and then need to convert it, it is better to follow what java concurrency API does:

public void yourFancyMethod(long somePeriod, TimeUnit unit) {
    int iNeedSeconds = unit.toSeconds(somePeriod);
}

If you really need the constants very badly you can still get i.e. seconds in an hour by calling:

int secondsInHour = TimeUnit.HOURS.toSeconds(1);