Java并行流中嵌套循环导致结果不一致的问题：原因与解决方案

import java.util.ArrayList;
import java.util.List;

// 示例：Person, Address, PersonAddressPair 类定义
class Person {
    private Integer id;
    private String name;
    public Person(Integer id, String name) { this.id = id; this.name = name; }
    public Integer getId() { return id; }
    public String getName() { return name; }
}

class Address {
    private Integer personId;
    private String city;
    public Address(Integer personId, String city) { this.personId = personId; this.city = city; }
    public Integer getPersonId() { return personId; }
    public String getCity() { return city; }
}

class PersonAddressPair {
    Person person;
    Address address;
    public PersonAddressPair(Person person, Address address) { this.person = person; this.address = address; }
    // ... toString(), equals(), hashCode()
}

public class DataProcessor {

    // 模拟数据获取
    private List<Person> getPersonDetails() {
        List<Person> persons = new ArrayList<>();
        for (int i = 0; i < 1000; i++) persons.add(new Person(i, "Person " + i));
        return persons;
    }

    private List<Address> getAddressDetails() {
        List<Address> addresses = new ArrayList<>();
        for (int i = 0; i < 1000; i++) {
            if (i % 2 == 0) addresses.add(new Address(i, "City " + i));
        }
        return addresses;
    }

    public List<PersonAddressPair> processDataIncorrectly() {
        List<Person> personList = getPersonDetails();
        List<Address> addressList = getAddressDetails();

        // !! 这是一个非线程安全的List，在并行环境下写入会导致数据丢失或不一致 !!
        List<PersonAddressPair> resultSet = new ArrayList<>();

        personList.parallelStream().forEach(person -> {
            // 嵌套循环，根据personId匹配地址并生成组合
            for (Address address : addressList) {
                if (address.getPersonId().equals(person.getId())) {
                    // 多个线程可能同时尝试修改 resultSet，导致数据竞争
                    // 例如：一个线程正在添加元素，另一个线程同时读取或修改其内部结构，
                    // 结果可能丢失部分添加操作，或导致内部状态损坏。
                    resultSet.add(new PersonAddressPair(person, address));
                }
            }
        });
        return resultSet;
    }
}

import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

// ... Person, Address, PersonAddressPair 类定义
// ... getPersonDetails(), getAddressDetails() 方法

public class DataProcessor {
    // ... (其他方法) ...

    public List<PersonAddressPair> processDataWithConcurrentCollection() {
        List<Person> personList = getPersonDetails();
        List<Address> addressList = getAddressDetails();

        // 使用CopyOnWriteArrayList，它在写入时会创建内部数组的副本，确保线程安全
        List<PersonAddressPair> resultSet = new CopyOnWriteArrayList<>();

        personList.parallelStream().forEach(person -> {
            for (Address address : addressList) {
                if (address.