使用java8流组合规范列表

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

class Person {
    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }
}

public class StreamExample {
    public static void main(String[] args) {
        List<Person> people = Arrays.asList(
            new Person("Alice", 25),
            new Person("Bob", 17),
            new Person("Charlie", 30)
        );

        List<String> adultsInUpperCase = people.stream()
            .filter(person -> person.getAge() > 18) // 过滤出成年人
            .map(person -> person.getName().toUpperCase()) // 名字转大写
            .collect(Collectors.toList()); // 收集结果到列表

        System.out.println(adultsInUpperCase); // 输出: [ALICE, CHARLIE]
    }
}

List<String> safeNames = people.stream()
    .filter(person -> person != null) // 排除null元素
    .map(Person::getName)
    .filter(Objects::nonNull) // 确保名字不为null
    .collect(Collectors.toList());