java - 使用带参数的构造函数填充对象列表

Question

我需要填充类(class)学生列表:

class Student {
    String firstName;
    String lastName;
    public Student(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }

这是生成器方法签名:

public List<Student> generateRandomStudents(int quantity) {
List<Student> students;
// List is populated by required quantity of students
return students;

我尝试过的:

List<Student> students = Stream
    .of(new Student(getRandomStringFromFile("firstnames.txt"), getRandomStringFromFile("lastnames.txt")))
    .limit(quantity)
    .collect(Collectors.toList());

仅创建 1 名学生。 2)尝试使用 Stream.generate，但它仅适用于供应商，并且我无法将我的参数用于构造函数。

Answer 1

Stream.of(new Student(..))生成仅包含该单个元素的流。

您想要的是 Supplier<Student>它可以产生随机 Student ，然后使用Stream.generate(Supplier<?>)生成源源不断的随机学生流(稍后limit):

Supplier<Student> randomStudent = () -> new Student(
        getRandomStringFromFile("firstnames.txt"), 
        getRandomStringFromFile("lastnames.txt"));

List<Student> students = Stream.generate(randomStudent)
        .limit(quantity)
        .collect(Collectors.toList());

或内联:

List<Student> students = Stream
        .generate(() -> new Student(
                getRandomStringFromFile("firstnames.txt"),
                getRandomStringFromFile("lastnames.txt")))
        .limit(quantity)
        .collect(Collectors.toList());