How to implement a simple scenario the OO way

Question

After starting to read a book on OO programming  I am attempting to make my android app more OO  However I am stumped on a simple scenario   I have a Book object  which can have many say Chapter objects  I also have a search function which searches across multiple books  97 of them  I end up with many Chapter objects from the Sqlite table   I felt that it would be useful to the user to be able to see the title of the book on each result  otherwise it might be confusing if there are say two  chapter 5  results   For that to happen  I need the book title  Should I make it part of my chapter object  like    chapter getBookTitle     Which kind of does not seem right  as I have glued the book name onto a chapter    The alternative is to instantiate a book object for each chapter and somehow reference it  which has its own problems including in android with regards to not being able to pass a reference to an in-memory object to another activity   Also a book may have many other chapters which were not results in the search  and it may seem like they would return if I was to just instantiate the book   What is the correct OO solution to this seemingly simple issue  Is it just a matter of learning when not to be dogmatic about the whole OO thing   More Info   I am using FTS4 in Sqlite  which accounts for over half of my actual DB size of 80mb  What I am storing is text from 97 books  with chapters in 4 languages  So my FTS at the moment stores   ChapterId  ChapterNo  withinBook   Lang1  Lang2  Lang3  Lang4  Tags  Notes   The searching is very fast  I retrieve only 50 results  I match any column with a string term  and not one column in particular  So if I type  apple  it will search all the fields above   Currently as part of my FTS query I am join a join onto Book  fetching the BookId  I later use that to get me the title of the book  However its all in a procedural like style  with no regard to where the information  belongs    I need the title so I can display it in the results  just for user convenience   It works well  however I am wanting similar performance or slightly less but with an OO approach as I think that will make more sense to me when I come back to this project after a long pause

User · Answer

You might implement your class model by composition  having the book object have a map of chapter objects contained within it  map chapter number to chapter object   Your search function could be given a list of books into which to search by asking each book to search its chapters  The book object would then iterate over each chapter  invoking the chapter search   function to look for the desired key and return some kind of index into the chapter  The book s search   would then return some data type which could combine a reference to the book and some way to reference the data that it found for the search  The reference to the book could be used to get the name of the book object that is associated with the collection of chapter search hits

User · Answer

The Chapter object should have reference to the book it came from so I would suggest something like  chapter getBook   getTitle     Your database table structure should have a books table and a chapters table with columns like   books   id book specific info  etc   chapters   id book id chapter specific info etc   Then to reduce the number of queries use a join table in your search query

User · Answer

The approach I would take is  when reading the chapters from the database  instead of a collection of chapters  use a collection of books  This will have your chapters organised into books and you ll be able to use information from both classes to present the information to the user  you can even present it in a hierarchical way easily when using this approach

[java] How to implement a simple scenario the OO way

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