Using local-variable syntax for lambda parameters

In this recipe, you will learn how to use the local-variable syntax (discussed in the previous recipe) for lambda parameters and the motivation for introducing this feature. It was introduced in Java 11.

Getting ready

Until the release of Java 11, there were two ways to declare parameter types—explicit and implicit. Here is an explicit version:

BiFunction<Double, Integer, Double> f = (Double x, Integer y) -> x / y;
System.out.println(f.apply(3., 2));    //prints: 1.5

And the following is an implicit parameter type definition:

BiFunction<Double, Integer, Double> f = (x, y) -> x / y;
System.out.println(f.apply(3., 2));     //prints: 1.5

In the preceding...