Circular Dynamic Queue

Question

I was wondering how to make a dynamic queue circular. I thought that maybe I should keep track of how many Nodes there are (by adding 1 to an int variable tracker initially at zero each time a Node is added) and then when it reaches the limit (chosen by user) it would add no more Nodes. Then, I though that to make it circular, then I should check for when the tracker has reached that limit, and instead of making the next Node variable in the last Node null, it should be simply the first Node. I know that what I have written is extremely confusing, but if you understand the concept of Nodes, queues, and what the heck I'm talking about, then at least explain what a circular queue should look like. Thanks.

Answer 1

I was wondering how to make a dynamic queue circular.Why make it circular if it's dynamic? What you probably want is a FIFO (first-in-first-out) queue. One common implementations is to use a linked list. You add nodes at the end and remove them from the front. LinkedList even have methods for that.
The other common implementation is a circular buffer. You use a static array with a fixed length. You keep two indexes. One is pointing at the first free position. It's where you add a node and increment the index. The other is pointing at the last element. It's where you remove a node and increment the index. When an index becomes larger than the array size it "wraps" to zero. That's why it's called circular.
I've posted an implementation here,
http://forum.java.sun.com/thread.jspa?forumID=256&threadID=477885