Streams, Collectors, and Optionals for Data Processing in Java 8

The Stream API and the Collectors are two new additions to the JDK in Java 8 that allow the efficient processing of data using the map / filter / reduce approach. It brings many new patterns on the table, and ways to extend them. We show how to connect streams to non-standard sources of data, how to build streams on other streams. The notion of Optional, introduced to handle the reduction of empty streams is also shown on advanced data processing patterns. And at last, collectors are shown, basic patterns first then advanced ones, where we build our own custom collector.