how to choose or write my own java data structure allowing multi attributes search

Question

I have a pretty large list containing many instances of one class, this class has many attributes(member variables). My problem is to find a feasible data structure to store these instances that allow searches based on multiple attributes like database search(ie A Student class, each student has age, date of birth, grade and GPA.find all 2nd year students whose ages are between 20 and 23). The Map seems not applicable as it only allow single key and if I create multi attribute index for searching, the big O is still not decreased. I also considered using trees like AVL tree, and I don't think it would work.

I'd be grateful if someone could give me some hints.

Answer 1

I think what you are looking for is an Inverted Index (using attribute name + value as keys) or possibly one Inverted Index per attribute. A search would build the intersection of all results found for each attribute.

Answer 2

You could do this:

• Build an AVL tree with objects sorted by the most recurrent attribute (just one, eg "id" or "name").
• Then create a search function that instead of taking a value, takes a Java lambda expression F (so your seacrh condition must be something like F(myObj) == true instead of myObj.deFaultAttribute == searchParameter )
• For the example you gave, F could be something like ((myObj) -> myObj.year==2 && myObj.age>=20 && myObj.age<=23)

I hope it helps.