We are planning to use cache but we dont have any cache mechanism in the cache actually there should be some thing which provide the key, value and entry iteration that are consistent with an order of entry. For this we came up with two approaches indexing that list and LisnkedHashMap. But dont know what are disadvantages and overheads with LinkedhashMap. Please give me some useful information and suggestions on this.
If you need ordered key-value entries, then I think LHM it is simply the most natural choice for you (as far as Java is concerned). There may be some collection implementations that provide better performance, but frankly, I doubt it would be more than a marginal difference. One thing that might be significant in your case is that LHM is not synchronized. However, you may always use Collections#synchronizedMap() to enforce it. I looked in java.util.concurrent package, but haven't found ordered concurrent map implementation.
I'm afraid there is no such class in the Java API (at least I never heard of it ). There is java.util.Hashtable and java.util.concurrent.ConcurrentHashMap (which are quite similar, with the latter being a bit faster for some operations), but as far as I know, neither of them supports element ordering, which is one of Sreedhar's requirements.