Learning RxJava - Second Edition

Making a function a lambda

Lambda expressions can also implement the Function interface, which has a single abstract method that accepts arguments and returns an item. For instance, RxJava 2.0 (as well as Java 8) has a Function<T, R> interface that accepts a T type and returns an R type. This means that you can declare a Function<String, Integer>, whose apply() method accepts a String and returns an Integer. For example, we can implement apply() by returning the string's length in an anonymous class, as shown here:

import java.util.function.Function;public class A_12 {    public static void main(String[] args) {        Function<String,Integer> lengthMapper =                new Function<String, Integer>() {                    @Override                    public Integer apply(String s) {                        return s.length() ...