Java: Data Science Made Easy

Understanding Java 8 lambda expressions and streams

A lambda expression can be expressed in several different forms. The following illustrates a simple lambda expression where the symbol, ->, is the lambda operator. This will take some value, e, and return the value multiplied by two. There is nothing special about the name e. Any valid Java variable name can be used:

e -> 2 * e 

It can also be expressed in other forms, such as the following:

(int e) -> 2 * e (double e) -> 2 * e (int e) -> {return 2 * e; 

The form used depends on the intended value of e. Lambda expressions are frequently used as arguments to a method, as we will see shortly.

A stream can be created using a number of techniques. In the following example, a stream is created ...