Lambda termination operation Max & min

max&min

​ Can be used to or the maximum value in the stream .

Example ：

​ Get the highest and lowest scores of the books produced by these writers respectively and print .

//         Get the highest and lowest scores of the books produced by these writers respectively and print .
        //Stream<Author>  -> Stream<Book> ->Stream<Integer>  -> evaluation 

        List<Author> authors = getAuthors();
        Optional<Integer> max = authors.stream()
                .flatMap(author -> author.getBooks().stream())
                .map(book -> book.getScore())
                .max((score1, score2) -> score1 - score2);

        Optional<Integer> min = authors.stream()
                .flatMap(author -> author.getBooks().stream())
                .map(book -> book.getScore())
                .min((score1, score2) -> score1 - score2);
        System.out.println(max.get());
        System.out.println(min.get());