Search code examples
javaobjectarraylisthashmapmultimap

Multimap of Multimap Java - Categorize timetable

I have parsed a HTML timetable and loaded every Subject to my class object. So i have arrayList of my Subjects which has information of name, teacher,... ,HOUR, and DAY now i want to reconstruct the table and so I need to categorize it first. I think that best would be to have structure like this:

Monday: 1: Math, Czech, ...
        2: History
        ...
Tuesday: 1: English, Geo
         2...
...

There can be mutiple subjects in given hour, therefore I tried to used Multimap of Multimap, but I am not able to declare it during my for parsing.

Multimap<String, Multimap<String, Subject>> timetable = HashMultimap.create();
...
for ...
    timetable.put(subject.den, new HashMultimap<>(subject.hod, subject));

but it says that HashMultimap has private accesin com.google.common... I dont know how to correctly write this. I was also thinking about using Array, but I would have to pre-declare it and I would like to build this during one for cycle. Any ideas? Thank you in advance

Solution

  • It looks like what you want is actually more of a Map<String, Multimap<String, Subject>>, in which case you want

     Map<String, Multimap<String, Subject>> timetable = new HashMap<>();
 for ...
   Multimap<String, Subject> multimap = timetable.get(subject.den);
   if (multimap == null) {
     multimap = HashMultimap.create();
     timetable.put(subject.den, multimap);
   }
   multimap.put(subject.hod, subject);