Java collection keeping only n last inserted members

Question

As the title states, I am looking for a java collection keeping only the N last objects inserted into the collection. This FIFO collection does not need to implement random access or support changing N.

All collections I can find are either blocking (LinkedBlockingQueue) or of unlimited size (ArrayDeque). I found org.eclipse.jetty.util.ArrayQueue but as you could guess this brings quite an unwanted dependency on my project and also is very complicated since it support changing N so its not what I need.

Do you know if there is a way to have that with a quite common java library or do I have to write it myself?

Answer 1

Check out Apache Commons CircularFifoBuffer

CircularFifoBuffer is a first in first out buffer with a fixed size that replaces its oldest element if full.

The removal order of a CircularFifoBuffer is based on the insertion order; elements are removed in the same order in which they were added. The iteration order is the same as the removal order.