As most Java developers know, putting values in a Java Map (like a HashMap) involves creating a large number of auxiliary objects under the covers. For example, a HashMap with int keys and long values might, for each entry, create a wrapped Integer, a wrapped Long object, and a Node that holds the former values together with a hash value and a link to other potential Node objects sharing the same hash bucket. Perhaps even more tantalizing is that a wrapped Integer might be created each time the Map is queried! For example, using the Map::get operation.
In this short tutorial, we will devise a way of creating an object-creation-free, light-weighted mapper with rudimentary lookup capability that is suitable for a limited number of associations. The mapper is first created and initialized, whereafter it can be queried. Interestingly, these mappers can also be serialized/deserialized and sent over the wire using Chronicle’s open-source libraries without incurring additional object creation.