Aging Objects in a Collection

Question

I want to be able to age objects in a Collection.

For example I could put strings in a HashSet.

1. I would like timestamps associated of when the String was put in the HashSet.
2. I would like String older than say time X to be dropped from the HashSet.
3. I would like to be able to say "touch" a string and update the time to when it was inserted in the Collection.

So I can accomplish this by keeping track of each String and then running a house cleaning Thread and purging String from the Collection if it is older than a certain time quantum.

However I am looking for:

1. Either a Clever way to do this.
2. An existing open-source java component which accomplishes this.

Thanks.

Answer 1

Sounds like you need a cache. Either try CacheBuilder (see Caches Explained) from Guava or EhCache.

Answer 2

Google Guava caches meet all your requirements and more! See Caches Explained.

Answer 3

I would use JCS, really like the Guava idea though @sjr

Answer 4

Why not just create your own Collection class (for the house cleaning tasks) that's backed by a HashMap<String, Date> ?