Java: Data Science Made Easy

Using Java 8 to perform map-reduce

In the next section, we will use Java 8 streams to perform a map-reduce operation similar to the one demonstrated using Hadoop in the Using map-reduce section. In this example, we will use a Stream of Book objects. We will then demonstrate how to use the Java 8 reduce and average methods to get our total page count and average page count.

Rather than begin with a text file, as we did in the Hadoop example, we have created a Book class with title, author, and page-count fields. In the main method of the driver class, we have created new instances of Book and added them to an ArrayList called books. We have also created a double value average to hold our average, and initialized our variable totalPg to zero: ...