Java Stream.map用法详解与实例

List<String> words = Arrays.asList("hello", "world");

List<String> upperWords = words.stream()

    .map(String::toUpperCase)

    .collect(Collectors.toList());

class User {

  private String name;

  public User(String name) { this.name = name; }

  public String getName() { return name; }

}

List<User> users = Arrays.asList(new User("Alice"), new User("Bob"));

List<String> names = users.stream()

    .map(User::getName)

    .collect(Collectors.toList());

List<Integer> numbers = Arrays.asList(1, 2, 3, 4);

List<Integer> squares = numbers.stream()

    .map(n -> n * n)

    .collect(Collectors.toList());