Multi-stream: paginate a joined result with skip and limit

skip and limit paginate, but only over a deterministic order - sort before you page or the same page number returns different rows on the next run. The sort must come first, the skip second.

Code

record Author(int id, String name) {}
record Book(String title, int authorId) {}

var authors = List.of(new Author(1, "Ava"), new Author(2, "Ben"));
var books = List.of(new Book("Streams", 1), new Book("Kafka", 2), new Book("SQL", 1),
                    new Book("JVM", 2), new Book("HTTP", 1));

Map<Integer, String> nameOf = authors.stream().collect(Collectors.toMap(Author::id, Author::name));
int page = 1, size = 2;   // zero-based

var rows = books.stream()
        .map(b -> nameOf.get(b.authorId()) + " - " + b.title())
        .sorted()
        .skip((long) page * size)
        .limit(size)
        .toList();

System.out.println("page " + page + " (size " + size + "): " + rows);

Output

page 1 (size 2): [Ava - Streams, Ben - JVM]