Thread: Calendar Issue

Ok, I have a problem where: given two dates and a frequency, a list of dates are returned in that range based on that frequency.

The dates are formatted mm/dd/yyyy where leading zeros are not included.
The frequency is formatted in one of 3 ways:
1) Daily - Occurs every day of week
2) X... - Occurs every day of week except the dates after the X
3) ... - Occurs only on the days indicated
The days in the frequency are determined by a number, ranging 1 to 7 where 1 is Monday and 7 is Sunday. So, the frequency X6 would say: "Every day except Saturday" and the frequency 126 would say: "Only on Monday, Tuesday, and Saturday".

Now, to accomplish this task, I have a method that returns a List<Date>. Inside that method, I have a boolean array of 7 where each index is a day of the week (where Monday is index 0). I then set the booleans true/false based on the frequencies. After that, I compute each day in the range and check its Day Of Week to see if it is in the frequency. If it is, I add it to my List<Date>, if not, I exclude it. Here is my code for that method:

    public List<Date> getDates(String star,String end,String frequency)
    {
    	//Where frequencies[0] == Monday
    	boolean[] frequencies = new boolean[7];
 
    	if(frequency.equalsIgnoreCase("Daily"))
    	{
    		for(int i=0;i<frequencies.length;i++)
    		{
    			frequencies[i]=true;
    		}
    	}
    	else if(frequency.contains("X") || frequency.contains("x"))
    	{
    		for(int i=0;i<frequencies.length;i++)
    		{
    			frequencies[i] = true;
    		}
    		String n = frequency.substring(1);
    		for(int i=0;i<n.length();i++)
    		{
    			int v = Integer.parseInt(n.substring(i,i+1));
    			frequencies[v-1] = false;
    		}
    	}
    	else
    	{
    		for(int i=0;i<frequency.length();i++)
    		{
    			int v = Integer.parseInt(frequency.substring(i,i+1));
    			frequencies[v-1] = true;
    		}
    	}
 
 
    	String[] eSplit = star.split("/");
    	String[] dSplit = end.split("/");
    	Date d1 = new Date(Integer.parseInt(eSplit[2]),Integer.parseInt(eSplit[0])-1,Integer.parseInt(eSplit[1]));
    	Date d2 = new Date(Integer.parseInt(dSplit[2]),Integer.parseInt(dSplit[0])-1,Integer.parseInt(dSplit[1]));
    	List<Date> dates = new ArrayList<Date>();
		long interval = 1000 * 60 * 60 * 24;
		long endTime = d2.getTime();
		long curTime = d1.getTime();
		while (curTime <= endTime)
		{
			Date temp = new Date(curTime);
			Calendar check = new GregorianCalendar(temp.getYear(), temp.getMonth(), temp.getDate());
			check.setFirstDayOfWeek(Calendar.MONDAY);
			int dayOfWeek = check.get(Calendar.DAY_OF_WEEK);
			if(frequencies[dayOfWeek-1])
		  		dates.add(new Date(curTime));
		  	curTime += interval;
		}
		return dates;
    }

The problem I am having is that the dates it returns are incorrect. Specifically, it would seem it is 1 day early and for some it doesn't even find dates. For example, for in restriction of:
1/4/2011 to 2/16/2011 for 6:
it returns:
1/7/2011
1/14/2011
1/21/2011
1/28/2011
2/4/2011
2/11/2011
while it should return:
1/8/2011
1/15/2011
1/22/2011
1/29/2011
2/5/2011
2/12/2011

Another example is that for the restriction of:
12/21/2010 to 1/3/2011 for 6:
it returns:
12/24/2010
12/31/2010
while it should return:
12/25/2010
1/1/2011


Any clues as to what is happening? I need to figure this out fairly quickly.

I figured it out. Apparently Calendar.setFirstDayOfWeek(Calendar.MONDAY); doesnt exactly set the first day of week to be Monday. It is more complicated than that. Either way, I figured it out.