OperationsWithOptional.java

package com.github.java8.lambdasinaction.chap10;

import java.util.*;

import static java.util.Optional.of;
import static java.util.Optional.empty;

public class OperationsWithOptional {

    public static void main(String... args) {
        System.out.println(max(of(3), of(5)));
        System.out.println(max(empty(), of(5)));
    }

    public static final Optional<Integer> max(Optional<Integer> i, Optional<Integer> j) {
         return i.flatMap(a -> j.map(b -> Math.max(a, b)));
    }
}