RxJava通过匹配属性值来连接可观察流

Question

可以说我有两个可观察的流

Observable<Book> books;
Observable<Movie> movies;

如果它们具有匹配的属性,我如何加入这些？像下面的psudo代码:

Observable<BookMoviePair> pairs = books.join(movies)
    .where((book, movie) -> book.getId() == movie.getId()))
    .return((book, movie) -> new BookMoviePair(book, movie));

Answer 1

一种方法是：

Observable<BookMoviePair> pairs =
        books.flatMap(book -> movies
                .first(movie -> movie.getId() == book.getId())
                .map(movie -> new BookMoviePair(book, movie)));