如何在 Java 中使用流/lambda 重复调用 0 参数函数并将返回值收集到列表中？

Question

Say I would like to create a "random" list of 100 users by using the fakeRandomUser function below.

public class User {
    String name;

    static public User fakeRandomUser() {
        User user = new User();
        user.name = "foobar";
        return user;
    }

}

Is it possible to do this with the Stream API instead of appending to a list in a loop?

Answer 1

One way is to construct an IntStream of 100 items, and map it to your fakeRandomUser function:

List<User> users = IntStream.range(0, 100)
    .mapToObj(e -> User.fakeRandomUser())
    .collect(Collectors.toList());

Another way is to use Stream.generate() , like so:

List<User> users = Stream.generate(User::fakeRandomUser)
    .limit(100)
    .collect(Collectors.toList())