Question

I have to be able to store data in a new object, that I am getting from a complex object where each item is held in a List.

The hierarchy is the following:

bookId 
pageId
wordId

• bookId is unique and can have zero to many pageId's
• pageId can have zero to many wordId's

I have the data, but I need to cycle through each item and put into an object – ArrayList or similar – so I can pass off to another class, which is expecting a List. In the next class, the data is to be presented in a jsp table.

Can someone please help the best way to do this. Do I need ArrayList or ArrayLists, or is there a simple way to do it?

Answer 1

Simple way of organizing this structure is following:

class Book {
  int bookId;
  ArrayList<Page> pages;
}

class Page {
  int pageId;
  ArrayList<Word> words;
}

class Word {
  int wordId;
}

Each your entity is an object. For example Create simple book you can with next code:

Book book = new Book(); // create Book object
  ArrayList<Page> pages = new ArrayList<Page>;
  pages.add(new Page()); // add first page
  pages.add(new Page()); // add next page
book.setPages(pages); // set reference to pages for book

Note that you need provide appropriate constructors and setters/getters to operate with that code.

For presenting this data on jsp, you can use bean object Book, and with jstl you can get access to any field from book (includes each page and each word in a page) that you need.

Actually, there are lot of more complex structures but its usage depends on your requirements. I think, this model is fit for simple cases.