Re: Searching for a "TimeInterval" type...

From:
=?UTF-8?B?QXJuZSBWYWpow7hq?= <arne@vajhoej.dk>
Newsgroups:
comp.lang.java.programmer
Date:
Thu, 03 Oct 2013 21:41:24 -0400
Message-ID:
<524e1cc4$0$296$14726298@news.sunsite.dk>
On 10/2/2013 9:36 PM, Arne Vajh??j wrote:

On 10/2/2013 11:12 AM, Andreas Leitgeb wrote:

Arne Vajh??j <arne@vajhoej.dk> wrote:

I would be tempted to go for the simple solution with a class
that contains two ints: number of units and a Calendar
unit identifier.


Unfortunately, that would be too simple for my needs.

Some example interval of what I'm going to deal with can be
described as "tomorrow one (wall-clock)hour earlier". This just
isn't the same as in "23 hours" (nor as "82800 seconds").


Maybe two classes RelativeTime and AbsoluteTime so your
problem could be one RelativeTime with 1 HOUR and one
AbsoluteTime with HOUR X (where X is now hour minus one).


Illustration:

import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;

public class TimeManipulation {
    public static interface TimeUpdate {
        public void applyTo(Calendar cal);
    }
    public static class AbsoluteTimeUpdate implements TimeUpdate {
        private int value;
        private int field;
        public AbsoluteTimeUpdate(int value, int field) {
            this.value = value;
            this.field = field;
        }
        @Override
        public void applyTo(Calendar cal) {
            cal.set(field, value);
        }
    }
    public static class RelativeTimeUpdate implements TimeUpdate {
        private int value;
        private int field;
        public RelativeTimeUpdate(int value, int field) {
            super();
            this.value = value;
            this.field = field;
        }
        @Override
        public void applyTo(Calendar cal) {
            cal.add(field, value);
        }
    }
    private List<TimeUpdate> upds;
    public TimeManipulation(TimeUpdate... upds) {
        this.upds = new ArrayList<TimeUpdate>();
        for(TimeUpdate upd : upds) this.upds.add(upd);
    }
    public void applyTo(Calendar cal) {
        for(TimeUpdate upd : upds) {
            upd.applyTo(cal);
        }
    }
    public static void main(String[] args) {
        TimeManipulation tm = new TimeManipulation(new RelativeTimeUpdate(1,
Calendar.DAY_OF_MONTH),
                                                   new RelativeTimeUpdate(-1,
Calendar.HOUR_OF_DAY));
        Calendar cal = Calendar.getInstance();
        System.out.println(cal.getTime());
        tm.applyTo(cal);
        System.out.println(cal.getTime());
    }
}

Arne

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