Java8 Comparator: 列表排序的深入讲解

List<String> cities = Arrays.asList(
  "Milan",
  "london",
  "San Francisco",
  "Tokyo",
  "New Delhi"
);
System.out.println(cities);
//[Milan, london, San Francisco, Tokyo, New Delhi]
cities.sort(String.CASE_INSENSITIVE_ORDER);
System.out.println(cities);
//[london, Milan, New Delhi, San Francisco, Tokyo]
cities.sort(Comparator.naturalOrder());
System.out.println(cities);
//[Milan, New Delhi, San Francisco, Tokyo, london]

List<Integer> numbers = Arrays.asList(6, 2, 1, 4, 9);
System.out.println(numbers); //[6, 2, 1, 4, 9]
numbers.sort(Comparator.naturalOrder());
System.out.println(numbers); //[1, 2, 4, 6, 9]

List<Movie> movies = Arrays.asList(
    new Movie("Lord of the rings"),
    new Movie("Back to the future"),
    new Movie("Carlito's way"),
    new Movie("Pulp fiction"));
movies.sort(Comparator.comparing(Movie::getTitle));
movies.forEach(System.out::println);

return (Comparator<T> & Serializable)
    (c1, c2) -> keyExtractor.apply(c1).compareTo(keyExtractor.apply(c2));

List<Movie> movies = Arrays.asList(
    new Movie("Lord of the rings", 8.8),
    new Movie("Back to the future", 8.5),
    new Movie("Carlito's way", 7.9),
    new Movie("Pulp fiction", 8.9));
movies.sort(Comparator.comparingDouble(Movie::getRating)
           .reversed());
movies.forEach(System.out::println);

List<Movie> movies = Arrays.asList(
    new Movie("Lord of the rings", 8.8, true),
    new Movie("Back to the future", 8.5, false),
    new Movie("Carlito's way", 7.9, true),
    new Movie("Pulp fiction", 8.9, false));
movies.sort(new Comparator<Movie>() {
  @Override
  public int compare(Movie m1, Movie m2) {
    if(m1.getStarred() == m2.getStarred()){
      return 0;
    }
    return m1.getStarred() ? -1 : 1;
   }
});
movies.forEach(System.out::println);

movies.sort((m1, m2) -> {
  if(m1.getStarred() == m2.getStarred()){
    return 0;
  }
  return m1.getStarred() ? -1 : 1;
});

movies.sort(Comparator.comparing(Movie::getStarred, (star1, star2) -> {
  if(star1 == star2){
     return 0;
  }
  return star1 ? -1 : 1;
}));

List<Movie> movies = Arrays.asList(
    new Movie("Lord of the rings", 8.8, true),
    new Movie("Back to the future", 8.5, false),
    new Movie("Carlito's way", 7.9, true),
    new Movie("Pulp fiction", 8.9, false));
movies.sort(Comparator.comparing(Movie::getStarred)
           .reversed()
           .thenComparing(Comparator.comparing(Movie::getRating)
           .reversed())
);
movies.forEach(System.out::println);