Java List type parameter

Question

I have a method which looks like this

public void setDayIntervals(Days day, List<HourRange> ranges) {
        int hourMask = 0;
        for (HourRange intRange : ranges) {
                     int Start= intRange.getStart();
                     int end = intRange.getEnd();
            }
        }

}

I have to pass List of Ranges from another class.

for(int s = 0; s < adSchedule.getTargets().length ; s++ ){
        List<HourRange> ranges = null;
        int Start =  adSchedule.getTargets(s).getStartHour();
        int end =  adSchedule.getTargets(s).getEndHour()-1;
            if(adSchedule.getTargets(s).getDayOfWeek()==DayOfWeek.MONDAY ){
               // ranges ????????? here i have to pass values Start and End 
               CamSchedule.setDayIntervals(Days.ONE, ranges);
             }
    }

Can someone tell me how to pass ranges in the above method setDayIntervals(Days.one, ramges)

public static class HourRange {
        int start;
        int end;

        public HourRange(int start, int end) {
            super();
            if(start > end) 
                throw new IllegalArgumentException();
            this.start = start;
            this.end = end;
        }

        public int getStart() {
            return start;
        }

        public int getEnd() {
            return end;
        }
}

What does the constructor for the HourRange class look like? — Ben Hoffstein
– Ben Hoffstein, Commented Aug 24, 2010 at 13:52
Is this homework or are you maintaining someone else's code? — BalusC
– BalusC, Commented Aug 24, 2010 at 13:57
for HourRange: you don't need to call super() because HourRange extends nothing but Object. And you could add private modifiers to start and end to make the class immutable (unless someone uses dirty tricks like reflection..) — Andreas Dolk
– Andreas Dolk, Commented Aug 24, 2010 at 14:06

Andreas Dolk · Accepted Answer · 2010-08-24 14:03:40Z

2

You have to create an HourRange object and add it to the list. Something like this:

 ranges.add(new HourRange(Start, end));

~~The example assumes that HourRange has this constructor:~~

~~public HourRange(int start, int end) { // code to copy start and end to internal fields. }~~

^{(it has this constructor)}

edited Aug 24, 2010 at 14:03

answered Aug 24, 2010 at 13:55

Andreas Dolk

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Comments

Dean J · Accepted Answer · 2010-08-24 13:57:43Z

0

Instead of

List<HourRange> ranges = null;

you probably want

List<HourRange> ranges = new ArrayList<HourRange>();

That gives you a list to add to; until you initialize ranges as a list, nothing can go into that list.

answered Aug 24, 2010 at 13:57

Dean J

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1 Comment

Mark Peters Over a year ago

Or in this case, just Collections.singletonList<HourRange>(new HourRange...

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