There might be something very simple that I'm missing here but basically I have objects that I wish to store in an arrayList that is global. However when I leave the function, and try to access the object elements in this same arrayList, a field is being overwritten and I'm not sure how.
I've nailed down the problem to a specific region and will show the relevant code. The date (timeSlot\ Calendar) object is the indicator of this problem.
requestHandler(){
Pattern pattern = Pattern.compile("*irrelevant regex*");
Matcher matcher = pattern.matcher(element);
while(matcher.find()) {
int requestID = Integer.parseInt(matcher.group(1));
Calendar startDate = dateHandler(matcher.group(2));
Calendar endDate = dateHandler(matcher.group(3));
TimeSlot timeSlot = generateTimeSlot(startDate, endDate);
TransmissionRequest t_Request = transmissionHandler(matcher.group(4));
BookingRequest request = new BookingRequest(requestID, timeSlot, t_Request);
requestList.add(request);
// debug //
System.out.println(request);
}
}
For debugging purposes I added the print statement at the very bottom, which gives me the correct output. Basically prints out timeSlot as a string for each BookingRequest. So clearly the request object with the correct timeSlot values are being added to requestList.
OUTPUT (I have left out the irrelevant fields)
BookingRequest:1
Date= 11:00 Mar-25 to 12:00 Mar-26
BookingRequest:2
Date= 12:00 Mar-24 to 03:00 Mar-27
BookingRequest:3
Date= 01:00 Mar-26 to 09:00 Mar-26
BookingRequest:4
Date= 11:00 Mar-25 to 09:00 Mar-26
BookingRequest:5
Date= 11:00 Mar-26 to 09:00 Mar-27
However, as soon as I leave this function and attempt to print this exact same output via the ArrayList requestList, I get the following.
OUTPUT
BookingRequest:1
Date= 11:00 Mar-26 to 09:00 Mar-27
BookingRequest:2
Date= 11:00 Mar-26 to 09:00 Mar-27
BookingRequest:3
Date= 11:00 Mar-26 to 09:00 Mar-27
BookingRequest:4
Date= 11:00 Mar-26 to 09:00 Mar-27
BookingRequest:5
Date= 11:00 Mar-26 to 09:00 Mar-27
It appears that each timeSlot object is being overwritten by the very last timeSlot object that is handled. I have not made any modifications to the array, and have ensured to obtain this output right after requestHandler() was called. Code below.
for(String element : input){
// Extract requests
if(element.matches("^Request.*")){
requestHandler(element);
}
}
for(BookingRequest request : requestList){
System.out.println(request);
}
Here are also the relevant handler and generate functions if you believe the problem lies in them. Both create new instances of TimeSlot and Calendar, so I don't think there is an issue with reassignment of the same instance.
public static Calendar dateHandler(String stringExtract){
Calendar date = new GregorianCalendar();
SimpleDateFormat format = new SimpleDateFormat("HH MMM dd", Locale.ENGLISH);
try {
date.setTime(format.parse(stringExtract));
} catch (ParseException e) {
e.printStackTrace();
}
return date;
}
public static TimeSlot generateTimeSlot(Calendar start, Calendar end){
TimeSlot newTimeSlot = new TimeSlot(start, end);
return newTimeSlot;
}
I have spent far too long trying to figure out what the exact problem is. I have a feeling it may also have something to do with the behaviour of matcher.find(), but I have quite literally exhausted myself trying everything to just identify what the exact problem is let alone fix it.
Any help would be more than appreciated!
