The sound of our own data
Being notified about data changes can be rather useful as we can make an application-level decision regarding whether the change is important or not and react accordingly. The first interface that we are going to look at is
EntryListener. This class will notify us when changes are made to the entries stored in a map collection. If we take a look at the interface, we can see four entry event types and two map-wide events that we will be notified about.
EntryListener has also being broken up into a number of individual super
MapListener interfaces. So, should we be interested in only a subset of event types, we can implement the appropriate super interfaces as required. Let's take a look at the following code:
void entryAdded(EntryEvent<K, ...