Do you need an algorithm for determining that a new element has been added to the collection?

Question

Java

The task is the following, there is a collection private Map dataFromRisCarton = new LinkedHashMap<>();
Data is written to it (with http post). How to find out that a new element has been added to the collection and display it?
Probably there is a ready algorithm.
Thanks in advance!

Answer 1

Make a successor from LinkedHashMap. Override the add method and add all new elements in it to the adjacent list. Also add a method that displays new elements and at the same time clears the list of new elements.