Being notified as our data changes can be rather useful, so we can make an application-level decision on whether that change is important or not. The first interface 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 event types that we will be notified about.
public interface EntryListener<K, V> extends EventListener { void entryAdded(EntryEvent<K, V> event); void entryRemoved(EntryEvent<K, V> event); void entryUpdated(EntryEvent<K, V> event); void entryEvicted(EntryEvent<K, V> event); }
Hopefully, the first three are pretty self-explanatory; however, the last is a little less clear and in fact, one of the most useful. The entryEvicted
method is invoked when an entry is removed from a map non-programmatically (that is, Hazelcast has done it all by itself). This instance will occur in one of two...