How to store a tree(node with parent child relationship) in java

Hi all,
I am getting a tree with some child nodes from db. I want to store them in a proper variable like Hashmap or linkedhashmap or sortedset. But it should be able to go up to n-level in hierarchy. I am confused how to achieve that.

Please suggest some efficient ways or some similar examples.

Thanks in advance,
Vivek

Why not use a structure that's fit for a tree representation - like an actual tree structure. You can use DefaultMutableTreeNode if you don't feel like program any yourself. Although it's part of Swing, it can be used independently.