Java: Data Science Made Easy

Writing the map method

First, we will create the TextMapper class, which will implement the map method. This class inherits from the Mapper class and has two private instance variables, pages and bookTitle. pages is an IntWritable object and bookTitle is a Text object. IntWritable and Text are used because these objects will need to be serialized to a byte stream before they can be transmitted to the servers for processing. These objects take up less space and transfer faster than the comparable int or String objects:

public static class TextMapper         extends Mapper<Object, Text, Text, IntWritable> {     private final IntWritable pages = new IntWritable();     private final Text bookTitle = new Text(); } 

Within our TextMapper class we create the ...