Java: from Lucene Hits to original objects

Question

I'd like to implement a filter/search feature in my application using Lucene.

Querying Lucene index gives me a Hits instance, which is nothing more than a list of Documents matching my criteria.

Since I generate the indexed Documents from my objects, which is the best way to find the original object related to a specific Lucene Document?

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A better description of my situation:
- Three model classes for now: Folder (can have other Folders or Lists as children), List (can have Tasks as children) and Task (can have other Tasks as children). They are all DefaultMutableTreeNode subclasses. I'll add the Tag entity in the future.
- Each Task has a text, a start date, a due date, some boolean flags.
- They are displayed in a JTree.
- The hole tree is saved in an XML file.
- I'd like to do things like these:
* search Tasks with Google-like queries.
* Find all Tasks that start today.
* Filter Tasks by Tag.

Answer 1

You can't, not with vanilla Lucene. You said yourself that you converted your objects into Documents and then stored the Documents in Lucene, how would you imagine that process would be reversible?

If you want to store and retrieve your own objects in Lucene, I strongly recommend that you use Compass instead. Compass is to Lucene what Hibernate is to JDBC - you define a mapping between your objects and Lucene documents, Compass takes care of the conversion.

Answer 2

Add a "stored" field that contains an object identifier. For each hit, lookup the original object via the identifier.

Without knowing more context, it's hard to be more specific.