如何通过从java流中过滤出子对象来检索父对象

Question

Person 是我的根 POJA，我有电话号码列表作为我的子对象。

String firstName;

String lastName;

Long id;

List<String> phoneNumber = new ArrayList<>();

int age;


public Person(String firstName, String lastName, int age, Long id, List<String> phone) {
    super();
    this.firstName = firstName;
    this.lastName = lastName;
    this.age = age;
    this.id = id;
    this.phoneNumber = phone;
}

List<Person> personList = Arrays.asList(
    new Person("Abdul", "Razak", 27, 50L, Arrays.asList("100", "101", "102")),
    new Person("Udemy", "tut", 56, 60L, Arrays.asList("200", "201", "202")),
    new Person("Coursera", "tut", 78, 20L, Arrays.asList("300", "301", "302")),
    new Person("linked", "tut", 14, 10L, Arrays.asList("400", "401", "402")),
    new Person("facebook", "tut", 24, 5L, Arrays.asList("500", "501", "502")),
    new Person("covila", "tut", 34, 22L, Arrays.asList("600", "602", "604")),
    new Person("twitter", "tut", 64, 32L, Arrays.asList("700", "702", "704"))
);

List<String> list = personList.stream()
    .map(p -> p.getPhoneNumber().stream())
    .flatMap(inputStream -> inputStream)
    .filter(p -> p.contains("502"))
    .collect(Collectors.toList());

我想检索号码等于特定字符串的人。是否可以通过使用流来实现这一点？

List<String> list = personList.stream()
    .map(p -> p.getPhoneNumber().stream())
    .flatMap(inputStream -> inputStream)
    .filter(p -> p.contains("502"))
    .collect(Collectors.toList());

简单来说，如何通过过滤子对象来检索父对象？

Answer 1

personList.stream().filter((person)->person.getContacts().contains("100"))
                .collect(Collectors.toList());

会给你匹配的Person。